Metabolism of alkyldihydroxyacetone phosphate in rat brain.
Alkyldihydroxyacetone-P is the first detectable product in the biosynthetic pathway for ether-linked glycerolipids that eventually leads to the formation of ethanolamine plasmalogens, a major constituent of myelin. During early postnatal development, the specific activity of NADPH2:alkyldihydroxyacetone-P oxidoreductase in microsomes from rat brain is maximum at 4-5 days after birth, the time when the specific activity of the enzymes that synthesize alkyldihydroxyacetone-P also peaks. For the oxidoreductase assay, we developed a thin-layer chromatographic method that separates alkyldihydroxyacetone-P as the dinitrophenylhydrazine derivative from its reduced product (alkylglycerol-P), with excellent resolution. Phosphohydrolases associated with brain microsomes exhibit optimal pH maximums at 5.2-5.6 and 7.5-7.8 for all three substrates tested -- alkyldihydroxyacetone-P, alkylglycerol-P and alkylacylglycerol-P. Alkylglycerol-P was most readily dephosphorylated under all experimental conditions. The enzyme(s) that dephosphorylates alkyldihydroxyacetone-P and alkylglycerol-P have similar properties with respect to Mg-2+ or EDTA; with both substrates, Mg-2+ had no effect and EDTA was highly stimulatory. In contrast, EDTA strongly inhibited the dephosphorylation of alkylaclglycerol-P and although Mg-2+ (1 mM) appeared to be required for optimal activity, higher levels inhibited the reaction.
D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D004099:Dihydroxyacetone Phosphate / Q000378:metabolism; D004492:Edetic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005459:Fluorides / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008055:Lipids / Q000096:biosynthesis; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D051381:Rats
D008055:Lipids; D004099:Dihydroxyacetone Phosphate; D004492:Edetic Acid; D000429:Alcohol Oxidoreductases; D010744:Phosphoric Monoester Hydrolases; D005459:Fluorides; D002118:Calcium