3.4.21.92 Hydrolysis of proteins to small peptides in the presence of ATP and Mg2+. alpha-Casein is the usual test substrate. In the absence of ATP, only oligopeptides shorter than five residues are hydrolysed (such as succinyl-Leu-Tyr-/-NHMec, and Leu-Tyr-Leu-/-Tyr-Trp, in which cleavage of the -Tyr-/-Leu- and -Tyr-/-Trp bonds also occurs) dual mechanism in which translocation alternates with proteolysis, allowing peptides of more or less unifirm length to be cleaved processively from a translocating substrate 667634 3.4.21.92 Hydrolysis of proteins to small peptides in the presence of ATP and Mg2+. alpha-Casein is the usual test substrate. In the absence of ATP, only oligopeptides shorter than five residues are hydrolysed (such as succinyl-Leu-Tyr-/-NHMec; and Leu-Tyr-Leu-/-Tyr-Trp, in which cleavage of the -Tyr-/-Leu- and -Tyr-/-Trp bonds also occurs) in presence of ATP and Mg2+. In the absence of ATP only oligopeptides shorter than five residues are hydrolyzed -