3-Hexulose Phosphate Synthase from a New Facultative Methylotroph, Mycobacterium gastri MB 19

Abstract

A newly found methanol-using bacterium, Mycobacterium gastri MB 19, is a facultative methylotroph which assimilates methanol via the ribulose monophosphate pathway. 3-Hexulose phosphate synthase was purified from the organism and characterized. This enzyme was found to use glycolaldehyde (Km =4.3 mM) and methylglyoxal (Km=5.7 mM) as well as formaldehyde (Km=1.4 mM) in the presence of D-ribulose 5-phosphate as an acceptor. The product of the condensation of glycolaldehyde with D-ribulose 5-phosphate was isolated by ionexchange chromatography. The dephosphorylated product was tentatively identified as a heptulose with the molecular formula C₇H₁₄O₇ from its spectrophotometric properties and GC-MS results.