Zur Kenntnis des intermediären Stoffwechsels des Histidins Trennung von Histidase und Urocaninase. 6. Mitteilung

Abstract

Histidase which yields NH3 from [iota]-histidine and urocanicase which produces it from urocanic acid were each prepared, in the form of an extract free of the other, by preferential adsorption from an aq. extract of rat liver made by grinding with sand and water and clarifying with kaolin. The histidase was adsorbed on Pb phosphate at pH 5.3 and eluted with a phosphate buffer soln. at pH 8.0. Incubation of the eluate at pH 8.0 with histidine produced NH3, with urocanic acid, essentially none. The urocanicase was adsorbed on Cas3(PO4)2 and eluted, also with phosphate buffer at pH 8.0. The eluate contained urocanicase, but essentially no histidase. Histidase hydrolyzes [iota]-histidine, even in the absence of urocanicase. Urocanic acid suppresses the action of histidase on [iota]-histidine but has no effect on urocanicase activity.