JP2006514299A - Enzyme arrays and assays - Google Patents

Abstract

The present invention relates to mass spectrometers, particularly enzyme arrays and assays for use with laser desorption / ionization such as, but not limited to, MALDI mass spectrometers. The present invention provides a process for providing a probe carrying an immobilized enzyme, optionally introducing a test compound, optionally introducing a test compound, and reacting one or more reactants with the immobilized enzyme. Introducing in sufficient time and form, drying the probe, subjecting the probe to mass spectrometry, and the presence and / or absence of one or more products and / or one or more reactants. A method of determining the enzyme activity or the effect of the test compound on the enzyme activity using mass spectrometry, comprising the step of determining the activity of the enzyme or the effect of the test compound on the enzyme activity by detecting , A representative example for kinase assays. The present invention also provides an array for use in the method.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application includes GB03111946.8 filed on May 23, 2003, GB0224872.2 filed on October 25, 2002, and PCT / filed filed on December 20, 2002. The priority of EP02 / 14859 is claimed and each is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION This invention relates to enzyme arrays and assays, and more particularly to mass spectrometers, and kinase arrays for use with laser desorption / ionization mass spectrometers such as, but not limited to, MALDI mass spectrometers. And the assay.

  In recent years, it can be seen that the number of proteomics applications for mass spectrometry has increased. Analytical methods used in proteomics are mainly based on two-dimensional gel electrophoresis for protein separation and mass spectrometry for protein identification or Edman degradation. Limitations to two-dimensional gel electrophoresis include relatively poor resolution, sensitivity, and reproducibility. As a result, two-dimensional gel electrophoresis such as isotope-coded affinity label (ICAT) (Non-Patent Document 1), tandem affinity protein (TAP) (Non-Patent Document 2) purification, and use of protein microarray (Non-Patent Document 3). Proteomics methods that avoid this are gaining popularity.

  In addition, these new methods extend the scope of proteomics from the collection and classification of differential expression data to the stage where intermolecular relationships can be assigned, which is referred to as functional proteomics. Protein microarrays have recently been used to analyze the major fractions of 119 yeast kinase (Non-Patent Document 4) and yeast proteome (Non-Patent Document 5).

Protein microarrays have been analyzed by enhanced chemiluminescence (ECL), fluorescent or radioactive labels, or antibody-based detection systems, but to date have not been analyzed by mass spectrometry.
Gygi, SP, Rist, B., Gerber, SA, Turecek, F. Gelb, MH and Aebersold, R ,. Nat Biotechnol. 1999; 17,994-999 Gavin AC, Bosche M, Krause R, Grandi P, Marzioch M, Bauer A, Schultz J, Rick JM, Michon AM, Cruciat CM, Remor M, Hofert C, Schelder M, Brajenovic M, RuffnerH, Merino A, Klein K, Hudak M, Dickson D, Rudi T, Gnau V, Bauch A, Bastuck S, Huhse B, Leutwein C, Heurtier MA, Copley RR, Edelmann A, Querfurth E, Rybin V, Drewes G, Raida M, Bouwmeester T, Bork P , Seraphin B, Kuster B, Neubauer G, Superti-Furga G., Nature 2002; 415 (6868), 141-147. MacBeath, G., and Schreiber, SF Science 2000; 289,1760-1763 Zhu H, Klemic JF, Chang S, Bertone P, Casamayor A, Klemic KG, Smith D, Gerstein M, Reed MA, Snyder M. Nat Genet. 2000; 26 (3): 283-9 Zhu H, Bilgin M, Bangham R, Hall D, Casamayor A, Bertone P, Lan N, Jansen R, Bidlingmaier S, Houfek T, Mitchell T, Miller P, Dean RA, Gerstein M, Snyder M. Science 2001; 293, 2101-2105

  The current dependence on using ligands or labeled probes such as labeled antibodies to analyze protein microarrays places constraints on the use of protein microarrays. Therefore, a detection system that does not use sensitive labels would be greatly advantageous, and if the labeled compound is either not available or too expensive, or if the label would radically change the nature of the ligand The scope of application will be expanded to. Such label-free methods are particularly useful in the early stages of drug discovery where a large number of compounds are screened for proteins.

  With such a mass spectrometry probe on which an enzyme microarray is fabricated on a probe, the effects of enzyme reactions and compounds on the enzyme reaction can be investigated in a manner that does not use labels by desorption and ionization of reactants and products. It becomes possible to do. Probes and methods are particularly useful for drug discovery processes such as hit series evaluation, lead optimization, prognostic toxicogenomics, and metabolite profiling.

