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Trypanosoma brucei: Suramin and other trypanocidal compounds' effects on sn-glycerol-3-phosphate oxidase

1977; Elsevier BV; Volume: 43; Issue: 2 Linguagem: Inglês

10.1016/0014-4894(77)90040-6

1090-2449

Alan H. Fairlamb, I.B.R. Bowman,

Trypanosoma species research and implications

A number of chemotherapeutic compounds effective against Trypanosoma brucei were tested as inhibitors of the purified glycerophosphate oxidase (sn-glycerol-3-phosphate: oxygen oxidoreductase). Of these, melarsen oxide and suramin were found to be potent inhibitors of the dehydrogenase component of this multienzyme complex. Suramin is a potent competitive inhibitor of the oxidase with a Ki of 4.1 μM with respect to glycerophosphate. The Km for glycerophosphate for the enzyme was found to be decreased from 6.5 to 1.7 mM in the presence of bovine serum albumin while the Vmax was increased two- to threefold. Human and bovine serum albumin can protect the oxidase from inhibition by suramin, by preferential binding of the drug. Analogs of suramin with little or no chemotherapeutic value are less effective inhibitors of the oxidase, and the correlation between therapeutic action and potency as inhibitors suggests that this enzyme is one of the principal sites of action of suramin in vivo.