Characterization of fatty acid elongation system in porcine neutrophil microsomes.
Microsomes purified from porcine neutrophils containing the fatty acid chain-elongation system for long- and very-long-chain fatty acyl-CoAs, and several enzymatic characters for the elongation of palmitoyl-CoA (16:0-CoA) and arachidoyl-CoA (20:0-CoA) were examined. The heat-inactivation profile for the elongation of 16:0-CoA was different from that of 20:0-CoA, suggesting the presence of different enzyme systems for palmitoyl-CoA and arachidoyl-CoA. Contrary to the elongation system of brain microsomes, the successive synthesis of lignoceric acid (24:0) from 20:0-CoA at 60 microM was not prominent under normal conditions in the neutrophil microsomes. The synthesis of behenic acid (22:0) was slightly inhibited by 0.5 mM N-ethylmaleimide (NEM) present in the assay mixture, whereas the pre-treatment of microsomes with 0.5 mM NEM largely inhibited the synthesis of 22:0 from 20:0-CoA. The synthesis of 24:0, however, was enhanced by 0.5 mM NEM in the elongation of 20:0-CoA and the rate of 24:0 synthesis became dominant over the synthesis of 22:0. These results suggested that the elongation enzyme for very-long-chain fatty acyl-CoA, especially for 20:0-CoA elongation to 22:0 in the neutrophil microsomes contained NEM-sensitive sulfhydryl groups in the active center and the mechanism for the synthesis of 24:0 through successive elongation from 20:0-CoA was different from that of 22:0, as the former was enhanced by NEM whereas the latter was strongly inhibited.
Kugi
M
M
Department of Biochemistry, Medical College of Oita, Japan.
Yoshida
S
S
Takeshita
M
M
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000648:ultrastructure; D005033:Ethylmaleimide / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008316:Malonyl Coenzyme A / Q000378:metabolism; D008861:Microsomes / Q000187:drug effects / Q000201:enzymology*; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology; D009504:Neutrophils / Q000648:ultrastructure*; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D013552:Swine
D000214:Acyl Coenzyme A; D005227:Fatty Acids; D009243:NAD; C042140:arachidoyl-coenzyme A; D010171:Palmitoyl Coenzyme A; D008316:Malonyl Coenzyme A; D009249:NADP; D005033:Ethylmaleimide