  However, the probes and methods could be used as diagnostic tools for both diagnosing disease states and monitoring disease progression.

Means for Solving the Invention

  According to the first aspect of the present invention, i) providing a probe carrying an immobilized enzyme, ii) optionally introducing a test compound, iii) reacting one or more reactants. Introducing into the immobilized enzyme in sufficient time and form, iv) drying the probe, v) applying mass spectrometry to the probe, and vi) one or more products and / or one or more reactions. Determining the effect of the test compound on the enzyme activity or enzyme activity comprising determining the effect of the test compound on the enzyme activity or enzyme activity by detecting the presence and / or absence of the product. A method of determining using analysis is provided.

  For mass spectrometry, a MALDI mass spectrometer is preferably used. However, in principle, the analytical requirement for mass spectrometry is that the molecules are converted to gaseous ions, so that those skilled in the art will know that laser desorption ionization mass spectrometry, matrix-assisted laser desorption ionization (MALDI) mass spectrometry. Many other mass spectrometry methods that enable this ionization event, including but not limited to, desorption on silicon (DIOS) mass spectrometry, electrospray ionization mass spectrometry, and atmospheric pressure ionization (API) mass spectrometry It will be appreciated that can also be used. It is clear that Fourier transform mass spectrometry (FT / MS) methods such as Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry can be used to increase the mass accuracy of various ionization methods.

  For example, in the case of electrospray ionization, the enzyme is immobilized on individual nozzles of a multi-nozzle spray probe (eg, Nano Mate-100 nanoelectrospray probe sold by Advion). The reaction can be carried out by introducing one or more reactants into each nozzle, introducing a probe into the spectrometer, and ionizing the reactants and products by electrospray ionization.

Using the method, any enzymatic reaction in which one or more reactants are converted to one or more products and any of the reactants and / or products can be identified using, for example, MALDI mass spectrometry. Although all kinases can be studied, nucleotide triphosphates (NTP) or nucleotide diphosphates (NDP) (eg, adenine triphosphate (ATP) or adenine diphosphate) that can be easily and distinguishably detected Acid (ADP)) is used and / or produced, and the method is particularly suitable as a method for testing kinases. Other nucleotide species such as guanine, uridine, and cytosine could also be used, but due to the fact that adenine provides a more sensitive assay that can be detected at pico ( ^10-12 ) molar levels, Those skilled in the art understand that this is preferred. The use of MALDI mass spectrometry improves sensitivity because the effect of the matrix is increased.

  In one embodiment, step ii) is essential, and the effect that the test compound has on enzyme activity is determined by comparison with the results obtained in the absence of the test compound. Assays can be performed on a single array by performing two or more assays in parallel or comparing to a standard. The test compound can be added before the one or more reactants, after the reactants, and most preferably with the reactants.

  The method can be used to provide qualitative or quantitative results.

  The method preferably uses MALDI mass spectrometry to determine the activity of one or more kinases or the effect a test compound has on the activity of one or more kinases. Thus, an array of kinases for use in the method comprises at least 10 to 25, 50, 75, 100, 200, 300 or more of one or more kinases, eg, more than 500 kinases of the same function. Can be contained. These can be arranged on a microarray in which each kinase is deposited in a separate target region.

  In the kinase assay, the one or more reactants can include a phosphate donor, a phosphate acceptor, and a divalent cation. The phosphate donor can be a phosphorylated substrate and the phosphate acceptor can be a nucleotide diphosphate (NDP). The simplicity of the method lies in the fact that these reactants are common to all kinase reactions and therefore only one set of conditions can be applied to various kinases. This means that the assay is powerful and can be used for high-throughput screening.

  It is of course possible to use separate and generic substrates, examples of kinases and their substrates are shown in Tables 1 and 2 attached hereto.

In one embodiment, the phosphate donor is a nucleotide triphosphate (NTP) and the phosphate acceptor is a substrate that is phosphorylated. The divalent cation (M ²⁺ ) is preferably magnesium or manganese.

  In another embodiment, the product is a nucleotide triphosphate or nucleotide diphosphate and the presence is detected. Since a typical kinase reaction is reversible, of course, the reactant can be a product and vice versa.

Typical reaction: (reactant) (product)
For example, glucose + ATP → glucose hexaphosphate + ADP
Hexokinase / Mg ²⁺
(Product) ← (Reactant)

Typically, nucleotide triphosphates or nucleotide diphosphates are detected as [NTP] ⁻ or [NDP] ⁻ and / or as a peak of one or more of their addition products. One or more adduct product peaks are typically adduct product peaks with monovalent cations (M ⁺ ) (eg, Na, K, Li) depending on the reagent / buffer used. . One or more adduct product peaks may be, for example, [ATPM] ⁻ , [ATPM ₂ ] ⁻ , and [ATPM ₃ ] ⁻ and / or [ADPM] ⁻ , [ADPM ₂ ] ⁻ , and [ADPM ₃ ]. ^- can contain.

