Purification and composition studies of phosphoribosyladenosine triphosphate:pyrophosphate phosphoribosyltransferase, the first enzyme of histidine biosynthesis.

Highly purified preparations of iV-l-(S’-phosphoribosyl)adenosine triphosphate:pyrophosphate phosphoribosyltransferase from Salmonella fyphimurium have been obtained. The phosphoribosyltransferase is the first enzyme unique to histidine biosynthesis and is sensitive to feedback inhibition by histidine. The procedure used for purification preserved the histidine sensitivity of the enzyme. A molecular weight of 215,000 for native enzyme was obtained. In high concentrations of guanidine.HCl, the enzyme dissociated into several, perhaps identical, subunits. An amino acid analysis of one preparation is presented. Methionine has been detected as an NH%-terminal amino acid in the enzyme.