Nutritional and functional improvement of food proteins through the covalent attachment of essential amino acids (Abstract)

✍ Scribed by Puigserver, A. J. ;Gaertner, H. F.

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 112 KB
• Volume: 30
• Category: Article
• ISSN: 0027-769X
• DOI: 10.1002/food.19860300380

✦ Synopsis

Since in vitro hydrolysis of polymethionyl-casein by enzymes of the digestive tract gave rise to an equal relative release of all the amino acids, thus indicating that covalently attached methionine polymers are likely to be biologically available, hydrolysis of the polymers was further investigated.

Model isopeptides corresponding to various chain lengths of polythionine (2-5 residues) linked to the &-amino group of lysine were synthesized by stepwise solid phase procedures according to the method of MERRIFIELD. Hydrolysis of these peptides by pepsin, chymotrypsin, cathepsin C (dipeptidyl peptidase IV) and aminopeptidase N was investigated using high performance liquid chromatography to identify and quantify the hydrolysis products. From pepsin digestion studies, it emerged that methionine oligomers covalently attached to the &-amino gtoup of lysine were essentially cleaved to tripeptides provided they contained at least 4 residues. On the other hand, chymotrypsin preferentially hydrolyzed the methionyl-methionine