  An important factor for good detection is the choice of low salt buffer. The low salt buffer is preferably a “semivolatile buffer” such as an ammonium bicarbonate buffer. Such a buffer is converted to a gas upon volatilization (in the case of ammonium bicarbonate, it is ammonia, carbon dioxide, and water), leaving no residue. Alternatively, the reaction mixture only needs to be a “low salt” buffer at the evaporation / ionization point, so use a buffer containing a higher concentration of semi-volatile salt and then semi-volatile after the end of the reaction It may be possible to remove the buffer in vacuum (either in a mass spectrometry vacuum chamber or in an external vacuum chamber). However, this is more complex and less desirable.

  A further significant feature of the present invention is that in the kinase assay, the detected product / reactant is small, typically less than 1000 daltons, so that the probe need not be overcoated with energy absorbing molecules (matrix) The fact is that mass spectrometry can be performed. This simplifies and speeds up procedures and cost savings. However, the addition of matrix increases sensitivity.

  If energy absorbing molecules are applied, they must be applied to the probe in the area where the immobilized enzyme is used.

  It is preferred to introduce one or more reactants and, if present, the test compound into the immobilized enzyme in a compartmentalized form, such as a droplet form. The droplets preferably have a volume of less than 1 microliter.

  Furthermore, it is preferred to perform the assay in a humid environment.

  Of course, the method of the present invention can be applied not only to kinases but also to other enzymes. Thus, whenever the reactants and / or products are ionizable, and when the mass of the reactants and / or products changes due to the enzymatic reaction, the enzymatic reaction of the immobilized protein on the protein array Can be studied by mass spectrometry. This can be the case for oxidoreductases, transferases, hydrolases, lyases, and ligases.

  Typical enzyme subclasses of these enzyme groups are listed in Table 1 below.

Alternatively, using the method, NAD, NADP, NADH, NADPH, ATP, GTP, UTP, CTP, UDP-glucose, UDP-glucosamine, UDP-galactose, pyridoxalphosphate, UDP-N-acetyl-D-glucosamine, GDP -D-mannose, dTDP-6-deoxy-L-mannose, GDP-6-deoxy-D-talose, UDP-N-acetylmuramic acid, S) -3-hydroxyacyl-CoA, S-adenosyl-L- Methionine, acetyl-CoA, L-selenoceryl-tRNA ^Sea , (S) -3-hydroxy-3-methylglutaryl-CoA, 5,10-methylenetetrahydrofolate, ascorbate, 2-oxoglutamate, glutathione, pyruvate, and Complements containing tetrahydropteridine The enzymatic reaction with the quality (and reaction in connection with the present application) can be monitored.

  This is particularly useful when the substrate or product is not ionizable or the reaction does not cause a mass change, as seen with isomerases (eg, phenylalanine racemase that hydrolyzes ATP). Typical isomerases are listed in Table 4.

  More specifically, enzymes include protein kinases (including serine / threonine kinases and tyrosine kinases), proteases (including serine proteases, cysteine proteases, aspartyl proteases, and metalloproteinases), carboxylases, esterases, phosphodiesterases, protein phosphatases. From one or more groups of enzyme families that are common drug targets, including tyrosine phosphatases, G-protein coupled receptors, ATP-dependent chaperones, cyclooxygenases, cytochrome P450s, sialidases, and short chain dehydrogenases / reductases To be elected.

  According to a further aspect of the invention, for use in a mass spectrometer comprising a support having an electrically conductive target surface, the target surface comprising an array having a plurality of enzymes immobilized thereon Providing a probe for

  In a preferred embodiment, the enzyme is selected from the group of enzymes listed above. The enzyme family that is a common drug target is particularly preferred, although specifically, but not limited to kinases.

  The array is preferably a microarray.

  The enzyme is typically preferably bound to the probe as a fusion protein via a label such as biotin or a sh ble protein, for example.

  Related aspects to the present invention are well described in many of the applicant's prior patent applications, including WO 01/57198, and thus are not dealt with extensively herein, but others such as GB0224872.2. Is not yet published, so further support and related details are given below.

  Accordingly, probes referred to herein include microarrays and arrays in which protein spots are visible to the naked eye, which probes include, but are not limited to, laser desorption / ionization mass spectrometry, It is adapted to be investigated by matrix assisted laser desorption / ionization (MALDI).

