The peptide hydrolase system of Lactobacillus reuteri

Peptide hydrolase system of Lactobacillus reuteri CRL 1098, a lactic acid bacteria of sourdough origin, was investigated. This microorganism has a broad range of peptidases consisting of an active aminopeptidase, X-Prolyl-dipeptidylaminopeptidase, dipeptidase and tripeptidase. Aminopeptidase, iminopeptidase and endopeptidase are most likely located in the cytoplasmic fraction showing no detectable association with the cell membrane, while dipeptidase and tripeptidase are mainly associated with the latter fraction. The peptidases are metalloenzymes activated by Co²⁺ and inhibited by Cu²⁺, Hg²⁺, Cd²⁺ and by metal-complexing reagents. The aminopeptidase activity inhibited by EDTA can be restored by Mn²⁺ while that of di- and tripeptidase treated with 1,10-phenantroline can be restored by Zn²⁺ and Co²⁺, respectively.