JP5641466B2 - Method for producing peptide - Google Patents

Description

The present invention relates to a method for efficiently producing peptides from animal or plant materials containing proteins, such as industrial byproducts.

It is already known to hydrolyze proteins to obtain amino acids or peptides used as seasonings, pharmaceuticals, cosmetics, beverages and the like. As methods for producing amino acids and peptides from animal and plant materials containing proteins, enzymatic decomposition methods and acid or alkali hydrolysis methods have generally been used. However, in these methods, there is a problem that hydrolysis takes a long time, and hydrolysis under high temperature and high pressure has a problem that amino acids and peptides unstable to heat and acid are further decomposed (for example, patent documents). 1).

Since supercritical water has high reactivity, proposals have been made to produce amino acids and peptides by hydrolyzing proteins using this reactivity (see Patent Document 2). In this method, the protein is degraded at a high speed, but the degradation rate is large, the reaction control is difficult, and it is difficult to recover any components. Also, supercritical water is highly corrosive and the solubility of inorganic salts is reduced, so that salting out occurs and there is a problem of clogging of the tube.

On the other hand, a remarkable chemical reaction promotion effect by microwaves has been recognized, and in organic synthesis, etc., compared with the conventional reaction by external heating, the reaction conditions are moderated, the reaction speed is significantly increased, the reaction selectivity is improved, etc. Has been demonstrated. Therefore, a method for efficiently producing useful amino acids by rapidly hydrolyzing proteins under mild conditions as compared with conventional methods using this microwave has also been proposed (Patent Document 3). In Patent Document 3, the protein is hydrolyzed to amino acids in a short time by a microwave hydrothermal method at a low temperature and low pressure of 150 to 200 ° C. compared to a normal hydrothermal method (under saturated water vapor pressure of 200 ° C. or higher). It has been reported that under alkaline conditions, an amino acid mixed solution reflecting the amino acid composition of the raw protein was obtained by hydrolysis in a short time under a saturated water vapor pressure of 100 to 110 ° C.

However, Patent Document 3 discloses that the hydrolysis rate of the protein is 100% and that a single amino acid mixture is obtained, and nothing is mentioned regarding peptide production by controlling the hydrolysis rate. In addition, although there is a description regarding the combined use of alkali, the ratio of the number of moles of alkali to the number of moles of amide bonds in the protein is not controlled, and the alkali mole excess ratio relative to the protein amide bonds is considerably large. Only the conditions for the protein to degrade to amino acids are described.

By the way, when a protein is hydrolyzed, it is eventually decomposed into amino acids via peptides, but as amino acids absorbed into the living body, the route absorbed as a single amino acid and amino acids are in the form of 2 to 6 mer. It is said that there are two routes that are absorbed by the peptide body. In addition, it is said that only one molecule per molecule is allowed to be absorbed into the human body. From the viewpoint of obtaining dissolved amino acids in living blood, there is one amino acid molecule in the route absorbed as amino acids. On the other hand, since one molecule of peptide, that is, 2 to 6-mer amino acid in terms of amino acid enters the blood, the peptide is several times higher in the blood amino acid concentration measurement result after food acquisition. It has been proven that amino acids are absorbed into it.

On the other hand, when the undegraded protein is added as it is, it takes time to hydrolyze it into a peptide or amino acid by the action of the proteolytic enzyme in the living body and absorbs it. In terms of meaning, pre-hydrolyzing protein components and adding them to food, feed, etc. has a great meaning in terms of time efficiency. In particular, the method of absorbing in the form of a peptide as described above is more efficient than adding it in the form of an amino acid. Therefore, development of a technique for selectively producing a peptide, that is, efficiently obtaining a peptide by controlling the molecular weight is strongly desired.

JP 2002-332265 A Japanese Patent Laid-Open No. 2002-60376 JP 2004-345998 A

As described above, a method for efficiently producing an amino acid mixture from a protein using microwaves is known, but a method and conditions for mainly producing a peptide are not known. Therefore, the subject of this invention is providing the method and conditions which hydrolyze a protein and mainly manufactures a peptide efficiently.

