Chinese hamster hypoxanthine-guanine phosphoribosyltransferase. Purification, structural, and catalytic properties.

摘要: Abstract Hypoxanthine-guanine phosphoribosyltransferase from Chinese hamster brain, liver, and V79 tissue culture cells appears to have identical structural catalytic properties. The enzyme has been purified 540-fold apparent homogeneity brain. native molecular weight is 78,000 85,000 determined by Sephadex G-100 column chromatography acrylamide gel electrophoresis. consist of three subunits 25,000 sodium dodecyl sulfate Electrofocusing electrophoresis demonstrate the presence at least isozymes. remarkably stable 85° if first incubated in 1 mm 5-phosphoribosyl 1-pyrophosphate. active pH 5.5 11 with maximum activity 10. displays Michaelis-Menten kinetics Michaelis constants for hypoxanthine, guanine, phosphoribosylpyrophosphate 0.52, 1.1, 5.3 µm, respectively.