  Further aspects related to the present invention include methods of making such probes that can be investigated by laser desorption / ionization mass spectrometry, specifically matrix-assisted laser desorption / ionization (MALDI), and such probes or Protein microarray analysis methods are included.

  Thus, the development of MALDI MS compatible protein microarrays (the term includes enzyme microarrays) was complicated because existing protein microarray formation methods did not readily migrate to MALDI targets. There are many reasons why this is true, including the specific nature of the probe surface and the possibility that salts present in the reaction buffer will interfere with the detection method.

Procedures known in the MALDI art typically require co-crystallization of an aqueous analyte with an acidic energy absorbing molecule or “matrix” to promote ionization of the analyte (Karas and Hillenkamp , 1988). As is known in the art, analyte and matrix co-crystallization methods for MALDI typically result in a heterogeneous crystallization process, each containing a separate and spatial amount of matrix and analyte. Result in distant crystals. As a result, it is often observed that individual crystals do not contain enough analyte for analysis by MALDI. This, in turn, necessitates the analyzer to sample a number of distinct locations (ie, 10-100 or more) within a given target area to obtain a good analyte signal. This is sometimes referred to as “sweet spot search”. Because of this, it was necessary for the protein spot to be large, so that miniaturization was previously prevented. The protein spots are generally of the order of at least 0.5 mm ^2.

  In order to create a MALDI MS-compatible protein microarray, a solution to the aforementioned disadvantages of the prior art, which allows both the miniaturization of the target area and the functional analysis of the arrayed protein, was required.

  As defined herein, a probe is a support that can serve as a target in analysis by laser desorption / ionization mass spectrometry, eg, matrix-assisted laser desorption / ionization (MALDI). The probe carries an enzyme, eg, a kinase, and a reactant (and optionally a test compound) is added. After a time sufficient for the reaction to take place and a product is formed, the probe is dried and subjected to mass spectrometry. Repeller lenses for ion optics assemblies found in laser desorption / ionization time-of-flight (TOF) mass spectrometers in the art so that reactants and / or products can be converted to gaseous ions for analysis. Interacts with (repeller lens). For example, high affinity protein binding moieties such as streptavidin, avidin, or neutravidin molecules are known in the art that have been treated to be present on the probe surface to which a biotinylated enzyme is attached for later analysis. The probe of the present invention can be obtained from a target for MALDI analysis. For example, conventional glass or gold MALDI targets can be used.

  As defined herein, a microarray is an array in which the size of discrete target areas, ie individual areas probed by a laser, is on the order of less than a micrometer. At the upper scale limit of about 100 micrometers, they may be visible with the naked eye, and at the lower scale limit, distinct target areas are not clearly distinguished with the naked eye.

The array can typically be arranged in a matrix comprising several columns and columns. Although the number of distinct target regions depends on what is being screened, it is generally desirable to have a high density of these distinct regions on the probe surface as this facilitates high throughput screening. Typically, a probe comprises at least 10, more preferably at least 100, more preferably at least 1000, and 10,000 or more target regions formed thereon (typically a probe surface has an area of about 10,000 mm ^2, Bruker (Bruker) probe has a region of 10,292Mm ^2, it is not necessary to use the entire resin or probe, in one or more matrices thereon microarray Can be granted). The actual density in a given matrix depends on the size of the distinct target areas (typically printed as spots) and the spacing between adjacent spots. Thus, distinct target areas typically exist at a density of two or more distinct target areas per mm ² within any matrix.

  The enzyme is the part where the reaction takes place.

  As used herein, the term “enzyme” is used to include the entire enzyme and its subunits or domains.

  As used herein, “fusion protein” is used to refer to an enzyme having a label attached to the enzyme, such as a biotinylated consensus sequence or a phleomycin / zeocin resistant binding protein.

  A “linker molecule” is a molecule that functions as its name suggests. It is a molecule that contains functional groups that allow cross-linking to be formed between different molecules.

  Another significant development that allows "miniaturization" of enzyme arrays formed on MALDI targets results from applying Applicant's COVET technology described in WO 01/57198. Simply put, this technique can be used to create them in a specific orientation on a microarray surface from cDNA library-expressing enzymes that carry “sequence tags” that can be used to supplement enzymes with high affinity. . This firstly allowed stable immobilization of an enzyme, eg a kinase library, avoiding leaching of the enzyme from the surface, and secondly the orientation of the fusion protein on the surface. Immobilization makes it possible to ensure maximum biological activity.