The present invention relates to animal and vegetable proteins in alkaline water containing 0.5 to 3 times moles of alkali with respect to the total number of moles of amide bonds of the protein under microwave irradiation. It is a method for producing a peptide, characterized in that it is partially hydrolyzed at a temperature below the boiling temperature and under normal pressure . As the alkali, sodium hydroxide or potassium hydroxide is preferably used. Furthermore, a preferable condition is a method using 1 to 2 moles of alkali with respect to the total number of moles of amide bonds of the protein. Although the boiling temperature of the alkaline water depends on the concentration of the alkaline water, it is about 105 ° C. at the maximum, and the treatment time is suitably 40 minutes or less, preferably 20 minutes or less at a temperature below the boiling temperature. And it is preferable to hydrolyze partially in the range whose protein hydrolysis rate is 40%-80%.

According to the present invention, by using microwave irradiation in combination, the protein can be obtained by hydrolysis in a range where the number of moles of alkali relative to the total number of moles of amide bonds of animal and vegetable proteins is relatively small and under boiling conditions. The peptide can be continuously produced while hydrolyzing in a shorter time than the conventional method and suppressing the production of amino acids. The resulting peptide can be purified by removing excess alkali with an ion exchange resin, and if necessary, can be recovered as a solid by using a known drying method, and can be used as an additive to animal feeds. It can also be used as an additive to foods and cosmetics. In the present invention, the protein is treated at a high temperature below the boiling temperature in the presence of an alkali so that the antibody and the like can be completely treated, and the product is purified in the form of a carboxylic acid neutral salt. A readily soluble peptide is provided.

FIG. 3 is a view showing amino acid analysis results of the product in Example 1 by gas chromatography. It is a figure which shows the comparison of the conventional method and this invention (microwave method) (result by TOF-MS). It is a figure which shows the maximum molecular weight and average molecular weight of the product in Example 3 (result by TOF-MS). It is a figure which shows the GPC analysis result with respect to the decomposition rate on the conditions employ | adopted in Example 4. FIG. It is a figure which shows the GPC analysis result with respect to the decomposition rate on the conditions employ | adopted in Example 5. FIG. It is a figure which shows the GPC analysis result with respect to the decomposition rate on the conditions employ | adopted in Example 6. FIG. It is a figure which shows the GPC analysis result with respect to the decomposition rate on the conditions employ | adopted in Example 7. FIG.

The present invention relates to animal and vegetable proteins in alkaline water containing 0.5 to 3 times moles of alkali with respect to the total number of moles of amide bonds of the protein under microwave irradiation. In this method, a peptide is obtained by partial hydrolysis at a temperature below the boiling temperature. The animal and plant protein used in the present invention means an animal and plant protein contained in natural animal and plant materials, an animal and plant protein contained in agricultural and fishery processing waste, food waste, etc., and is not particularly limited. Absent. In carrying out the present invention, even if the material containing the protein is used for hydrolysis as it is, the material containing the protein is pretreated by an appropriate method and purified to a material mainly composed of protein. May be.

The invention of Patent Document 3 employs microwaves and alkalis for protein hydrolysis, and temperature conditions are similar to those of the present invention. However, in Patent Document 3, the amount of alkali used for the amide bond in the protein is very large, which is a condition for obtaining an amino acid rather than a peptide, and is different from the method of the present invention. Specifically, the amount of alkali used from Example 2 of Patent Document 3 will be calculated. Although silk fibroin 20 mg is used, but the nitrogen content of silk fibroin is unknown, even if all 20 mg is calculated as nitrogen, the number of moles of amide bond is (20/1000) /14=0.00143 mol. Yes (actually less). Since 20 ml of 1N to 6N is added to the alkali, 1/1000 × 20 to 6/1000 × 20 = 0.02 to 0.12 mol. Therefore, the alkali / amide molar ratio = 14 to 84 times mol (actually larger), which is greatly different from the alkali / amide molar ratio in the present invention being 0.5 to 3 times. In the present invention, although the degradation rate is increased when microwaves are used, in order to selectively obtain peptides, it is necessary to control the molar ratio of alkali to amide bond, and furthermore, the degradation rate can be controlled by controlling the treatment time. It has been completed by knowing that the maximum peptide can be obtained by controlling.

