CN105758928B - A kind of sugar Structural Identification method and sugared Structural Identification device - Google Patents

A kind of sugar Structural Identification method and sugared Structural Identification device Download PDF

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Publication number
CN105758928B
CN105758928B CN201610109049.XA CN201610109049A CN105758928B CN 105758928 B CN105758928 B CN 105758928B CN 201610109049 A CN201610109049 A CN 201610109049A CN 105758928 B CN105758928 B CN 105758928B
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structure
candidate
sugar
corresponding
step
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CN201610109049.XA
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CN105758928A (en
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孙世伟
卜东波
杨飞
王耀军
李岩
黄纯翠
陈润生
高枫
刘亚名
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中国科学院计算技术研究所
中国科学院生物物理研究所
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Abstract

The invention discloses a kind of sugared Structural Identification method and sugared Structural Identification devices, the sugar Structural Identification method includes: step 1: the corresponding minor structure of sugared structure spectral peak to be measured, which carried out, using multi-stage ms information predicts, candidate minor structure of the minor structure as corresponding spectral peak;And step 2: utilizing De Novo sugar Structural Identification technology, assembles complete sugared structure according to the corresponding candidate minor structure of mass spectrum spectral peak.The present invention is based on sugared structure multi-stage ms data, using De Novo sugar Structural Identification technology, realize the identification of sugared structure, realize multi-stage ms De Novo sugar Structural Identification algorithm, by effectively utilizing multi-stage ms information, it not only significantly improves De Novo and enumerates the efficiency of sugared structure fragment in the process, but also be obviously reduced sugared candidate structure set.

Description

A kind of sugar Structural Identification method and sugared Structural Identification device

Technical field

The present invention relates to biological information field more particularly to a kind of sugared Structural Identification method and sugared Structural Identification devices.

Background technique

Saccharide compound is the large biological molecule that critical function is played in vital movement, is present in carefully with various structures configuration In born of the same parents, irreplaceable work is played in life processes such as cell cycle regulating, apoptosis aging, the interactions of cell surface With.

Tree-like branched structure is presented by being formed by multiple monosaccharide by glucosides key connection in saccharide compound, therefore, sugar Identification of the identification of class compound mainly comprising information such as carbohydrate ingredient, the monosaccharide order of connection and branch sites.Fig. 1 a And Fig. 1 b is the representation of glycosidic bond in the corresponding ring structure of monosaccharide and sugared structure.Fig. 2 a to Fig. 2 d indicates N-linked A variety of representations of sugared GlcNAc2Man9 structure, wherein root node is located at the right end of structure, i.e. N-terminal, child node to the left by Step extends, and forms C-terminal, wherein one monosaccharide of each node on behalf, each edge represents the glycosidic bond of two monosaccharide connection.Due to one A monosaccharide can connect to form branched structure by glycosidic bond with other one or more monosaccharide, result in saccharide compound knot The diversity of structure configuration.

First mass spectrometric and second order ms data are mostly based on currently based on mass spectrographic saccharide compound identification strategy.Level-one Mass spectrum can only obtain the quality of sugar compounds parent ion, and the company being unable to get between the monosaccharide composition of sugar compounds structure, monosaccharide Connect site and structural information.Second order ms are further to smash sugar in a mass spectrometer to carry out minor structure information analysis, at present Mainly include following several strategies:

1) structural library search strategy

Sugar structure similar in parent ion quality and mass spectrometry precursor ion quality to be identified is found out in sugared structural library, is then predicted The theoretical spectrum of these sugared structures, by the theoretical spectrum of prediction and mass spectrum to be identified one by one compared with, return to that similarity is highest theoretical to compose Corresponding sugar structure is as the corresponding sugared structure of mass spectrum to be identified.

Advantage: the candidate range of possible sugared structure is defined according to structural library, to reduce identification difficulty.

It is insufficient: a) prediction of the structure library searching dependent on the theoretical mass spectra of structure in library, and at present for sugared structure mass spectrum Forming Mechanism understanding still has limitation, causes theoretical mass spectra precision of prediction not high, affects qualification result to a certain extent Accuracy.B) library searching of structure is confined to the sugared structure in library, if the corresponding sugared structure of mass spectrum to be identified not in library, It is unable to get correct qualification result.

