Human Hypoxanthine-Guanine Phosphoribosyltransferase

Abstract

Abstract Hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) has been purified to homogeneity from human erythrocytes obtained from one male donor. The normal human enzyme has a Stokes radius of 36 A with a molecular weight of 68,000 and is composed of two subunits which have identical molecular weight and net charge. Three isoenzymes were reproducibly distinguished by preparative isoelectric focusing. This electrophoretic heterogeneity appears to result from a nongenetic, post-transcriptional alteration of one or both subunits.