Protein enzymatic modifications

The earliest commercial milk protein enzymatic modification dates back to the 1940s, when the first formulas for allergenic infants were made. The aims of this process were to reduce allergenicity as well as to change the functional properties of proteins while preserving their nutritional value for clinical use. Unfortunately the hydrolysates thus obtained were characterized by bitter taste, and for mainly this reason proteolysis, as a technological process, enjoyed very little popularity. 

D. Similar methods were used for modification of the enzymes listed in Table II as well as bovine hemoglobin (see Table III). The choice of conditions for the modification reactions (pH, temperature, etc.) was made mainly based on the properties/stability of each protein. Enzymatic activities were measured by previously reported methods (77,27-25). 

Soya Proteins. Early attempts to make albumen substitutes from soya protein also ran into problems. A bean flavour tended to appear in the finished product. A solution to these problems has been found. Whipping agents based on enzyme modified soy proteins are now available. The advantage of enzymatic modification is that by appropriate choice of enzymes the protein can be modified in a very controlled way. Chemical treatment would be far less specific. In making these materials the manufacturer has control of the substrate and the enzyme, allowing the final product to be almost made to order. The substrates used are oil-free soy flakes or flour or soy protein concentrate or isolate. The enzymes to use are chosen from a combination of pepsin, papain, ficin, trypsin or bacterial proteases. The substrate will be treated with one or more enzymes under carefully controlled conditions. The finished product is then spray dried. 

Mode of action Activation of macrophages/monocytes release of endogenous mediators such as lipids from arachidonic acid, reduced oxygen species, proteins 1. Pore formation in cell membranes 2. Enzymatic modification of specific substrates in the cytosol of host cells (AB-type toxins) 3. Superantigen stimulation of the immune system... 

In addition to the 20 proteinogenic amino acids (see p. 60), there are also many more compounds of the same type in nature. These arise during metabolic reactions (A) or as a result of enzymatic modifications of amino acid residues in peptides or proteins (B). The biogenic amines (C) are synthesized from a-amino acids by decarboxylation. 

Effective Hamaker constant, 234 Emulsifying activity index, 186,188/ Emulsions, concentrated oil-in-water, effea of interdroplet forces on centrifugal stability, 229-245 Enhancers of taste. See Taste enhancers Enzymatic modification of soy proteins, 181-190... 

Deeslie, W. D. and Cheryan, M. (1981). Continuous enzymatic modification of proteins in an ultrafiltration reactor. ]. Food Sci. 46,1035-1042. 

Panyam, D., Kilara, A. (1996). Enhancing the functionality of food proteins by enzymatic modification. Trends in Food Science and Technology, 7, 120-125. 

It is essential to consider the physico-chemical properties of each WPC and casein product in order to effectively evaluate their emulsification properties. Otherwise, results merely indicate the previous processing conditions rather than the inherent functional properties for these various products. Those processing treatments that promote protein denaturatlon, protein-protein Interaction via disulfide interchange, enzymatic modification and other basic alterations in the physico-chemical properties of the proteins will often result in protein products with unsatisfactory emulsification properties, since they would lack the ability to unfold at the emulsion interface and thus would be unable to function. It is recommended that those factors normally considered for production of protein products to be used in foam formation and foam stabilization be considered also, since both phenomena possess similar physico-chemical and functionality requirements (30,31). 

Another method of protein treatment involves enzymatic modification. Enzymes per se may be added or the protein may be subjected to the microbial enzymes produced from fermentation. There is little evidence to indicate that the amino acid availability is influenced by these treatments, although one might expect benefits from increased... 

Enzymatic modification of proteins applicable to foods is reviewed by Whitaker ( ). Described briefly are present uses of proteolytic enzymes for modifying proteins through partial hydrolysis. Major emphasis is placed on those enzymes which bring about aggregation of proteins, cross-link formation, and side chain modification through post-translational changes in the polypeptide chain. 

Houseman, B. T. and Mrksich, M. (2002) Carbohydrate arrays for the evaluation of protein binding and enzymatic modification. Chem. Biol. 9(4), 443-454. 

The above discussions have shown how selected analytical techniques can be applied to vastly different proteins to solve a myriad of problems. These include routine assays amino acid and sequencing analyses specialized techniques FAB-MS and IEF conventional techniques refined to improve their utility reversed-phase HPLC using different pHs, organic modifiers, and temperatures and chemical and enzymatic modifications. The latter two procedures have been shown to be effective not only in elucidating primary structure but also in probing the conformation of proteins. 

Feeney, R.E., Whitaker, J.R. (eds) 1977. In Food Proteins Improvement Through Chemical and Enzymatic Modification , Advances in Chemistry Series 160. American Chemical Society, Washington, DC. 

The chemical and enzymatic modification of proteins should continue to be an expanding and perhaps even burgeoning subject. New applications and cross-fertilization of the more established ones are evident today. Two examples of how efforts in the areas of food, nutritional, and pharmaceutical sciences have much in common will be cited here. 

Fundamentals and Applications of Enzymatic Modifications of Proteins An Overview... 

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