Microwaves are electromagnetic waves having a wavelength of 100 μm to 1 m, and when irradiated to a liquid, the temperature can be increased efficiently compared to heating with a heater or the like. A microwave oven is widely known as an appliance using microwave heating, but as a microwave irradiation device (2.45 GHz), various types of batch systems are known, and a continuous processing type is also available. Microwave chemical reactors are also known. In the present invention, any known device may be used.

In the hydrolysis of the present invention, it is necessary to suppress the hydrolysis of the protein until it reaches the amino acid (100%) without being decomposed. Therefore, the hydrolysis is performed at a relatively low temperature using a relatively low concentration of alkali. As the alkali, sodium hydroxide or potassium hydroxide is preferable, and 0.5 to 3 times mol, preferably 1 to 2 times mol of alkaline water is added to the number of moles of the amide conjugate of the protein. The hydrolysis is carried out at a temperature not higher than the boiling temperature depending on the alkaline water and not higher than 105 ° C.

It is preferable that the hydrolysis is carried out at this temperature for 40 minutes or less, preferably 20 minutes or less, and under a condition of a hydrolysis rate of 40 to 80%. If hydrolysis is performed under such conditions, the production of amino acids can be suppressed, and animal and plant proteins can be degraded in a short time to produce peptides as the main components. If a continuous processing type microwave chemical reaction apparatus is used, peptides can be produced continuously. The produced peptide usually contains substances other than the target peptide, so that it can be purified by, for example, an ion exchange resin or a synthetic adsorbent and used as an additive to animal feeds, foods, cosmetics, etc. Can be used.

When the amount of the alkali added is less than 0.5 times the number of moles of the amide bond of the protein, it reacts with the carboxylic acid produced to produce a salt, so that the decomposition of the protein does not progress so much, and the high molecular protein component Or remains in a polypeptide-rich form, and the absorption efficiency into the living body is not good. If the amount exceeds 3 times the number of moles of the amide bond of the protein, the hydrolysis of the protein proceeds with excess alkali, but the degradation rate increases with treatment time (in minutes) as the excess rate increases. The inclination is large and it is not easy to stop halfway. For peptide acquisition, there is an optimum alkali addition ratio with respect to the total number of moles of amide bonds in the protein, the optimum range is 0.5 to 3 times the mole, and the optimum range is related to the excess alkali treatment load. To 1 to 2 moles. On the other hand, when the amount of alkali added is more than 3.0 times the molar amount, it is not preferable for the purpose of obtaining the oligopeptide at the optimum concentration because the decomposition easily proceeds to the amino acid through the oligopeptide. For the purpose of obtaining amino acids, it is advantageous to increase the alkali excess, but the object of the present invention is to obtain an effective oligopeptide content by controlling the alkali excess and controlling the treatment time. .

As the hydrolysis temperature, if it is too low, there is a disadvantage that the hydrolysis time becomes long, but it is not particularly limited. When the microwave is used as the upper limit temperature, the boiling point varies depending on the alkali concentration under normal pressure, but the maximum temperature does not increase to 105 ° C. or higher without pressure. Use at normal pressure is preferred, but the pressure is not particularly limited, and the upper limit is the boiling temperature of the added aqueous alkali solution.

If the water decomposition rate of a protein is 100%, all amino acids are used, 0% is the protein itself, 80% or more contains many amino acids, 40% or less is undegraded protein, and the degree of polymerization as a peptide. A large polypeptide is not preferred because it increases. In the case of the same alkali excess rate under normal pressure, when not using microwaves, it takes several tens of hours or more to secure the same decomposition rate even if the same thermal decomposition is performed at the boiling temperature (several tens times) Therefore, the effect of using microwaves and appropriate alkali excess conditions is great. In general, the method for obtaining a peptide by an enzymatic method, which has been established as a production method, has a significant difference from the method of the present invention because the degradation rate is orders of magnitude slower and usually takes several days. In addition, for example, raw soybeans have proteolytic enzyme inhibitors and have not been widely used, but it is known that they will disappear if heated. Although it is necessary to perform the heat treatment at such a stage, the microwave heat treatment method using alkali as in the present invention is not necessary, and there is an advantage that the decomposing enzyme inhibitor is also decomposed.

