Serological, Taxonomic, and Kinetic Studies of the T and M Classes of Mycobacterial Catalase

Abstract

Two types of catalase may be found in extracts of mycobacteria, the heat-labile T class and the heat-stable M class. The T-catalase is resistant to 3-amino-1,2,4-triazole and has a Michaelis constant in the range of 3.1 to 6.8 mM H2O2, whereas the M-catalase is inhibited by 3-amino-1,2,4-triazole and has a Michaelis constant in the range of 143 to 156 mM. Some species of mycobacteria produce only one class of catalase, and others produce both. Of the species studied, only Mycobacterium terrae, M. triviale, and M. nonchromogenicum failed to exhibit T-catalase, although all three of these species had M-catalase. Conversely, M. tuberculosis, M. bovis, M. intracellulare, M. avium, M. gastri, M. marinum, and M. xenopi yielded T-catalase but not M-catalase. Six species, M. szulgai, M. simiae, M. kansasii, M. gordonae, M. scrofulaceum, and M. asiaticum, produced both classes. The differences in resistance to heat and 3-amino-1,2,4-triazole were exploited in the development of methods for quantitative serological characterization of one class of catalase in the presence of the other. These techniques were used with three reference sera to produce a branching diagram of divergence of the T-catalases from 13 species of mycobacteria based on measurements of immunological distance. No T-catalase could be demonstrated in another three species. A first-stage study was also carried out with a single reference antiserum to M-catalase from M. kansasii. Representatives of nine mycobacterial species, including the three that produced no T-catalase, were characterized with this reference system, which tends to yield larger immunological distance values than the T-catalase system.