Evidence for uridine 5′-(α-D-galactopyranosyl pyrophosphate):NAD 2-hexosyl oxidoreductase in [formula omitted

Abstract

A heat labile fraction from Penicillium charlesii was isolated which catalyzes the oxidation of UDP-galactose in the presence of NAD+ with the formation of NADH and a 2-keto sugar presumably attached to UDP. A portion of this sugar is in the furanosyl form. A mechanism for conversion of the pyranosyl to furanosyl ring form is proposed and UDP-2-ketogalactopyranoside and UDP-2-ketogalactofuranoside are suggested as intermediates in the conversion of uridine 5′-(α-D-galactopyranosyl pyrophosphate) to uridine 5′-(α-D-galactofuranosyl pyrophosphate).