Enzymatic modification of protein

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

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. 

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... 

Cnzyme-catalyzed modifications of proteins deserve much more work and therefore must be considered as an important field for further scientific investigations. In spite of the prolific research carried out in this area during the past three decades, a number of enzymatic modifications not only are poorly investigated or understood but attempts to apply them to food protein systems are nonexistent. The fundamental aspects of enzymatic modification of proteins are of interest since potential applications for nutritional and functional improvements of food proteins appear to be numerous and promising. Enzymatic and chemical modifi-... 

These nonhydrolytic, post-translational enzymatic modifications of proteins, described in two recent publications (9,10), will not be treated further in this chapter. Hydrolytic modification, in vivo and in vitro, is the single most frequently occurring enzymatic modification of proteins. 

In Vitro Enzymatic Modification of Proteins Through Hydrolysis... 

Enzymatic Modification of Proteins for Food Use. Proteolytic enzymes are used extensively for modifying proteins in various ways in food products and for waste management (17, 27. These are used in baked and brewed products, cereals, cheese, chocolate/cocoa, egg and egg products, feeds, fish, legumes, meats, milk, protein hydrolysates and wines. But there are many other uses, and potential uses, of enzymes to modify protein. Whitaker (27, 28), and Whitaker and Puigserver (29) have described more than 100 enzymatic modifications of proteins in vivo, challenging scientists to look at the possibilities of modifying the amino acid side chains by proteolytic and other methods. 

Casey, P.J., Thissen, J.A., and Moomaw, J.F. (1991). Enzymatic modification of proteins with a geranylgeranyl isoprenoid. Proc Natl Acad Sci USA 88 8631-8635. 

Glycosylation is the most frequent enzymatic modification of proteins. Many integral membrane proteins have oligosaccharides covalently attached to the extracellular region,... 

Application of membrane processes during production of purified food proteins is a mild treatment which ensures that the functional properties of the native proteins are retained. (1 ) These properties are mostly found to be superior to those of denatured proteins. However, not all possible needs of the modern food industry are fulfilled by using native proteins instead of denatured ones. Therefore, enzymatic modification of proteins has been demonstrated as a possible means of meeting the needs of the food industry for high-quality protein ingredients ( ), (13), (14). 

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. 

Table I. Application of Membrane Processes During Enzymatic Modification of Proteins...

Molecular processing the evaluation of the progression and outcome of enzyme assays, such as aggregation, polymerization, degradation, or enzymatic modification of proteins or nucleic acids ... 

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