  Yet another significant aspect of the present invention when compared to current protein microarrays is the provision of such probes having an electrically conductive surface. This surface, including the semiconductor surface, is essential when the probe is subjected to MALDI MS analysis. The support could all be made of an electrically conductive material (the term is used herein to include a semiconductor material), while any suitable metal such as silver, platinum, Iridium, tungsten, copper, cobalt, nickel, and iron, or mixtures thereof, or semiconductors such as silicon oxide, graphite, or germanium oxide could be used, but glass with an electrically conductive material such as gold It is preferable to coat a hard support such as.

  If probes or enzyme microarrays are made, for example, on standard size microscope glass slides, they can be mounted in adapters that carry them to the mass spectrometer. Such an adapter is described in Applicant's co-pending UK application 0216387.1.

  Further significant development and what can be seen independently of the specific applications described herein is that the Applicant has solved the problem caused by non-specific protein binding. Applicants have solved this particular problem by providing a layer on the probe surface that is resistant to non-specific protein binding. More specifically, the microarray surface was modified by including a molecular layer that rejects the protein. These protein excretion molecules, including, for example, polyethylene glycol, are easily attached to, for example, a glass or gold surface so that they protrude from the probe surface, and their amino side chains or carboxyl side groups are used to convert them to protein excretion molecules. It can be attached to the probe surface via a linker such as a polyamino acid that can be attached. Those skilled in the art are well aware that other functional molecules could be used. It is preferred to introduce the enzyme binding moieties at the position where they extend from the surface. Preferred enzyme binding moieties include, for example, biotin, biotin-neutravidin, and bleomycin, and these and other moieties are either functional groups on the linker molecule and / or functional groups on the protein excretion molecule. Can be introduced into the layer. Typically, the affinity capture moiety is introduced in a small proportion (typically less than 20%) relative to the protein excretion molecule.

  Thus, Applicants have not only been able to introduce the enzyme capture moiety in a uniform and spatially partitioned sequence, but also in a manner that allows high affinity binding in a specific manner. . The resulting surface combines selectivity for capture of biopolymers on the probe with reduced non-specific binding of the type often observed on non-derivatized glass or metal surfaces, and further capture It produces a uniform distribution and / or orientation of the biopolymer.

  Component molecules responsible for eliminating non-specific proteins generally include molecules that are inherently hydrophilic. This includes, for example, polymers such as polyethylene glycol, dextran, polyurethane, and polyacrylamide, and self-assembled monolayers (SAM). The polymer preferably includes one or more functional side groups through which the protein capture moiety can be attached. In the case of polyethylene glycol, the functional group is a hydroxyl group. Molecules responsible for rejecting non-specific proteins can be bound directly to the surface, for example as in SAM, or can be bound via a linker. Polyamino acids such as poly L lysine, poly L aspartic acid, poly L glutamic acid, or mixtures thereof are particularly preferred linkers.

  These have an amino side chain or a carboxy side chain, through which the molecules responsible for rejecting non-specific proteins can be bound, because the side chain further binds a protein capture moiety Can be used. In addition or in addition, the protein capture moiety can be bound via component molecules responsible for excreting specific proteins.

  FIG. 1 illustrates the binding of such molecules and the defined orientation that can be achieved by this sequential binding compared to that achieved using current antibody binding techniques that produce random binding. Contrast.

  In a preferred embodiment, the probe has either a biotin binding agent, such as neutravidin, avidin, or streptavidin, or a bleomycin resistant protein binding agent, such as bleomycin, because it is an enzyme capture moiety. . By printing multiple bacterial, yeast, sf9, or mammalian cell lysates containing fusion proteins in which high affinity labels, such as biotin or zeocin resistance protein (ZRP), are expressed on the capture surface Bind to the probe to create a protein microarray. Proteins are derived from expression of cDNA libraries, and each individual clone is labeled with a consensus sequence at the C-terminus and / or N-terminus, which allows high affinity recognition of the enzyme even in the presence of other protein excretion molecules It becomes. Only the recombined and labeled enzyme will recognize the capture surface, and other proteins from the lysate will not bind to the protein excretion surface and will have high affinity for the protein binding portion present in the layer. Since it does not have, it can be washed away.

  A further aspect of the present invention provides a method for making an enzyme microarray for use in a mass spectrometer, comprising the steps of providing a probe of the present invention and depositing an enzyme in a separate target region at the area of use of the protein capture moiety. I will provide a.

  A further aspect of the present invention is a probe of the present invention that deposits energy absorbing molecules in a manner that denatures the enzyme, thus unbinding the enzyme from the protein binding moiety and leaving the denatured enzyme unbound on the surface. Provides an analysis method.

  The energy absorbing molecules form a uniform crystalline layer at distinct locations in the protein capture moiety and the area of use of the captured enzyme.

