Human Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT): Purification and Properties

Abstract

Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) (E.C. 2.4.2.8.) catalyzes the formation of guanosine-5’-monophosphate and inosine-5’-monophosphate from 5’-phosphoribosyl-l-pyrophosphate (PPribose-P) and the purine bases guanine and hypoxanthine, respectively. Although originally assigned simply a “salvage” function in purine metabolism, the discovery of a virtually complete, X-linked deficiency of HGPRT associated with hyperuricemia, hyperuricaciduria and a bizarre neurologic syndrome (Lesch-Nyhan syndrome) has led to a reevaluation of the importance of HGPRT in the regulation of purine metabolism and central nervous system function (Seegmiller, Rosenbloom and Kelley, 1967). Therefore, an analysis of the structure of the normal enzyme is necessary to provide a basis for understanding the genetic lesion(s) producing altered or absent enzyme function. We have purified HGPRT to homogeneity from non-pooled, human male erythrocytes and have attempted to elucidate the nature of the electrophoretic heterogeneity of HGPRT activity observed during the purification (Arnold and Kelley, 1971; Kelley and Arnold, 1973).