Enzymes involved in the formation of glycerol 3-phosphate and the by-products dihydroxyacetone and glycerol inZymomonas mobilis

In Zymomonas mobilis a novel pathway for the formation of glycerol 3-phosphate was identified by enzymatic studies and nuclear magnetic resonance spectroscopy. This pathway branches off from the Entner-Doudoroff pathway at the intermediate glyceraldehyde 3-phosphate and proceedes via dihydroxyacetone phosphate, dihydroxyacetone, glycerol to glycerol 3-phosphate. The reaction sequence is catalyzed by the enzymes triosephosphate isomerase (0.4 U (mg protein)−1), dihydroxyacetone phosphatase (0.31 U (mg protein)−1), dihydroxyacetone reductase (0.25 U (mg protein)−1), and glycerokinase (0.08 mU (mg protein)−1), respectively. The action of a postulated aldolase catalyzing the cleavage of fructose 6-phosphate to dihydroxyacetone and glyceraldehyde 3-phosphate could be excluded.