As in the present invention, when an animal or vegetable protein is hydrolyzed under microwave irradiation, in addition to the effect that the hydrolysis time is shortened, the effect that a uniform hydrolysis reaction becomes possible is also obtained. That is, when the hydrolysis reaction is carried out without using microwaves, there are a portion where the animal and plant protein is easily cut and a portion where it is difficult to cut, so that the generated peptide fragments tend to be unevenly distributed. However, since the hydrolysis reaction proceeds uniformly for all peptide bonds by using microwaves, the degradation can be limited to peptide fragments of a specific length by controlling the hydrolysis time. . Depending on the conditions, it can be hydrolyzed to amino acids, but within the scope of the conditions of the invention it can be retained with a peptide.

The peptide of the present invention means a dipeptide or more oligopeptide or polypeptide in which two or more amino acids are bonded by a peptide bond. A so-called oligopeptide or polypeptide having about 100 or less constituent amino acid residues is preferred. Preference is given to 2-6 mer oligopeptides. Since the high molecular component of protein is once decomposed in vivo by a biodegrading enzyme to become a peptide and an amino acid, it is inefficient in terms of absorption, and it is very useful to use an oligopeptide-type additive. It may be a specific single substance or a mixture of various peptides.

When the peptide obtained in the present invention is used, for example, as a food, the form is not particularly limited, and the peptide of the present invention is prepared as it is as a food or drink, various proteins, sugars, fats, trace amounts What further mix | blended an element, vitamins, etc., what was made into the liquid, semi-liquid form, or the solid form, and what was added to the general food-drinks may be used. In addition, the term “food” is used to mean a wide range of health foods, health supplements, foods for specified health use, and the like. As an animal feed additive, it can be added as a growth promoter or a physical strength enhancer to feed for feeding cultured fish, other feeds for livestock such as chickens, pigs, and cattle.

The amino acid analysis in the present invention was performed by a usual method using gas chromatography.
Specifically, the column was HP-1 (Agilent Technologies) 0.32 mmφ × 30 m, 50 to 350 ° C., and the temperature was raised at 10 ° C./min, and the detection was performed by the FID method. Regarding molecular weight and molecular weight distribution, TOF-MS (Time of Flight Mass Spectrometry) was measured using α-cyano- in a water / acetonitrile / trifluoroacetic acid mixed solution using a Voyager Linear-DE / K analyzer manufactured by Japan Perspective. The measurement was carried out using a 4-hydroxycinnamic acid system as a matrix. Also,
GPC (Gel Permeation
Chromatograph) analysis, specifically, Sephadex G-50 (diameter 2 mm, length 10 cm) as a column, UV-D2 (254 nm) flow rate 2 mL / min as a detector, sample amount 0.3 mL As a marker sample, lipase (MW: 48,000), lysozyme (MW: 14,000), and a soy amino acid mixed solution were used.

The protein hydrolysis rate (%) is a value determined by the following formula.
Hydrolysis rate (%) = (N-terminal amount / total nitrogen amount) × 100
Here, the N-terminal amount is between the inflection point on the alkali side (about pH 11) to the inflection point near pH (about pH 6.5) in the neutralization curve obtained by applying an alkaline peptide solution to an automatic titrator. The amount of hydrogen ions required, i.e., the amino acid and peptide present as anions in an alkaline solution are equal to the amount of hydrogen ions required to become zwitterions, and the total nitrogen amount is the Kjeldahl method The value obtained in (1) was used. The defatted soybean used in Examples and Comparative Examples has a Kjeldahl nitrogen analysis value of 7.68% by weight.

Hereinafter, the present invention will be described in detail by way of examples.

[Example 1]
A constant amount of 10 g of defatted soybean flakes pulverized by a home mixer (amide group equivalent N mole number 0.055 mol) is always taken into a 200 mL flask, and NaOH aqueous solution (always 50 mL constant amount by changing the alkali concentration) ) Was added. The added alkali concentration was changed as follows.

