Glycosidase Activities of Mycoplasmas

Abstract The activities of α- and β-glucosidase, β-galactosidase and β-N acetylglucosaminidase were assessed at acidic pH by fluorimetry using the appropriate 4-methylumbelliferyl substrate in four Mycoplasma species ( M. pneumoniae, M. gallisepticum, M. hominis and M. capricolum ) and in Acholeplasma laidlawii . The glycosidase activities were in a low range (0.1–4.2 nmole per h per mg protein) with the exception of higher activities of β-N-acetylglucosaminidase in A. laidlawii . The enzyme levels of a virulent and a nonvirulent strain of M. pneumoniae were comparable. Despite the very sensitive assay, neuraminidase activity was not detected in M. pneumoniae and M. gallisepticum . No induction of a-glucosidase could be demonstrated for M. pneumoniae or A. laidlawii . At least part of the glycosidase activities was localized in the membrane fraction of all mycoplasmas studied. This may support the hypothesis that pathogenic mycoplasmas, being membrane parasites, may modify, by their glycosidases, some host cell glycoconjugates. However, our study did not distinguish the pathogenic mycoplasmas to possess a characteristic glycosidase profile.