TIME-DEPENDENT INCREASE IN URIDINE DIPHOSPHATE GLUCOSE PYROPHOSPHORYLASE ACTIVITY IN VITRO

UDPGlc pyrophosphorylase (UTP:α-d-glucose-l-phosphate uridyltransferase, EC 2.7.7.9) activity increases upon incubation of extracts prepared from a variety of sources including organ cultures of rat mammary glands. The increase of enzymatic activity is dependent upon temperature, concentration of extract, pH and urea concentration. The activation" process does not alter the Km for UTP or molecular weight of the enzyme. The present evidence indicates that the increase in activity is due to a process leading to a more active form of the enzyme. © 1969."