THE FEEDBACK CONTROL OF SUGAR NUCLEOTIDE BIOSYNTHESIS IN LIVER

Abstract

Uridine diphosphite (UDP)-N-acetylglucosamine inhibits L-glutamine-D-fructose-6-phosphate transaminase, the first enzyme unique to its biosynthesis. Similarly, the formation of N-acetyl-mannosamine by UDP-N-acetylglucosamine 2-epimerase is inhibited by the end product, cytidine monophosphate (CMP)-N-acetylneuraminic acid. Compounds closely related to these inhibitors have little or no effect. The feedback inhibition of the L-glutamine-D-fructose-6-phosphate transaminase has been demonstrated in vivo by the administration of puromycin, which prevents the utilization of UDP-N-acetylglucosamine.