Microcalorimetric studies on the non-competitive inhibition of bovine liver arginase

Abstract

Two methods, e.g. initial rate method and thermokinetic reduced extent method were presented for studies on non-competitive inhibition. Arginase-catalyzed the hydrolysis of L-arginine toL-ornithine and urea and the inhibition of this reaction by sodium fluoride were studied in the absence and presence of exogenous of Mn2+at 37°C in 40 mM sodium barbiturate-hydrochloric acid buffer solution (pH 7.4). Both methods were successively used to determine the values of K1. The advances and disadvantages of each method were compared in this paper. Exogenous Mn2+ could result in more sensitivity of arginase to F-1. Since the inhibition of arginase by F-1 depends on the pH values of the reaction system and behave as a non-competitive inhibition, it probably due to its small volume and high electronic density allow it access to the activity site of the enzyme and replaces of µ-OH2 (or µ-OH) as the bridge ligand with Mn(II, II) cluster. However, further studies are necessary to determine the modes of interaction of F-1 with bovine liver arginase.