Hydrogen transfer by NADPH-dependent reductases in elongation of very-long-chain saturated and polyunsaturated fatty-acyl-CoA in swine cerebral microsomes.
The hydrogen transfer from NADPH was studied in the elongation of arachidoyl-CoA (20:0-CoA) and arachidonoyl-CoA (20:4-CoA) in swine cerebral microsomes. Previously, we showed that four deuterium atoms (2H) were transferred stereospecifically from (4S)-[4-2H1]NADPH in the elongation of 20:0-CoA to 24:0 (Yoshida, S., Takeshita, M. and Kawaguchi, A. (1984) Biochem. Biophys. Res. Commun. 124, 322-328), and that three deuterium atoms were transferred from 2H2O in the elongation of 20:4-CoA to 22:4. The deuteride transfer from (4S)-[4-2H1]NADPH was observed in the elongation of 20:4-CoA to 24:4, by the technique of mass fragmentography using the chemical ionization method, and, in this case, two 2H were transferred to 24:4. No deuteride was transferred from (4R)-[4-2H1]NADPH in the elongation of 20:0-CoA and 20:4-CoA. Moreover, the condensation product (3-keto-fatty-acyl-CoA) which was formed in the elongation without NADPH could be reduced by the addition of NADPH and sodium hydrosulfite, for the elongation of 16:0-CoA and 20:4-CoA, while the condensation product from 20:0-CoA could be reduced only by NADPH, but not by hydrosulfite. The hydrosulfite did not produce the final elongation products from 20:0-CoA, 16:0-CoA or 20:4-CoA. These results suggested that the hydride was transferred from NADPH stereospecifically only in the elongation of 20:0-CoA in the step of 3-ketoacyl-CoA reduction by the reductase which might be different from that for the elongation of 16:0-CoA and 20:4-CoA in which the proton exchange might occur via a water proton in the reduction of 3-ketoacyl-CoA. Accordingly, the hydride transfer might occur from NADPH in the step of 2,3-enoyl reduction in the elongation of 20:0-, 16:0- and 20:4-CoA.
Yoshida
S
S
Department of Biochemistry, Medical College of Oita, Japan.
Saitoh
T
T
Takeshita
M
M
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D003903:Deuterium / Q000378:metabolism*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D008861:Microsomes / Q000201:enzymology; D009249:NADP / Q000378:metabolism* / Q000494:pharmacology; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D013447:Sulfites / Q000494:pharmacology; D013552:Swine
D000214:Acyl Coenzyme A; D013447:Sulfites; C042140:arachidoyl-coenzyme A; C026563:arachidonyl-coenzyme A; D010171:Palmitoyl Coenzyme A; D009249:NADP; D003903:Deuterium; D044943:Fatty Acid Desaturases; C042345:hydrogen sulfite