2) De Novo Structural Identification strategy

Different from structural library search strategy, De Novo strategy directly passes through pair independent of known sugared structural library The analysis of mass spectrometric data infers possible sugared structure using the m/z difference between spectral peak in spectrogram.

Advantage: for structure library searching, De Novo strategy is it can be found that the sugared structure being not present in structural library.

Defect: a) accuracy of .De Novo strategy identification depends critically upon the quality of mass spectrometric data.In the matter of high quality In modal data, each glycosidic bond can have corresponding quasi-molecular ions to occur;And in low-quality mass spectrum, part ion peak lacks It loses, causes De Novo strategy that can not obtain accurate qualification result.B) .De Novo needs to enumerate all possible sugared structure, Therefore efficiency is relatively low, identifies scale than relatively limited.

3) library searching strategy is composed

The second order ms of known sugars structure are stored in database in the form of " structure-mass spectrum " pair by spectrum library searching strategy In, it is then compared with mass spectrum to be identified and the true spectrum in database, returns to the corresponding sugar knot of the highest mass spectrum of similarity Structure is as qualification result.

Advantage: comparing more sugared structural library search strategy, composes and really composes known to library searching strategy use, rather than predicts Theoretical spectrum be compared so that the confidence level of qualification result is relatively high.

Defect: spectrum library searching strategy is only applicable to the sugared structure identified, then can not be true for the mass spectrum that do not identified Its fixed corresponding structure.

The information that second order ms provide is for the structure of saccharide compound complexity or has significant limitation, The saccharide compound based on second order ms is caused to identify that tactful accuracy is not high.Therefore, some researchers propose based on multistage matter Spectrum identification strategy is realized that is, using including more sugared structure fragmentation information in multi-stage ms data and promotes sugar Structural Identification Accuracy rate.It is existing it is a kind of based on multi-stage ms identification method be using known sugars structure second level and three-level mass spectrum construct " matter For spectrum-structure " to database, the method improves the accuracy of identification to a certain extent, but is composed in library due to it and compose quantity It is fewer, so can not still be identified well for some sugared structures.

Summary of the invention

The present invention provides a kind of sugared Structural Identification method and sugared Structural Identification device, to solve prior art DeNovo strategy The accuracy of identification depends critically upon the quality of mass spectrometric data and spectrum library searching strategy and the mass spectrum that do not identified can not be determined The defect of its corresponding structure.

To achieve the above object, the present invention provides a kind of sugared Structural Identification method, comprising steps of

Step 1: carrying out the corresponding minor structure of sugared structure spectral peak to be measured using multi-stage ms information and predict, the minor structure As candidate minor structure;And

Step 2: utilizing De Novo sugar Structural Identification technology, has been assembled according to the corresponding candidate minor structure of mass spectrum spectral peak Whole sugared structure.

Preferably, the step 1 includes:

Step 1: purification process being carried out to sugar-like product, mass spectrograph is injected, obtains first mass spectrometric, chosen in first mass spectrometric rich It spends highest quasi-molecular ions fragmentation and generates second order ms;

Step 2: according to the parent ion quality of second order ms, enumerating the monosaccharide type that may be formed and each type of list Sugared number obtains parent ion monosaccharide composition;And

Step 3: to spectral peak each in second order ms, enumerates possible corresponding ionic type and monosaccharide forms, and according to Parent ion monosaccharide composition is filtered to obtain the corresponding monosaccharide composition of each spectral peak, according to the corresponding monosaccharide composition piece of each spectral peak Lift possible candidate minor structure.

Preferably, the step 1 further include:

Step 4: if certain spectral peak corresponding monosaccharide composition is more than that scale is enumerated in setting in step 3, utilizing the spectral peak Generate next stage mass spectrum, spectral peak P3Corresponding monosaccharide composition is more than to enumerate scale, then assembles the spectral peak using next stage mass spectrum Corresponding candidate's minor structure;And

Step 5: utilize the next stage Information in Mass Spectra, execute step 2,3,4,5, until obtain all ion spectral peaks pair of mass spectrum The candidate minor structure answered.

