Oxidation of glycerol to formaldehyde by rat liver microsomes

Rat liver microsomes catalyzed the oxidation of glycerol to a Nash-reactive material in a time- and protein-dependent manner. Omission of the glycerol or the microsomes or any of the components of the NADPH-generating system resulted in almost a complete loss of product formation. Apparent Km and Vmax values for glycerol oxidation were about 18 mM and 2.5 nmol formaldehyde per min per mg microsomal protein. Carbon monoxide inhibited glycerol oxidation indicating a requirement for cytochrome P-450. That the Nash-reactive material was formaldehyde was validated by a glutathione-dependent formaldehyde dehydrogenase positive reaction. These studies indicate that glycerol is not inert when utilized with microsomes or reconstituted mixed function oxidase systems, and that the production of formaldehyde from glycerol may interfere with assays of other substrates which generate formaldehyde as product.