Enzymatic hydrolysis of proteins

Protein hydrolysates are usually produced by limited enzymatic hydrolysis of protein molecules in foodstuff, yielding polypeptides that are smaller in molecular mass. Protein hydrolysis has several aims. The most common is to make the protein moiety of afoodstuff soluble by reducing the size of the peptides. Solubilization simplifies isolation of the protein moiety by physical means. Protein hydrolysis has also been applied to improve the functional, organoleptic, and nutritional value of a foodstuff. Advances in the technology of protein hydrolysate production has allowed the use of unconventional protein sources for animal and human food. 

Perform enzymatic hydrolysis of protein samples at a series of time points (see Basic Protocol 1, steps 1 to 5). Prepare a series of standards and a blank (see Basic Protocol... 

Adler-Nissen, J. 1976. Enzymatic hydrolysis of proteins for increased solubility. J. Agric. Food Chem. 24 1090-1093. 

Medina and Phillips (36) analyzed the peptide pattern obtained by the enzymatic hydrolysis of proteins isolated from beef, pork, chicken, and soybean sequentially, using TLC and HPLC to identify the proteins. The analysis was performed using RP-HPLC on a /zBondapak C8 column under isocratic conditions using triethylamine phosphate buffer (0.0833 M, pH 3) as solvent. Figure 5 depicts the peptide pattern of fraction IV isolated from beef, soybean, chicken, and pork by TLC. Identification of the different foods was accomplished by applying discriminant analysis to the peptide pattern. 

Total thiamine Milk Enzymatic hydrolysis of protein with trypsin and thiamine phosphates to thiamine with claradiastase oxidation of thiamine to thiochrome using ferricyanide (derivatization stopped with sodium sulphite) thiochrome extracted with 1-butanol Analytical Nucleosil Phenyl (150 mm, 5 fi Macherey-Nagel). Isocratic methanol + acetonitrile + isobutanol + water (80 +10+10+5 v/v/v/v). 0.7 ml/min. Fluorescence 375/430 nm (ex/em). External standardization. 76 Recoveries 95% thiamine as thiochrome from milk. 

Murakami, Y. and Hirata, A. 2000. Novel process for enzymatic hydrolysis of proteins in an aqueous two-phase system for the production of peptide mixture. Prep. Biochem. Biotechnol. 30, 31-37. 

Enzymatic hydrolysis of proteins in vivo is a very important process and it is used biologically in many ways (see Table VI). Generally these reactions can be grouped as either important for protein turnover or for... 

Mukhin, V. A., and Novikov, V. Y. 2001. Enzymatic hydrolysis of proteins from crustaceans of the Barents sea. Appl. Biochem. Microbiol., 37, 538-542. 

Factors which affect the rate and extent of enzymatic hydrolysis of proteins include (1) the substrate specificity of the enzymes, (2) modification of the amino acid side chains of the substrate proteins, and (3) the three-dimensional structure of the substrate proteins. It is essential that the active center of the enzymes be able to bind with specific amino acid residues of the substrate protein. The native soybean protein molecules are completely folded and therefore the specific amino acid residues required by the enzymes may not be available. This is why native... 

The hydrolysis of proteins by chemical and enzymatic methods is discussed by R. L. Hill in the second chapter. The chapter should serve as a standard source for information on the many operational techniques with which only the experienced specialist is likely to be familiar. Dr. Hill covers not only the partial hydrolysis of proteins by general and specific procedures but also tbe total enzymatic hydrolysis of proteins for the purpose of amino acid analysis. 

Membrane processes have a potential application within many areas of industrial enzymatic hydrolysis of proteins. Table 1 shows how membrane processes can be applied in the different types of enzymatic modification of protein. Thus membrane processes may be used for pre-treatment of proteins, for the reaction step and as an essential part of the purification or posttreatment step. 

Enzymatic hydrolysis of proteins results in changing the molecular mass of the molecules. However, the effects of protein size on the hydrophobic behavior of amino acids are of great importance [132]. There is a meaningful relationship between hydrophobicity (which may affect the surface of the molecule) and functionality of food proteins [11,133] proposed using the term relative surface hydrophobicity. The proteolysis should be carefully limited for improving the functional properties of food proteins [147]. Mild hydrolysis improves functionality of proteins, while extensive hydrolysis depresses it [139,148],... 

Enzymatic hydrolysis of proteins results in the production of amino acids ... 

We have described an approach to host plant resistance that involves the use of plant oxidative enzymes to irrevocably deprive the insect of nutrients. We have emphasized that the chemical reactions catalyzed by POD and PPO have the potential to destroy a variety of essential or limiting amino acids (Table X). In particular, these reactions are adept at destroying lysine and cysteine. Integral lysine is necessary for proper enzymatic hydrolysis of protein. Cysteine and methionine, amongst other uses, are required to synthesize trjrpsin. The action of PPO and POD in conjunction with Pi s are proposed to place a severe strain on the insect for high sulphur amino acid intake. This strain may be further exacerbated by the complementary action of quinones... 

Figure 19 Schematic relationship between enzyme specificity, average hydrophobicity, and peptide chain length in enzymatic hydrolysis of proteins.

Then a solution of papain (200ml of 0.1% solution of papain per 1kg of material) is added. Enzymatic hydrolysis of proteins is carried out for 20-40h. Every 6-8 h the pH must be adjusted to 6-7 (to optimize enzyme activity). The HA mixture is purified by ultrafiltration and precipitation with 96% ethanol. The final product, sodium hyaluronate, is dried by lyophilization and the precipitate is then dissolved in a water-alcohol mixture containing 40% ethanol. The final purification of hyaluronan is performed by membrane filtration of a solution containing 30-50% ethanol. 

Many food products (including soy sauce and other oriental sauces) that are produced by enzymatic hydrolysis of proteins... 

Especially in the fields of amino acids and peptides, such as they are obtained by enzymatic hydrolysis of proteins, a two-dimensional combination of paper or thin-layer chromatography and electrophoresis has become very popular. The patterns of tryptic hydrolysates are termed hnger-prints and can reveal abnormal peptides if mutated anomalous proteins are compared with their normal counterparts. Similar finger-prints can be obtained from nucleic acid digests. 

The synthesis of peptides by enzymatic hydrolysis of proteins was carried out with gas-vortex gradientless bioreactor of type BIOK-022. As enzymes were used pepsin and trypsin. Initial concentration of the protein substrates was 20% on weight. Temperature of the synthesis was 36-40 C. Synthesis was carried out during 1 h. Received peptides molecular weight was 800-1100 g/mol of titration method with formalin [2],... 

Enzymatic hydrolysis of proteins is an attractive alternative to the hydrolytic procedures and has been used to avoid destruction of tryptophan (174). A mixture of proteolytic enzymes, such as chymo-trypsin, thermolysin, papain, leucine aminopeptidase and pronase has been used (135, 192, 353). Upon completion of the enzymatic hydrolysis of the protein, the hydrolyzate is rendered free of proteolytic enzymes by precipitation and centrifugation and the extract directly analyzed with the amino acid analyzer. The method however may not be generally valid, because of the possibility of artefacts due to self-digestion of the enzymes used. 

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