1) Alkaline concentration 0.25N / L, 50ml, Alkaline addition mole number 0.0125mol, Ratio: 0.23 times mole 2) Alkaline concentration 0.5N / L, 50ml, Alkaline addition mole number 0.025mol, Ratio: 0.45 times mole 1N / L, 50ml, alkali addition mole number 0.05mol, ratio: 0.91 times mole 4) alkali concentration 2N / L, 50ml, alkali addition mole number 0.1 mole, ratio: 1.82 times mole 5) alkali concentration 3N / L, 50ml, Alkaline added mole number 0.15 mole, ratio: 2.73 times mole 6) Alkali concentration 4N / L, 50ml, alkali added mole number 0.2 mole, ratio: 3.64 times mole

A flask was placed in a microwave reactor (manufactured by Shikoku Measurement Co., Ltd., 2.45 GHz frequency, 325 kW output constant of maximum 650 W), a reflux tube was set up here, and microwave treatment was performed for 5 minutes while stirring with a magnetic stirrer. . At this time, the internal temperature was controlled to 96 ° C. using a thermocouple thermometer. After completion of the reaction, the contents were taken out and the amount of amino acids in the liquid was measured. Figure 1 shows the results. As can be seen from FIG. 1, when the sodium hydroxide concentration is 4 N / L, alanine, aspartic acid and the like are produced in large quantities, but at 3 N / L or less, only a small amount of alanine is produced. It can also be seen that at 2 N / L or less, amino acids other than lysine are hardly generated. Therefore, when the alkali is 3 N / L or less, particularly 2 N / L or less, it can be presumed that the degradation of the protein is mainly stopped by the peptide.

By the way, when the alkali addition concentration is 1.1 N / L, the addition amount is equimolar with respect to the number of moles of protein amide bond, and the equivalence is also with respect to the carboxylic acid to be produced. It becomes a form. If the amount of addition is larger than that, the alkali becomes an excess condition. However, in order to obtain the peptide efficiently, it is necessary to define the optimum alkali excess molar number and the treatment time.

[Example 2]
5 g of soybean meal (amide group equivalent N mole number 0.0275 mol) using 1 N / L / NaOH aqueous solution (50 ml: 0.05 mol molar ratio: 1.82 times mol) in an oil bath at 100 ° C. FIG. 2 shows the results of analyzing the molecular weight distribution by the TOF-MS method in the case of time treatment (conventional method) and in the case of treatment for 5 minutes with a microwave controlled at 96 ° C. As can be seen from FIG. 2, in the conventional method, 60% or more remains as a protein or polypeptide having a molecular weight of 10,000 or more even after 1 hour treatment, but in the microwave treatment of the present invention, the molecular weight is 10,000 after treatment for 5 minutes. No more remains. Although it depends on the conditions, if microwaves are used, hydrolysis is possible at a speed several tens to several hundreds times faster than the conventional method.

[Example 3]
Hydrolysis was performed by changing the concentration of the NaOH aqueous solution in the same manner as in Example 2, and the obtained hydrolysis product was measured using TOF-MS to obtain the maximum molecular weight and the average molecular weight (weighted average). The results are shown in FIG. As can be seen from FIG. 3, protein (polypeptide having a molecular weight of 10,000 or more) remains when the NaOH concentration is 0.5 mol / L (= N / L: alkali / amide molar ratio = 0.91 times mol). No residue remains above 1 mol / L (= N / L: alkali / amide molar ratio = 1.82 times mol). The average molecular weight is about 250 to 600 when the NaOH concentration is 1 to 3 mol / L (= N / L: alkali / amide molar ratio = 1.82 to 5.5 times mol).