Preferably, the step 2 includes:

Step 6:, will if there are laps between step 3 or the corresponding candidate minor structure of 5 obtained any two spectral peaks Two minor structures connect a line, do not connect side between the different candidate minor structures of the same spectral peak, are constructed according to spectral peaks all in mass spectrum The network of candidate minor structure;

Step 7: the construction debris in each path being assembled into a complete structure in the network;And

Step 8: if the corresponding quality of complete structure after assembling is equal to sugared structure parent ion to be measured in range of tolerable variance Quality, then it is assumed that find a sugar-like product candidate structure to be measured.

Preferably, the step 2 further include: step 9: circulation executes step 7, and it is corresponding to obtain all paths in network Complete structure, and sample to be tested candidate structure set is obtained according to step 8.

Preferably, the sugared Structural Identification method, further includes:

Step 10: using the matched quasi-molecular ions number of sugar-like product candidate structure to be measured found with step 8 as reciprocal fraction, And it is returned the structure of highest scoring as the candidate structure of sugar.

Moreover, to achieve the above object, the present invention also provides a kind of sugared identification apparatus, comprising:

User's web interactive interface;

Spectral peak candidate's minor structure identifies module, connect with the user web interactive interface, the spectral peak candidate minor structure mirror Cover half block includes:

Mass spectrometric data module: sugar-like product are handled to obtain first mass spectrometric using mass spectrograph, are chosen in first mass spectrometric The highest quasi-molecular ions fragmentation of abundance generates the second order ms data;And

Second order ms enumeration module: according to the parent ion quality of the second order ms, the monosaccharide type that may be formed is enumerated And monosaccharide number, obtain parent ion monosaccharide composition;To spectral peak each in second order ms, enumerating it may corresponding ionic type And monosaccharide composition, and be filtered to obtain the corresponding monosaccharide composition of each spectral peak according to parent ion monosaccharide composition, according to each The corresponding monosaccharide composition of spectral peak enumerates possible candidate minor structure;And

De Novo sugar Structural Identification module, comprising:

Candidate minor structure network constructs module: the candidate structure of second order ms enumeration module transmission is received, if arbitrarily There are laps between the corresponding candidate minor structure of two spectral peaks, then two minor structures are connected a line, the same spectral peak is different Do not connect side between candidate minor structure, constructs candidate minor structure network according to spectral peaks all in mass spectrum;

Assembling module: the construction debris in each path is assembled into a complete structure in the network;And

Candidate structure Quality estimation module: if assembling after the corresponding quality of complete structure in range of tolerable variance be equal to Survey sugared structure parent ion quality, then it is assumed that find a sugar-like product candidate structure to be measured, circulation executes step 7 and step 8, by net The corresponding possible sugar-like product candidate structure to be measured in all paths, constitutes sugar-like product candidate structure set to be measured, by this in network figure Sugar-like product candidate structure set to be measured returns to user web interactive interface.

Preferably, the spectral peak candidate minor structure identifies module further include:

Judgement and generation module: if certain spectral peak corresponding monosaccharide composition is more than enumeration module in second order ms enumeration module The second order ms of setting enumerate scale, then generate next stage mass spectrum using the spectral peak;And

Multi-stage ms enumeration module: according to the mass spectrographic parent ion quality of the next stage, the monosaccharide that may be formed is enumerated Type and monosaccharide number obtain parent ion monosaccharide composition;To each spectral peak in next stage mass spectrum, enumerating it may corresponding ion Type and monosaccharide composition, and be filtered to obtain the corresponding monosaccharide composition of each spectral peak according to parent ion monosaccharide composition, according to The corresponding monosaccharide composition of each spectral peak enumerates possible candidate minor structure, and the possible candidate minor structure is sent to candidate son Structural network figure constructs module.

Preferably, the De Novo sugar Structural Identification module further include:

Screening module: using with the matched quasi-molecular ions number of sugar-like product candidate structure to be measured that finds in assembling module as pair Score is answered, and returns to user web interactive interface for the structure of highest scoring as the candidate structure of sugar-like product to be measured.

