Inhibition of glycosidases by aldonolactones of corresponding configuration. The specificity of α-l-arabinosidase

Abstract

The previous study (Conchie, Gelman and Levvy, 1967b) of the specificity of [beta]-gluco-sidase, [beta]-galactosidase and [beta]-D-fucosidase in barley, limpet, almond emulsin and rat epididymis was extended to [alpha]-L-arabinosidase. The inhibitory action of L-arabinono-(1[forward]5)-lactone was tested against all 4 types of enzyme, and [alpha]-L-arabinosidase was examined for inhibition by glucono-, galactono- and D-fucono-lactone. In emulsin, the enzyme that hydrolzes [beta]-glucosides, [beta]-galactosides and [beta]-D-fucosides also hydro-lyzes [alpha]-L-arabinosides. Rat epididymis resembles emulsin except that, as already noted, it lacks [beta]-glucosides activity. In the limpet, [beta]-L-arabinosidase activity is associated with the enzyme that hydrolyzes [beta]-glucosides and [beta]-D-fucosides, and not with the separate [beta]-galacto-sidase. The effects of the different lactones on the barley preparation suggest that [beta]-L-arabinosides activity is associated with the [beta]-galacto-sidase rather than with the enzyme that hydrolyzes [beta]-glucosides and [beta]-D-fucosides. Fractionation and heat-inactivation experiments indicate that there is also a separate [alpha]-L-arabinosidase in the preparation.