As a result of the analysis of the amino acid obtained in Example 1 (as shown in FIG. 1, 4 mol / L (= N / L: molar ratio = 3.64 times mol), various amino acids are produced in large amounts. Less than L (= N / L: molar ratio = 2.73 times mole) produces almost no lysine, and less than 1 mol / L (= N / L: 0.91 times mole) produces only lysine.) The NaOH concentration is 0.55 to 3.3 mol / L (= N / L: molar ratio = 0.5 to 3 times mol), preferably 1.1 to 2.2 mol / L (= N / L: molar ratio = 1 to 2 moles), it can be said that it is possible to obtain a peptide while suppressing the production of amino acids.

[Examples 4 to 7]
According to Example 1, the same test was performed except that the decomposition time was 15 minutes. A fixed amount of 10 g of defatted soybean flakes (N mole number in terms of amide group 0.055 mol) pulverized by a home mixer is collected, put into a 200 mL flask, charged with the following alkaline conditions, and microwaved (325 W). Decomposed. After 3 to 4 minutes, the boiling point reached 103 ° C. from room temperature, and the remaining temperature up to 15 minutes remained constant at 103 ° C.

1) Alkali concentration 1 N / L, 50 ml, 0.05 mol added alkali, ratio: 0.91 times mol (Example 4)
2) Alkali concentration 1.1 N / L, 50 ml, alkali addition mole number 0.055 mol, ratio: 1 time mol (Example 5)
3) Alkali concentration 2.2N / L, 50ml, alkali added mole number 0.11mol, ratio: 2 times mole (Example 6)
4) Alkaline concentration 3.3 N / L, 50 ml, alkali addition mole number 0.165 mol, ratio: 3 times mol (Example 7)

The results of titration analysis of the decomposition rate of the liquid hydrolyzed under the above conditions and the results of molecular weight distribution analysis using GPC are shown in Table 1 and FIGS. The conditions of GPC were as follows.
Pump: EYELA VSP-3050 (flow rate = 2 mL / min)
Detection: EYELA UV-D2 (wavelength = 254 nm)
Column: Sephadex G-50 (diameter 2 cm, length 10 cm)
Marker: Lipase, lysozyme, amino acid mixed solution (same as soy amino acid composition)
Injection volume: 0.3 mL

[Comparative Example 1]
The hydrolysis time was 15 minutes exactly as in Examples 4-7. A test was conducted with an alkali concentration of 3.3N / L 50ml, with a small amount of defatted soybean flakes added as low as 2.15g to increase the relative excess, but the boiling state was the same. (N mole number in terms of soy flake amide charged: 0.0118 mol) Alkaline concentration: 3.3 N / L, 50 ml Alkaline added mole number: 0.165 mol, ratio: 14 times mol, showing a hydrolysis rate of 100%. In another test, it was confirmed that all amino acids were produced at 100% hydrolysis rate.

[Comparative Example 2]
In accordance with Example 6, however, a comparative test of only heat treatment was conducted without using microwaves. 10g of soy flakes, alkali concentration 2.2N / L, 50ml, alkali added mole number 0.11mol, ratio: 2 times mole, temperature maintained at 103 ° C, but if microwave is not used, 10 times or more took time. The hydrolysis rate at the time of 15 minutes showed a value of 32.3%, and the effect of using the microwave was confirmed as compared with Example 6.

4-7, all the proteins have decomposed | disassembled, a peptide exists between an amino acid component and a protein polymer, and the thing of a peptide main component with few protein polymers and few amino acids is obtained. It can be seen that the hydrolysis rate range is in the range of 40-80%. At that time, the ratio of the number of moles of alkali added to the number of moles of the amide component in the protein is in the range of 0.5 to 3 times, and the preferred range is in the range of 1 to 2 times.

Claims (3)

Animal and vegetable proteins are irradiated with microwaves in an alkaline water containing 0.5 to 3 times moles of alkali with respect to the total number of moles of amide bonds of the protein, and the boiling temperature of the alkaline water is lower than the boiling temperature. A method for producing a peptide, which comprises partially hydrolyzing under temperature and normal pressure . The method for producing a peptide according to claim 1, wherein alkaline water containing 1 to 2 moles of alkali is used with respect to the total number of moles of amide bonds of the protein. The method for producing a peptide according to claim 1 or 2, wherein the protein is partially hydrolyzed within a hydrolysis rate of 40 to 80%.

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