The present invention is based on sugared structure multi-stage ms data to realize the mirror of sugared structure using De Novo sugar Structural Identification technology It is fixed.The accuracy for solving the identification of prior art De Novo strategy depends critically upon the quality and spectrum library searching plan of mass spectrometric data The defect of its corresponding structure can not be slightly determined for the mass spectrum that do not identified.Realize multi-stage ms De Novo sugar structure mirror Determine algorithm, by effectively utilizing multi-stage ms information, not only significantly improves De Novo and enumerate sugared structure fragment in the process Efficiency, and it has been obviously reduced sugared candidate structure set.

Below in conjunction with the drawings and specific embodiments, the present invention will be described in detail, but not as a limitation of the invention.

Detailed description of the invention

Fig. 1 a is prior art monosaccharide ring structure schematic diagram, wherein 1,2,3,4 and 6 corresponding C atom is the company of monosaccharide Connect site;Fig. 1 b is prior art monosaccharide glycosidic bond structural schematic diagram, wherein two monosaccharide connect to form 1-4 glycosidic bond;

Fig. 2 a to Fig. 2 d is a variety of representation schematic diagrames of prior art N-linked sugar GlcNAc2Man9 structure;

Fig. 3 is the sugared Structural Identification method and step figure of the present invention;

Fig. 4 is the sugared Structural Identification schematic device of the present invention;

Fig. 5 is the candidate result that 6 kinds of N-linked sugar is obtained using identification method of the present invention;

Fig. 6 utilizes spectral peak P3Next stage mass spectrum generate its corresponding candidate structure;

Fig. 7 is the sugared structure assembling process schematic diagram of the present invention.

Wherein, appended drawing reference:

1 user's web interactive interface

2 spectral peak candidate's minor structures identify module

21 mass spectrometric data modules

22 second order ms enumeration modules

23 judgements and generation module

24 multi-stage ms enumeration modules

3 De Novo sugar Structural Identification modules

31 candidate minor structure networks construct module

32 assembling modules

33 candidate structure Quality estimation modules

34 screening modules

Specific embodiment

The present invention constructs effective De Novo strategy, and the identification of sugared structure is realized in conjunction with multi-stage ms data, of the invention Sugared Structural Identification method mainly includes 2 aspects:

De Novo sugar structure packing algorithm: complete sugared structure is assembled according to the corresponding candidate minor structure of mass spectrum spectral peak. The present invention constructs network by the overlapping relation between each candidate minor structure, found out in figure can assemble it is complete The path of sugared structure.And

Multi-stage ms realize the prediction algorithm of the minor structure of sugared structure: since next stage mass spectrum includes upper level mass spectrum spectral peak All segment informations generated after corresponding minor structure fragmentation, so the comprehensive multi-stage ms information of the present invention carries out the minor structure of spectral peak Prediction, significantly improves the identification accuracy rate and efficiency of minor structure Candidate Set.

Wherein, De Novo sugar structure packing algorithm of the invention is according to the corresponding time of ion spectral peaks all in second order ms Minor structure is selected, network is constructed using the overlapping relation between different ions candidate's minor structure, matter after assembling is then found out in figure Amount is equal to the path of sugar-like product parent ion quality, specifically:

If 1, there are laps between the corresponding candidate minor structure of any two spectral peak, two minor structures are connected one Side does not connect side between the different candidate minor structures of same spectral peak, the network of minor structure segment is constructed according to spectral peaks all in mass spectrum Figure;

2, the construction debris in each path is assembled into a complete sugared structure in network, if after assembling The corresponding quality of sugared structure is equal to required sugared structure parent ion quality (in range of tolerable variance), then it is assumed that find a candidate sugar knot Structure;

3, using the quasi-molecular ions number of candidate sugared structure matching as reciprocal fraction, and using the sugared structure of highest scoring as sugar Candidate structure return.

Also, the complicated tree structure of sugared structure results in apparent isomerism, i.e., the same molecular mass pair The sugared structure answered may have very much, bring very big difficulty to carry out structure to De Novo and enumerate, seriously constrain De The identification scale of Novo.The present invention devises for the problem of existing De Novo identification scale deficiency and utilizes multi-stage ms information It realizes and the candidate structure of complicated spectral peak is identified, to promote the efficiency of De Novo identification.Multi-stage ms of the invention are realized The minor structure prediction algorithm of sugared structure are as follows:

1, purification process is carried out to sugar-like product, injects mass spectrograph, obtains first mass spectrometric, choose abundance most in first mass spectrometric High quasi-molecular ions fragmentation generates second order ms;

