Thymidine Diphosphate 4-Acetamido-4,6-dideoxyhexoses

A pyridoxal phosphate-requiring transaminase which catalyzes a reversible reaction between thymidine diphosphate 4-keto-6-deoxy- d -glucose and l -glutamate to form TDP-4-amino-4,6-dideoxy- d -glucose and α-ketoglutarate has been purified 28-fold from an extract of Escherichia coli strain B. Some properties of the enzyme are reported. Transaminase activity is widely distributed among strains of E. coli, Salmonella, and Pasteurella pseudotuberculosis, but among the organisms studied only E. coli strain B has a transaminase which catalyzes the synthesis of TDP-4-amino-4,6-dideoxy- d -glucose. The other organisms have an enzyme which catalyzes the synthesis of the nucleotide containing the sugar with the d -galacto configuration.