Enzyme-Hydrolyzed Protein

D9. de Verdier, C. H., and Agren, G., Paper chromatographic analysis of amino acids and peptides in tissue extracts and enzyme hydrolyzed proteins. Acta Chem. Scand. 2, 783-796 (1948). 

A group of enzymes found in many common household products is the proteases. These enzymes hydrolyze proteins into free amino acids. The proteases in meat tenderizer make steak more tender by breaking down the proteins. ... 

Protein digestion takes place in the stomach and the small intestine. Here, digestive enzymes hydrolyze proteins to smaller peptides and amino acids, which pass through the walls of the intestines, are absorbed by the blood, and are transported to the liver and other tissues of the body. The body does not store free amino acids. They are used to synthesize... 

Antitumor enzyme, hydrolyzes L-asparagine in bloodstream, depriving tumor cells of the essential amino acid results in inhibition of protein, DNA, and RNA synthesis and cell proliferation derived from Escharichia coli... 

Protease Any one of numerous enzymes that hydrolyze proteins. 

Peptide hydrolases (peptidases or proteases, i.e., enzymes hydrolyzing peptide bonds in peptides and proteins, see Chapt. 2) have received particular attention among hydrolases. As already described in Chapt. 2, peptidases are divided into exopeptidases (EC 3.4.11 -19), which cleave one or a few amino acids from the N- or C-terminus, and endopeptidas-es (proteinases, EC 3.4.21-99), which act internally in polypeptide chains [2], The presentation of enzymatic mechanisms of hydrolysis in the following sections will begin with peptidases and continue with other hydrolases such as esterases. 

Various pancreatic enzymes hydrolyze lipids, including lipase with its auxiliary protein colipase (see p. 270), phospholipase A2, and sterol esterase. Bile salts activate the lipidcleaving enzymes through micelle formation (see below). 

Biological detergents and washing powders use lipase enzymes to break down fats, and protease enzymes that hydrolyze proteins from food stained fabrics. 

Alpf receptors are coupled via G proteins in the Gq family to phospholipase C. This enzyme hydrolyzes polyphosphoinositides, leading to the formation of inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) (Table 9-1, Figure 9-1). IP3 promotes the release... 

Sekul et al. (29) studied the nitrogen solubility properties of enzyme-hydrolyzed peanut proteins. A deionized water dispersion of peanut flour (1 10, w/v) was treated with papain (0.5% total volume) at 45OC for 15 min. Solubility was tested over a range of pH 1 to 9. In general, papain treatment improved solubility at all levels examined except pH 2 and 8 (Figure 6). 

Many enzymes are named by adding the suffix -ase to a word, or words, descriptive of the type of enzymatic activity. Thus, esterases hydrolyze esters, proteinoses hydrolyze proteins, reductases achieve reductions, and synthetases achieve syntheses of polypeptide chains, nucleic acid chains, and other molecules. 

Walters and Loring (88) have purified a 3 -nucleotidase about 50-fold from mung bean sprouts (Phaseolus aureus Roxb.). The enzyme hydrolyzes 3 -AMP, 3 -GMP, 3 -CMP in decreasing order and also hydrolyzes the 3 -phosphate group of coenzyme A. (89), but it has no significant activity for 2 - or 5 -ribonucleotides. For 3 -GMP, 3 -AMP, 3 -UMP, and 3 -CMP, Km values are 0.67, 1.1, 7.7, and 15 mM, respectively. The enzyme preparation also contained acid stable ribonuclease activity (89). Both 3 -nucleotidase and acid ribonuclease were inactivated reversibly at pH 5.0 and by dialysis and this inactivation could be prevented by Zn2+. The two activities were similarly inactivated by heat at pH 5 and 7.5. Such data indicate that the two are metalloproteins— probably zinc metalloproteins. These similarities and other kinetic data provide evidence that the 3 -nucleotidase and ribonuclease activities reside in the same protein. 

Let us first consider the situation under conditions of nitrogen excess (see fig. 21.5). The first regulatory protein in the cascade is converted into a uridylyl-removing enzyme. This enzyme hydrolyzes UMP from a PII 3 UMP protein that acts in concert with adenylyltransferase to form adenylate glutamine synthase. The resulting adenylylated enzyme is inactive. 

Originally enzymes were given nondescriptive names such as rennin curding of milk to start cheese-making processcr pepsin hydrolyzes proteins at acidic pH trypsin hydrolyzes proteins at mild alkaline pH... 

A major aim of enteric coating is protection of drugs that are sensitive or unstable at acidic pH. This is particularly important for drugs such as enzymes and proteins, because these macromolecules are rapidly hydrolyzed and inactivated in acidic medium. Antibiotics, especially macrolide antibiotics like erythromycin, are also rapidly degraded by gastric juices. Others, such as acidic drugs like NSAID s (e.g., diclofenac, valproic acid, or acetylsalicylic acid) need to be enteric coated to prevent local irritation of the stomach mucosa. 

Morino and Snell32 reduced holotryptophanase with NaBIL and isolated -pyridoxyl-lysine from the hydrolyzed protein. Subsequent isolation of the pyridoxyl-containing peptide50 and determination of its position in the total amino acid sequence of the enzyme led to identification of Lys-270, which forms a Schiff base with PLP. 

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