2, according to the parent ion quality of second order ms, the monosaccharide type that may be formed and each type of monosaccharide are enumerated Number;

3, to spectral peak each in second order ms, its possible corresponding ionic type and monosaccharide composition are enumerated, and according to mother Ion monosaccharide composition is filtered;

4, possible candidate minor structure is enumerated according to the corresponding monosaccharide composition of each spectral peak, if the corresponding monosaccharide group of spectral peak Scale is enumerated at more than setting, then generates next stage mass spectrum using the spectral peak, and go to 5, sees Fig. 6, spectral peak P3Corresponding list Sugar composition is more than to enumerate scale, then assembles the corresponding candidate minor structure of the spectral peak using next stage mass spectrum;

5, using next stage Information in Mass Spectra, 2,3,4,5 steps are executed, obtain the corresponding candidate son knot of all ion spectral peaks of mass spectrum Structure, and using sugared structure packing algorithm, assemble the candidate that the corresponding candidate minor structure of the spectrum composes corresponding spectral peak as upper level Minor structure.

Specifically, Fig. 3 is the method and step figure of sugared Structural Identification method of the invention, as shown in figure 3, side of the invention Method includes:

Step 1: carrying out the corresponding minor structure of sugared structure spectral peak to be measured using multi-stage ms information and predict, the minor structure As candidate minor structure;And

Step 2: utilizing De Novo sugar Structural Identification technology, has been assembled according to the corresponding candidate minor structure of mass spectrum spectral peak Whole sugared structure.

Wherein, the step 1 includes:

Step 1: purification process being carried out to sugar-like product, mass spectrograph is injected, obtains first mass spectrometric, chosen in first mass spectrometric rich It spends highest quasi-molecular ions fragmentation and generates second order ms;

Step 2: according to the parent ion quality of second order ms, enumerating the monosaccharide type that may be formed and each type of list Sugared number obtains parent ion monosaccharide composition;And

Step 3: to spectral peak each in second order ms, enumerating its possible corresponding ionic type and monosaccharide composition, and root It is filtered to obtain the corresponding monosaccharide composition of each spectral peak according to parent ion monosaccharide composition, be formed according to the corresponding monosaccharide of each spectral peak Enumerate possible candidate minor structure.

Preferably, the step 1 further include:

Step 4: if certain spectral peak corresponding monosaccharide composition is more than that scale is enumerated in setting in step 3, utilizing the spectral peak Next stage mass spectrum is generated, sees Fig. 6, spectral peak P3Corresponding monosaccharide composition is more than to enumerate scale, then corresponding next using the spectral peak Grade mass spectrum carries out the prediction of spectral peak candidate's minor structure, assembles the corresponding candidate minor structure of the spectral peak;And

Step 5: utilize the next stage Information in Mass Spectra, execute step 2,3,4,5, until obtain all ion spectral peaks pair of mass spectrum The candidate minor structure answered.

Wherein, the step 2 includes:

Step 6:, will if there are laps between step 3 or the corresponding candidate minor structure of 5 obtained any two spectral peaks Two minor structures connect a line, do not connect side between the different candidate minor structures of the same spectral peak, are constructed according to spectral peaks all in mass spectrum The network of candidate minor structure;

Step 7: the construction debris in each path being assembled into a complete structure in the network, sees Fig. 7, Fig. 7 It is the assembling process of identification method of the present invention, obtains the corresponding possible candidate minor structure of spectral peak in mass spectrogram by multi-stage ms, And whether the candidate minor structure network of building is overlapped according to candidate minor structure, then sugar-like product to be measured are obtained using the path in figure Corresponding candidate structure set and the corresponding marking (matched quasi-molecular ions number) of each candidate structure;And

Step 8: if the corresponding quality of complete structure after assembling is equal to sugared structure parent ion to be measured in range of tolerable variance Quality, then it is assumed that find a sugar-like product candidate structure to be measured;

Preferably, the step 2 further include:

Step: 10: using the matched quasi-molecular ions number of sugar-like product candidate structure to be measured found with step 8 as corresponding point Number, and returned the structure of highest scoring as sugar-like product candidate structure to be measured.

