Protein deteriorated

Photooxidations are not normally considered a protein deteriorative reaction because they usually go unseen or are found only when purposely contrived, such as in the chemical modification of proteins (Figure 17). However, the possibility of their occurrence in foods, particularly those containing added dyes, should not be overlooked. Several of the important amino acid side chains are readily modified, including the sulfhydryl, imidazole, phenoxy, indole, and th1o ether (Figure 18). More general and detailed coverage 1s provided in another article in this volume (34). 

There are many possible conclusions to draw from an examination and summarization of what is known about protein deteriorations. Two main conclusions are ... 

Some Particular Areas for Future Investigations on Protein Deteriorations... 

The subject of protein deteriorations encompasses most of protein chemistry and is a wide-ranging and difficult topic. It is hoped that from this article and the other articles in this... 

The following are some possible areas for future investigations of protein deteriorations ... 

This review focuses upon the post-translational modification and chemical changes that occur in elastin. Outlined are the steps currently recognized as important in the assembly of pro-fibrillar elastin subunits into mature fibers. Descriptions of some of the proposed mechanisms that appear important to the process are also presented. It will be emphasized that from the standpoint of protein deterioration, elastin is a very novel protein. Under normal circumstances, the final product of elastin metabolism, the elastin fiber does not undergo degradation that is easily measured. Unlike the metabolism of many other proteins, deterioration or degradation is most evident biochemically in the initial stages of synthesis rather than as a consequence of maturation. Since the presence of crosslinks is an essential component of mature elastin, a section of this review also addresses important features of crosslink formation. 

Proteins in human nutrition—Congresses. 2. Proteins—Deterioration—Congresses. 

Eennema, O. 1982. Behavior of proteins at low temperatures. In Food Protein Deterioration Mechanisms and Functionality (Cherry, J.P., ed.), p. 109. ACS Symposium Washington, DC. 

J. E. Kinsella. in Food Protein Deterioration, Mechanisms and Func-... 

Freidman, M. Lysinoalanine formation. Soy Proteins Kinetics and Mechanism, in Food Protein Deterioration Mechanisms and Functionality ACS Symposium Series 1982, 206, 231—273. 

J. A. B. Baptista and R. C. B. Carvalho, Indirect determination of Amadori compounds in milk-based products by HPLC/ELSD/UV as an index of protein deterioration. Food Res. Int, 37 (2004) 739-747. 

Friedman, M. (1982). Lysinoalanine formation in soybean proteins kinetics and mechanisms. In "Mechanism of Food Protein Deterioration", J.P. Cherry Ed., American Chemical Society Symposium Series, Washington, D.C., 206, 231-272. 

Friedman, M., Grosjean, O.K. and Zahnley, J.C. (1982c). Effect of disulfide bond modification on the structure and activities of enzyme inhibitors. "Mechanisms of Food Protein Deterioration", J.P. Cherry, Ed., ACS Symp. Series,... 

Two non-inhibitory proteinase—proteinase inhibitor combinations exhibit destabilization of inhibitor proteins in the DSC (Zahnley, unpublished). Ovoinhibitor was rapidly degraded by thermolysin, as indicated by decreases in both T(j and area (AHd) of its endotherm. Chicken ovomucoid was slowly degraded by proteinase K (Fig. 9), a fungal serine proteinase that attacks many native proteins. Proteinase K, in accord with its subtilisin-1ike specificity (Kraus and Femfert, 1976), was inhibited by chicken ovoinhibitor, but not by chicken ovomucoid. In these non-inhibited systems, proteolysis can destabilize the inhibitor (substrate) protein, provided the susceptible bonds are accessible to the proteinase. Relevance of these examples to food systems derives from the role of proteolysis in protein deterioration (Feeney, 1980) and digestion. 

Friedman, M. (1982) Lysinoalanine formation in soybean protein kinetics and mechanism. In Food Protein Deterioration, Mechanism and Functionality. J.P. Cherry, ed. American Chemical Soc., Wash. p. 231. 

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