  The uniform crystal layer is substantially continuous so that the individual crystals are not visible at a magnification of 100 and there are no visible cracks. It also has a substantially uniform depth so that there is no apparent change in crystal size at 100 times magnification.

  The energy absorbing molecules are deposited on the surface in a non-aqueous solvent and the non-aqueous solvent is evaporated away. The non-aqueous solvent is preferably an organic solvent such as acetone or butanone. The non-aqueous solvent preferably includes a modifier that adjusts the evaporation rate so that crystallization of the energy absorbing molecules occurs on the probe. Suitable modifiers include glycerol, polyethylene glycol, and thioglycerol. The energy absorbing molecule is a mixture of 80-99.9%, preferably 99% organic solvent, for example acetone and 20-0.1%, preferably 1% regulator, for example glycerol (vol / vol). It is preferable to deposit in. Typical energy absorbing molecules include α-cyano-4-hydroxy-cinnamic acid, sinapinic acid, gentisic acid, nifidine, succinic acid, 1,8,9, -anthracentriol, 3-indoleacrylic acid, Includes crystals of 2- (hydroxyphenylazo) benzoic acid, 4-nitroaniline, and combinations thereof.

  It is preferred that the energy absorbing molecules are deposited in the protein usage region and each protein spot is overcoated with an energy absorbing molecule spot of similar size.

  In order to achieve individual high density samples on the microarray, it is necessary to arrange the energy absorbing molecules on the surface in microcrystals. The matrix can form a uniform layer of flat crystals without significant breaks between the crystals and can be deposited on the microarray in very small amounts.

  In contrast to the prior art, where the matrix and analyte are co-crystallized in an aqueous solvent, the applicant first deposits the protein in an aqueous solvent and then moves the energy absorbing molecule from the non-aqueous solvent onto the probe. Two separate steps were used, the step of depositing to crystallize. This has the advantage that the protein is deposited in its biological form. However, by using a non-aqueous solvent to deliver the energy absorbing molecules, a uniform microcrystalline layer can be formed. This has two advantages. First, the formation of a uniform layer means that there is no need to search for sweet spots because the uniform layer ensures that the protein is obtained in the presence of energy absorbing molecules, and secondly, Thereby, the measurement is more accurate due to the equal nature of the layers.

[Example 1]
Referring to FIG. 2, ATP was enzymatically synthesized from the reaction of ADP, creatine phosphate, and creatine kinase (also known as creatine phosphokinase) in 25 mM ammonium bicarbonate at pH 7.4. [ADP] ⁻ was detected at 427.6 daltons and [ADP + Na] ⁻ was detected at 449.6 daltons. The products of the creatine phosphate kinase reaction were detected at 507.6, 529.6, 551.6, and 573.8 and [ATP] ⁻ as well as three ATP sodium adducts [ATPNa] ⁻ , [ATPNa ₂ ] ⁻ and [ATPNa ₃ ] ⁻ were in good agreement with the predicted molecular weight.

  Control reactions omitting either ADP or creatine phosphate substrate or creatine phosphate kinase enzyme did not show ATP peaks.

[Example 2]
Referring to FIG. 3, this example demonstrates biotinylation, capture, and desalting of creatine kinase from rabbit muscle on a probe coated with PEG-PLL-biotin-neutravidin for analysis by MALDI mass spectrometry. As well as the enzyme activity of immobilized kinase using MALDI mass spectrometry.

Materials: Creatine kinase from rabbit muscle, ATP, creatine N- phosphotransferase, ADP, creatine phosphate, 1mM Tris _{HCl (pH7.5), 1mM MgCl 2} , gold coated glass slide, PEG-PLL-Biotin , Neutravidin

  Solution: Washing buffer: 1 mM Tris-HCl (pH 7.5) containing 0.1% Triton X-100; Desalting buffer: 1 mM Tris-HCl (pH 7.5)

Synthesis of affinity capture polymer Poly-L-lysine PEG-biotin (PEG-PLL-biotin) was obtained from Ruiz Taylor (Natsume, T., Nakayama, H., Isobe, T. Trends Biotechnolo 2001; 10, 28-33). Synthesized according to protocol. Briefly, 100 mg polyethylene-L-lysine (average size 17-30 kDa, Sigma, Dorset, UK) in 109 ml mPEG-SPA and biotin PEG-CO-NHS in 1 ml 100 mM sodium carbonate buffer (pH 9). (Shearwater Corporation, Huntsville, AL) was reacted with 1.1 mg for 30 minutes. The reaction was terminated by dialyzing overnight in 1 mM Tris-HCl (pH 7.5). The product from this reaction was called PEG-PLL-biotin (1% PEG derivative contains a biotin head).

