Protein digestion specificity

The hydrolysis of zeaxanthin esters by a carboxyl ester lipase indeed enhanced both the incorporation of zeaxanthin in the micellar phase and uptake of zeaxanthin by Caco-2 cells. As mentioned earher, carotenoids can also be linked to proteins by specific bindings in nature and these carotenoid-protein complexes may slow the digestion process and thus make their assimilation by the human body more difficult than the assimilation of free carotenoids. Anthocyanins are usually found in a glycosylated form that can be acetylated and the linked sugars are mostly glucose, galactose, rhamnose, and arabinose. 

The protein content of milk is primarily influenced by the breed of cow, the stage of lactation, type of diet being fed and the health status of the cow, and is important in processing because the protein (and specifically casein) content of milk determines its cheese yield. Milk provides a highly digestible source of protein for a large proportion of the world s population, either as raw milk or processed into dairy products. In addition to this basic nutrition, milk... 

Role of PI in membrane protein anchoring Specific proteins can be covalently attached via a carbohydrate bridge to membrane-bound PI (Figure 17.9). [Note Examples of such proteins include alkaline phosphatase (a digestive enzyme found on the surface of the small intestine that attacks organic phosphates), and acetylcholine esterase (an enzyme of the postsynaptic membrane that... 

Trypsin, chymotrypsin, and elastase are three of the most important protein-digesting enzymes secreted by the pancreas. Despite their similarities they have different substrate specificity, that is, they cleave different peptide bonds during protein digestion. 

The strength of MS in proteomic research becomes apparent when a protein to be studied is first digested by using one or more proteolytic enzymes that can cleave proteins at specific residues, producing a characteristic and unique fingerprint of tens to... 

Two important zinc metalloenzymes in protein digestion are the pancreatic carboxypeptidase A and B. A loss of activity of the pancreatic carboxyeptidase A in zinc deficiency is a consistent finding (91), According to some investigators, within two days of institution of zinc-deficient diet in rats, the enzyme lost 24% of its activity, and within three days of dietary zinc repletion, the activity of pancreatic carboxypeptidases is restored to normal levels (91). These results indicate that the level of food intake has no influence and that a decreased activity of carboxypeptidase A in the pancreas was related specifically to a dietary lack of zinc. As in the case of the alkaline phosphatase, the amount of carboxypeptidase A apoenzyme present appears to be diminished in zinc-deficient pancreas. 

Lectins bind to specific receptor sites on the surface of epithelial cells in the intestines which leads to a nonspecific interference with the absorption of nutrients (Liener, 1980, cited in (4)). However, the phytohemagglutinating activity can be easily eliminated by dry or thermal treatments (Liener, 1980, cited in 4)). In vitro protein digestibility of T. indica is 71.6%, which is comparable to the levels reported for Glycine max (Gross, 1982, cited in 4)). 

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