TRITRICHOMONAS-FETUS AND TRICHOMONAS-VAGINALIS - THE PATTERN OF INACTIVATION OF HYDROGENASE ACTIVITY BY OXYGEN AND ACTIVITIES OF CATALASE AND ASCORBATE PEROXIDASE

The concentration-dependence of the inhibition of whole-cell hydrogen formation by oxygen has been measured in the trichomonads Trichomonas vaginalis and Tritrichomonas foetus, and compared with the oxygen inhi bition of the in situ hydrogenase activity as measured by a tritium ex change assay. The inhibition profiles closely paralleled each other, s uggesting that hydrogenase is the primary site of inhibition of anaero bic fermentative metabolism. In addition the inhibition profile for is olated hydrogenosomes was measured and shown to be similar to that for whole organisms. Ascorbate peroxidase was shown to be present in both organisms whereas catalase was confirmed to be present only in Tritr. foetus. The kinetic parameters of both enzymes were measured and thei r respective roles in oxygen protection discussed.