Biotinylation of creatine kinase Creatine kinase (100 mg) was dissolved in 1 ml of 1 mM Tris HCl (pH 7.5), and 1 mg of EZ link biotin PEO amine and 1 mg of ethylenediaminecarbodiimide were reacted at room temperature for 20 minutes.

Preparation of affinity capture surface The protein microarray probe was thoroughly cleaned and dried under nitrogen prior to use in the next washing step in acetone, acetonitrile, double distilled water. The newly prepared affinity capture polymer, PEG-PLL-biotin, is then pipetted onto the probe surface and then coated with Nesco film (Azwell Inc., Osaka, Japan). By uniformly dispersing on the surface. After 30 minutes, the probe was washed in 1 mM Tris-HCl (pH 7.5), dried under nitrogen, and then coated with 0.5 mg / ml neutravidin for 1 hour at room temperature in a wet chamber. The probe was then rinsed with wash buffer, washed twice with desalting buffer, and dried under nitrogen. At this time, the surface was ready for use as an affinity capture device very specific for the biotinylated polymer.

Capture and Detection of Biotinylated Protein on Probe Surface The PLL-PEG-biotin neutravidin surface on the MALDI target was overcoated with 5 ng of biotinylated creatine kinase (Roche, Mannheim, Germany). The biotinylated protein is captured on the MALDI target for 2 hours in a wet chamber to prevent drying, washed twice with washing buffer, followed by washing twice with desalting buffer, and the surface under nitrogen. Dried and overcoated with 300 nl of a saturated solution of cyano-4-hydroxycinnamic acid in acetone.

Monitoring Kinase Activity of Immobilized Creatine Kinase on Protein Array The array with immobilized creatine kinase is washed with 100 ml of 1 mM Tris-HCl (pH 7.5) and then 1 mM creatine phosphate, 1 mM ADP, 1 mM MgCl ₂ , and 25 mM Overcoat with a mixture of ammonium bicarbonate buffer in a volume of less than 1 microliter. The enzyme and substrate were incubated for 30 minutes at 37 ° C. in a wet chamber. Reactions omitting either ADP, creatine phosphate, or kinase were performed in parallel with the specificity control.

Results FIG. 3 shows the detection of ADP and ATP. ATP was enzymatically synthesized from the reaction of ADP, creatine phosphate, and creatine kinase in 25 mM ammonium bicarbonate at pH 7.4. [ADP] ⁻ was detected at 427.6 daltons and [ADP + Na] ⁻ was detected at 449.6 daltons. The products of the creatine kinase reaction were detected at 507.6, 529.6, 551.6, and 573.8, and [ATP] ^{− and} three ATP sodium adducts [ATPNa], [ATPNa ₂ ] ⁻ , And [ATPNa ₃ ] ⁻ agreed well with the predicted molecular weight.

Control reactions omitting any one of ADP or creatine phosphate substrate or creatine phosphate kinase enzyme showed no ATP peak.

This is a list of substrates available from Upstate.
http://www.upstate.com/features/kinaseprofiler.q./KinaseProflier+%23153%B#Kinase

Various aspects of the invention are described herein by way of example only with reference to the following drawings and examples.
FIG. 1 shows the oriented binding of the enzyme to the probe. FIG. 2 shows the detection of ADP and ATP by mass spectrometry. FIG. 3 also shows ATP synthesis on the surface mediated by creatine phosphate.

Claims (36)

