Patterns of extracellular proline-specific endopeptidases in Legionella and Flavobacterium spp. demonstrated by use of chromogenic peptides.

Some Legionella strains possess a strong extracellular proline-specific endopeptidase (PSE) activity. Using an enlarged selection of chromogenic peptides representing a variety of N-terminal amino-acids binding to a -prolyl-proline, paranitroanilide chain, PSE activity of Legionella and Flavobacterium strains was examined. Differences in PSE activity emphasized the importance of the chemical structure at the nonchromogenic end of the peptide substrates. There seem to be distinct patterns of N-terminal specificity of PSE in the two bacterial groups.