The hydrogenase of the pathogenic protozoan Trichomonas vaginalis was extracted and partially purified. The catalytic and spectroscopic properties of the enzyme indicate that it belongs to the class of [Fe]-hydrogenases, rather than the [NiFe]-hydrogenases. The hydrogenase activity was highly sensitive to carbon monoxide, 50% inhibition being attained by 1 μM CO. The EPR spectrum of the most active fractions from chromatography, after reduction by hydrogen and partial reoxidation under argon, showed an EPR spectrum at g = 2.10, 2.04, 2.00. This unusual spectrum is characteristic of the ‘H-cluster’, as seen in [Fe]-hydrogenases of anaerobic bacteria such as Clostridium spp.
