Thymidine Diphosphate 4-Acetamido-4,6-dideoxyhexoses

Abstract

The first step in the biosynthesis of thymidine diphosphate 4acetamido-4,6-dideoxyhexoses(2) or of TDP-L-rhamnose (3-5) in bacteria is the formation of TDP-4-keto&deoxy-u-glucose from TDP-n-glucose.This transformation involves oxidation of glucose, bound to the nucleotide, at C-4, loss of a molecule of water and reduction at C-6.The exact mechanism and sequence of these over-all changes are unknown.Subsequent reactions of TDP-4-keto-B-deoxy-n-glucose, transamination and acetylation at C-4, or epimerization at C-3 and C-5 with reduction at C-4, then lead to formation either of t,he acetamido sugars or of L- rhamnose.The purpose of the present paper is to report on the purification from an extract of Escherichia coli strain B and some of the properties of the enzyme which catalyzes the formation of TDP-4-keto-6-deoxy-D-glucose.This enzyme has been called TDP-Dglucose oxidoreductase.