Endopeptidases proteinase activity

Aspartic endopeptidases (EC 3.4.23) are the best-known aspartic hydrolases and the only ones to be presented here. These enzymes were formerly called acid proteinases because most of them are active at low pH. In con-... 

The predominant NSLAB in Cheddar and Dutch-type cheeses are meso-philic Lactobacillus, which possess a cell wall-associated and intracellular proteinases. A range of intracellular peptidases, including dipeptidases, aminopeptidases, and endopeptidases, have been identified in Lactobacillus (see reviews by Khalid and Marth 1990a Peterson and Marshall, 1990). Interestingly, carboxypeptidase activity, which has not been found in lacto-cocci, has been reported in Lactobacillus casei (El Soda et al., 1978). 

Proteinases catalyze the hydrolysis of peptide linkages in proteins. Those proteinases which have been purified have also been shown to have peptidase activity, that is, they catalyze the hydrolysis of synthetic polypeptides of known structure. Because the proteinases split proteins to yield lower molecular weight peptones, proteoses, and peptides they have been termed endopeptidases they are capable of hydrolyzing peptide bonds that are not terminal. Exopeptidases can hydrolyze only peptide bonds that involve terminal amino acids. The synthesis of peptide substrates has been authoritatively reviewed by Fruton. ... 

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