  i) providing a probe carrying an immobilized enzyme; ii) optionally introducing a test compound; iii) the immobilized enzyme in a time and form sufficient to cause one or more reactants to occur. Iv) drying the probe, v) subjecting the probe to mass spectrometry, and vi) the presence and / or absence of one or more products and / or one or more of the reactants. Determining the activity of the enzyme or the effect of the test compound on the activity of the enzyme, comprising the step of determining the activity of the enzyme or the effect of the test compound on the activity of the enzyme by detecting the presence, Method to determine by using analysis.   The method according to claim 1, wherein the mass spectrometry is laser desorption ionization mass spectrometry, preferably MALDI mass spectrometry.   The method according to claim 1 or 2, wherein the enzyme is a kinase, oxidoreductase, transferase, hydrolase, lyase, or ligase.   2. The enzyme is a protein kinase, protease, carboxylase, esterase, phosphodiesterase, protein phosphatase, G-protein coupled receptor, ATP-dependent chaperone, cyclooxygenase, cytochrome P450, sialidase, short chain dehydrogenase, or short chain reductase. Or the method of 2.   The method according to claim 4, wherein the enzyme is serine kinase, threonine kinase, tyrosine kinase, serine protease, cysteine protease, aspartyl protease, metalloproteinase, or tyrosine phosphatase.   Step ii) is essential and the effect of the test compound on the activity of the enzyme is determined by comparison with the results obtained in the absence of the test compound. The method described in 1.   7. The method of claim 6, comprising adding the test compound before, after or with the one or more reactants to determine the effect of the test compound on enzyme activity. Method.   The method according to any one of claims 1 to 7, wherein the method is qualitative.   The method according to any one of claims 1 to 7, wherein the method is quantitative.   i) providing a probe bearing an immobilized kinase; ii) optionally introducing a test compound; iii) said immobilized kinase in a time and form sufficient to cause one or more reactants to occur. Iv) drying the probe, v) subjecting the probe to mass spectrometry, and vi) the presence and / or absence of one or more products and / or one or more of the reactants. Determining the activity of the kinase or the effect of the test compound on the activity of the kinase by detecting the presence, the activity of the kinase or the effect of the test compound on the activity of the kinase comprising: Method to determine by using analysis.   The method according to claim 10, wherein the mass spectrometry is laser desorption ionization mass spectrometry, preferably MALDI mass spectrometry.   12. The method of any one of claims 3-11, wherein the one or more reactants comprise a phosphate donor, a phosphate acceptor, and a divalent cation.   13. The method of claim 12, wherein the phosphate donor is a phosphorylated substrate and the phosphate acceptor is a nucleotide diphosphate (NDP).   13. The method of claim 12, wherein the phosphate donor is a nucleotide triphosphate (NTP) and the phosphate acceptor is a substrate that is phosphorylated.   The method according to claim 12, wherein the divalent cation is magnesium or manganese.   The method according to claim 13 or 14, wherein the nucleotide diphosphate or triphosphate is adenine diphosphate or triphosphate (ADP or ATP).   17. A method according to any one of claims 1 to 16, wherein the product is a nucleotide triphosphate or a nucleotide diphosphate, the presence of which is detected. Said nucleotide triphosphates or nucleotide diphosphate [NTP] ^- or [NDP] ^- or one or more is detected as a peak of their addition products The method of claim 17. The method of claim 18, wherein the one or more adduct product peaks are adduct product peaks having a monovalent cation (M ⁺ ). The peak of the one or more addition products is [ATPM] ⁻ , [ATPM ₂ ] ⁻ , and [ATPM ₃ ] ⁻ and / or [ADPM] ⁻ , [ADPM ₂ ] ⁻ , and [ADPM ₃ ] ⁻ . 20. The method of claim 19, comprising.   21. A method according to any one of claims 1 to 20, further comprising the step of overcoating the probe with energy absorbing molecules during steps iv) and v).   22. The method of any one of claims 1-21, wherein the one or more reactants and, if present, the test compound are introduced into the immobilized enzyme in compartmentalized form.   23. The method of claim 22, wherein the compartmentalized form is as a droplet.   24. The method of claim 23, wherein the droplet has a volume of less than 1 microliter.   25. The method of any one of claims 1-24, wherein the one or more reactants are provided in a low salt buffer.   26. The method of claim 25, wherein the low salt buffer is an ammonium bicarbonate buffer.   27. The method of any one of claims 1-26, wherein the assay is performed in a humid environment.   28. A method according to any one of the preceding claims, wherein the one or more reactants and optionally any energy absorbing molecules are applied to the probe in the area of use of the immobilized enzyme.   A probe for use in a mass spectrometer, comprising a support having an electrically conductive target surface, the target surface comprising an array having a plurality of enzymes immobilized thereon.   30. The probe of claim 29, wherein the enzyme is a kinase, oxidoreductase, transferase, hydrolase, lyase, or ligase.   30. The enzyme is a protein kinase, protease, carboxylase, esterase, phosphodiesterase, protein phosphatase, G-protein coupled receptor, ATP-dependent chaperone, cyclooxygenase, cytochrome P450, sialidase, short chain dehydrogenase, or short chain reductase. Or the probe according to 30.   The probe according to claim 31, wherein the enzyme is serine kinase, threonine kinase, tyrosine kinase, serine protease, cysteine protease, aspartyl protease, metalloproteinase, or tyrosine phosphatase.   The probe according to any one of claims 29 to 32, wherein the array is a microarray.   The probe according to any one of claims 29 to 33, wherein the enzyme is a fusion protein.   The probe according to any one of claims 29 to 34, wherein the enzyme is immobilized via a label.   36. The probe of claim 35, wherein the label is otine or ble protein.

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