A number of clones were isolated from a subsp. lactis gene library capable of hydrolysing the chromogenic substrate Gly-Ala-β-naphthylamide (Gly-Ala-βNA). Some of the recombinant plasmids carried by these clones have been shown to encode the cysteine aminopeptidase gene Nucleotide sequence analyses of the plasmid inserts of the remaining clones resulted in the identification of two adjacent ORFs encoding proteins exhibiting a high degree of similarity between themselves (72.6%) and with One gene, designated was overexpressed in and the crude extracts obtained were shown to be peptidolytically active both against chromogenic substrates and peptides, and in a growth test. PepC and PepG activities were compared using chromogenic βNA and p-nitroanilide substrates and leucine or proline-containing peptides were applied in growth experiments of recombinant The results indicate that the enzymes, although structurally related, have different substrate preferences. No enzyme activity could be ascribed to the second ORF (), despite the production of a visible protein using a T7 RNA polymerase system. Primer extension analysis, using mRNA isolated from subsp. DSM7290 did establish that was transcribed.


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