Also, preferably, the step 2 further include: step 9: circulation executes step 7, obtains all paths in network Corresponding complete structure, and sample to be tested candidate structure set is obtained according to step 8.

In addition, the invention also provides a kind of sugared identification apparatus, as shown in Figure 4, comprising:

User web interactive interface 1;

Spectral peak candidate's minor structure identifies module 2, connect with the user web interactive interface, the spectral peak candidate minor structure Identify that module includes mass spectrometric data module 21 and second order ms enumeration module 22, wherein

Sugar-like product are handled to obtain first mass spectrometric using tandem mass spectrometer, it is highest that abundance is chosen in first mass spectrometric Quasi-molecular ions fragmentation generates the second order ms data;And

Second order ms enumeration module 22 enumerates the monosaccharide type that may be formed according to the parent ion quality of the second order ms And monosaccharide number, obtain parent ion monosaccharide composition;To spectral peak each in second order ms, enumerating it may corresponding ionic type And monosaccharide composition, and be filtered to obtain the corresponding monosaccharide composition of each spectral peak according to parent ion monosaccharide composition, according to each The corresponding monosaccharide composition of spectral peak enumerates possible candidate minor structure;And

De Novo sugar Structural Identification module 3, including candidate minor structure network building module 31, assembling module 32 and time Select architecture quality judgment module 33, wherein

Candidate minor structure network constructs module 31: the candidate minor structure of second order ms enumeration module transmission is received, if There are laps between the corresponding candidate minor structure of any two spectral peak, then two minor structures are connected a line, the same spectral peak Do not connect side between different candidate's minor structures, constructs candidate minor structure network according to spectral peaks all in mass spectrum;

Assembling module 32: the construction debris in each path is assembled into a complete structure in the network;And

Candidate structure Quality estimation module 33: if the corresponding quality of complete structure after assembling is equal in range of tolerable variance Sugar structure parent ion quality to be measured, then it is assumed that find a sugar-like product candidate structure to be measured, circulation executes step 7 and step 8, will The corresponding possible sugar-like product candidate structure to be measured in all paths, constitutes sugar-like product candidate structure set to be measured in network.It will This sugar-like product candidate structure set to be measured returns to user web interactive interface;

Wherein, the spectral peak candidate minor structure identifies module further include:

Judgement and generation module 23: if certain spectral peak corresponding monosaccharide composition is more than enumerating mould in second order ms enumeration module The second order ms of block setting enumerate scale, then next stage mass spectrum are generated using the spectral peak, such as spectral peak P in Fig. 63Corresponding monosaccharide group At being more than to enumerate scale, then the corresponding candidate minor structure of the spectral peak is assembled using next stage mass spectrum;And

Multi-stage ms enumeration module 24: according to the mass spectrographic parent ion quality of the next stage, the monosaccharide that may be formed is enumerated Type and monosaccharide number obtain parent ion monosaccharide composition;To each spectral peak in next stage mass spectrum, enumerate its may it is corresponding from Subtype and monosaccharide composition, and be filtered to obtain the corresponding monosaccharide composition of each spectral peak, root according to parent ion monosaccharide composition Possible candidate minor structure is enumerated according to the corresponding monosaccharide composition of each spectral peak, the possible candidate minor structure is sent to candidate Minor structure network constructs module.

Preferably, the De Novo sugar Structural Identification module further includes screening module 34: by with assembling module in find The matched quasi-molecular ions number of sugar-like product candidate structure to be measured as reciprocal fraction, and using the candidate structure of highest scoring as sugar Candidate structure returns to user web interactive interface.

Embodiment: multi-stage ms De Novo N-linked sugar-like product Structural Identification

In order to verify the validity of sugared Structural Identification strategy of the invention, using the above method of the present invention to known N-linked Pure sugar-like product (coming from Ludger company) carry out multi-stage ms De Novo identification experiment, and laboratory apparatus is Shimadzu Corporation MALDI-IT-TOF mass spectrograph AXIMA Resonance.

Specific steps:

1) pure sugar-like product are injected mass spectrograph by after treatment, generate first mass spectrometric, and molecular mass is pressed in first mass spectrometric Spectral peak, which is corresponded to, in selection first mass spectrometric generates second order ms.

