Characterization and comparison of aminopeptidase activity of various strains of Mycobacterium tuberculosis.

The aminopeptidase activity of three strains of Mycobacterium tuberculosis, H37Rv, H37Ra, and M. tuberculosis from a patient, was partially purified and characterized. The activity from all three organisms was found to be very similar, if not identical. All three aminopeptidases eluted at a similar salt concentration on DEAE Bio-Gel; were active on the same synthetic and peptide substrates; had molecular weights of 75-76,000; were found to be stable between pH 5 and 8, and 4 degrees and 40 degrees C; and had a pH optimum of 7. They were inhibited by low concentrations of Hg2+, Cu2+ and Co2+; metal chelators; and 4-chloromercuribenzoic acid. A number of amino acids and several antibiotics were also found to be inhibitory. Of the antibiotics tested, rifampicin and bacitracin were the most effective.