N-acetyl-beta-D-hexosaminidase from Trichomonas vaginalis: substrate specificity and activity of inhibitors.

Among chitinolytic activities previously described in Trichomonas vaginalis, N-acetyl-beta-D-hexosaminidase (NAHase) was the enzyme system expressing the highest level of specific activity. We report here some biochemical characteristics of NAHase purified from T. vaginalis. We found at first that the use of 4-methylumbellifferyl-substrate was responsible for a substrate affinity for the enzyme, about 1000-fold higher than those when using p-nitrophenyl-substrates (PNP). Whereas the optimum pH was 7.0 using PNP-substrate, it was at 4.5 using 4-methylumbelliferyl-substrate. Four different substrates were compared for their action on T. vaginalis NAHase and we have found that N-acetyl-beta-D-glucosaminide substrate was the most specific. DTT had no effect on enzyme activity suggesting that thiol group are not involved at the catalytic site. The use of previously described inhibitors showed a positive correlation between trichomonacidal activity and NAHase inhibition.

Synthesis and biological evaluation of ureido and thioureido derivatives of 2-amino-2-deoxy-D-glucose and related aminoalcohols as N-acetyl-beta-D-hexosaminidase inhibitors.

Ureido and thioureido derivatives of 2-acetamido-2-deoxy-beta-D-glucose, 1-amino-1-deoxy-D-glucitol and 2-(2-aminoethoxy)ethanol were prepared as N-acetyl-beta-D-hexosaminidase (NAHase) inhibitors and were evaluated on Trichomonas vaginalis NAHase. Although none showed complete inhibition of the enzyme at 100 microM, 1-amino-1-deoxy-D-glucitol derivatives acted as competitive inhibitors of the NAHase of T. vaginalis.