2) enumerates possible parent ion monosaccharide composition according to the parent ion quality of second order ms.

3) enumerates the possible ionic type of all spectral peaks in second order ms and monosaccharide composition, and according to parent ion monosaccharide group It is formed at the corresponding monosaccharide of each spectral peak is obtained by filtration, and enumerates the corresponding candidate minor structure of generation.

4) the monosaccharide type and monosaccharide number that if the corresponding monosaccharide composition of spectral peak includes are relatively more, the spectrum is utilized Peak generation next stage mass spectrum, repetition step 2,3,4 and 5, the corresponding candidate minor structure of the spectral peak is obtained, as shown in Figure 6.

5) constructs candidate minor structure network, any two according to the corresponding candidate minor structure of the corresponding spectral peak of second order ms There are laps between the corresponding candidate minor structure of spectral peak, then two minor structures are connected a line, the different candidate sons of the same spectral peak Do not connect side between structure.

6) obtains sugar-like product candidate structure set to be measured according to candidate minor structure network, and is matched according to candidate structure Quasi-molecular ions number gives a mark to the candidate structure in candidate structure set, using the corresponding candidate structure of score value as sugar-like to be measured The candidate structure of product returns.

Fig. 5 shows the experimental result of 6 kinds of N-linked sugar.First row indicates known N-linked sugar sample ID, Secondary series indicates the corresponding real structure of sugar, and third column indicate the sugar-like product candidate structure to be measured that strategy obtains through the invention Number, the 4th is classified as the correspondence sugar-like product candidate structure to be measured that strategy of the present invention obtains.

Interpretation of result:

1) identify that strategy can obtain the candidate structure of sugar-like product to be measured using multi-stage ms De Novo of the invention.

2) sugar-like product candidate structure set to be measured can be limited in the scale of a very little by present invention identification strategy.

Technical effect

The present invention obtains sugared structure time to be measured using the multi-stage ms data of oligosaccharides as input, by using enumerating and assembling It selects structured set as output, can be applied to the prediction of sugared structure candidate collection to be measured, realize multi-stage ms De Novo sugar Structural Identification algorithm not only significantly improves De Novo and enumerates sugared structure in the process by effectively utilizing multi-stage ms information The efficiency of segment, and it has been obviously reduced sugared candidate structure set.

Certainly, the present invention can also have other various embodiments, without deviating from the spirit and substance of the present invention, ripe Various corresponding changes and modifications, but these corresponding changes and modifications can be made according to the present invention by knowing those skilled in the art It all should belong to the protection scope of the claims in the present invention.

Claims (8)

