The use of aminopeptidase substrate specificity profiles to identify leptospires

Thirty reference Leptospira strains and twelve leptospire-like cultures were examined for aminopeptidase activity using twenty-two aminoacyl-beta-naphthylamide substrates. Aminopeptidase activity was demonstrated in extracts of each of the cultures and their substrate specificity profiles compared using several computer analysis procedures. The specificity profiles were consistent for each of the strains examined. Leptospira were readily differentiated from non Leptospira strains. This was supported by DNA base ratios calculated for the strains. Of the non Leptospira strains, seven appeared similar to the "L. illini" cultured included. Two of these strains, which included the strain "L. parva" sp. nov., formed a subgroup of this "L. illini" group. Substrate specificity profiles for the L. interrogans and L. biflexa strains examined were also different from each other.