Springer Online Journal Archives 1860-2000
Abstract Malate dehydrogenase (MDH) (E.C.22.214.171.124) activity was detected in the filariaMolinema dessetae at a level similar to those found in other filariae. InM. dessetae, the cytoplasmic form (c-MDH) predominated and the study was performed on partially purified fractions. The pH optimum for oxaloacetate reduction was 6.1, with maximal activity at 7811 nmol min−1 mg protein−1, but high concentrations of oxaloacetate inhibited MDH activity. TheK m value for oxaloacetate was determined as 22 μM forM. dessetae c-MDH and 33μM for mammalian c-MDH. Anthelmintic drugs were compared as potential inhibitors of filarial and mammalian c-MDH. Among the compounds evaluated, amocarzine showed a specific inhibitory effect on filarial c-MDH through only at high concentrations. Suramin alone showed an inhibitory effect at low concentrations (K i=1.15 μM) but without selective action towards filarial c-MDH. The suramin type of inhibition was found to be competitive. Suramin probably acts on both enzymes in the same manner. Nevertheless,M. dessetae c-MDH is proposed as a suitable enzyme assay model to screen MDH inhibitors as potential filaricides.
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