however , a significant exchange of label between [ 32p ] pyrophosphate and 5-phosphoribosyl-alpha-1-pyrophosphate is observed upon incubation with this enzyme , suggesting that hypoxanthine-guanine phosphoribosyltransferase may exist , in part , as a phosphoribosyl-enzyme complex in the presence of 5-phosphoribosyl-alpha-1-pyrophosphate .
C0014442
enzyme
C0026741
enzyme complex