1. a kind of sugar Structural Identification method, which is characterized in that comprising steps of
Step 1: carrying out the corresponding minor structure of sugared structure spectral peak to be measured using multi-stage ms information and predict, the minor structure conduct Candidate minor structure;And
Step 2: utilizing De Novo sugar Structural Identification technology, is assembled completely according to the corresponding candidate minor structure of mass spectrum spectral peak Sugared structure;
Wherein,
The step 1 includes:
Step 1: purification process being carried out to sugar-like product, mass spectrograph is injected, obtains first mass spectrometric, chooses abundance most in first mass spectrometric High quasi-molecular ions fragmentation generates second order ms;
Step 2: according to the parent ion quality of second order ms, enumerating the monosaccharide type that may be formed and each type of monosaccharide Number obtains parent ion monosaccharide composition;
Step 3: to spectral peak each in second order ms, enumerate may corresponding ionic type and monosaccharide composition, and according to mother from Sub- monosaccharide composition is filtered to obtain the corresponding monosaccharide composition of each spectral peak, and being enumerated according to the corresponding monosaccharide composition of each spectral peak can The candidate minor structure of energy.
2. sugar Structural Identification method according to claim 1, which is characterized in that the step 1 further include:
Step 4: if certain spectral peak corresponding monosaccharide composition is more than that scale is enumerated in setting in step 3, being generated using the spectral peak Next stage mass spectrum assembles the corresponding candidate minor structure of the spectral peak using next stage mass spectrum;And
Step 5: utilize the next stage Information in Mass Spectra, execute step 2,3,4,5, until obtain all ion spectral peaks of mass spectrum it is corresponding Candidate minor structure.
3. sugar Structural Identification method according to claim 2, which is characterized in that the step 2 includes:
Step 6: if there are laps between step 3 or the corresponding candidate minor structure of 5 obtained any two spectral peaks, by two Minor structure connects a line, does not connect side between the different candidate minor structures of the same spectral peak, is constructed according to spectral peaks all in mass spectrum candidate The network of minor structure;
Step 7: the construction debris in each path being assembled into a complete structure in the network;And
Step 8: if the corresponding quality of complete structure after assembling is equal to sugared structure parent ion quality to be measured in range of tolerable variance, Then think to find a sugar-like product candidate structure to be measured.
4. sugar Structural Identification method according to claim 3, which is characterized in that the step 2 further include: step 9: follow Ring executes step 7, obtains the corresponding complete structure in all paths in network, and obtain sample to be tested candidate knot according to step 8 Structure set.
5. sugar Structural Identification method according to claim 3, which is characterized in that further include:
Step 10: using the matched quasi-molecular ions number of sugar-like product candidate structure to be measured found with step 8 as reciprocal fraction, and will The structure of highest scoring is returned as the candidate structure of sugar.
6. a kind of sugar identification apparatus, the sugared Structural Identification method for claim 3 characterized by comprising
User's web interactive interface;
Spectral peak candidate's minor structure identifies module, connect with the user web interactive interface, and the spectral peak candidate minor structure identifies mould Block includes:
Mass spectrometric data module: sugar-like product are handled to obtain first mass spectrometric using mass spectrograph, abundance is chosen in first mass spectrometric Highest quasi-molecular ions fragmentation generates second order ms data;
Second order ms enumeration module: according to the parent ion quality of the second order ms, enumerate may composition monosaccharide type and Monosaccharide number obtains parent ion monosaccharide composition;To spectral peak each in second order ms, enumerate its may corresponding ionic type and Monosaccharide composition, and be filtered to obtain the corresponding monosaccharide composition of each spectral peak according to parent ion monosaccharide composition, according to each spectral peak Corresponding monosaccharide composition enumerates possible candidate minor structure;
De Novo sugar Structural Identification module, comprising:
Candidate minor structure network constructs module: the candidate structure of second order ms enumeration module transmission is received, if any two There are laps between the corresponding candidate minor structure of spectral peak, then two minor structures are connected a line, and the same spectral peak is different candidate Do not connect side between minor structure, constructs candidate minor structure network according to spectral peaks all in mass spectrum;
Assembling module: the construction debris in each path is assembled into a complete structure in the network;And
Candidate structure Quality estimation module: if the corresponding quality of complete structure after assembling is equal to sugar to be measured in range of tolerable variance Structure parent ion quality, then it is assumed that find a sugar-like product candidate structure to be measured, circulation executes step 7 and step 8, by network In all paths it is corresponding may sugar-like product candidate structure to be measured, constitute sugar-like product candidate structure set to be measured, this is to be measured Sugar-like product candidate structure set returns to user web interactive interface.
7. sugar identification apparatus according to claim 6, which is characterized in that the spectral peak candidate minor structure identifies module further include:
Judgement and generation module: if certain spectral peak corresponding monosaccharide composition is more than that enumeration module is arranged in second order ms enumeration module Second order ms enumerate scale, then using the spectral peak generate next stage mass spectrum;And
Multi-stage ms enumeration module: according to the mass spectrographic parent ion quality of the next stage, enumerate may composition monosaccharide type with And monosaccharide number, obtain parent ion monosaccharide composition;To each spectral peak in next stage mass spectrum, enumerating it may corresponding ionic type And monosaccharide composition, and be filtered to obtain the corresponding monosaccharide composition of each spectral peak according to parent ion monosaccharide composition, according to each The corresponding monosaccharide composition of spectral peak enumerates possible candidate minor structure, and the possible candidate minor structure is sent to candidate minor structure Network constructs module.
8. sugar identification apparatus according to claim 6, which is characterized in that the De Novo sugar Structural Identification module further include:
Screening module: will be with the matched quasi-molecular ions number of sugar-like product candidate structure to be measured found in assembling module as corresponding point Number, and user web interactive interface is returned using the structure of highest scoring as the candidate structure of sugar-like product to be measured.
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