Product identification and determination of optimal condition of 8, 11, 14-eicosatrienoic acid desaturation in rat liver microsomes.
delta 5-Desaturation of 8, 11, 14-eicosatrienoic acid in washed rat liver microsomes was studied in the presence of NADH, ATP, and coenzyme A. The product was identified as arachidonic (5, 8, 11, 14-eicosatetraenoic) acid by radiogaschromatography. Cytosol fraction stimulated delta 5-desaturation but did not participate in 8, 11, 14-eicosatrienoyl-CoA synthesis. The pH optimal to the desaturation was 6.8. The minimal concentrations of ATP and pyridine nucleotides which gave the maximal desaturation activity were 2 mM and 0.75 mM, respectively. Both NADH and NADPH were able to be electron donors for delta 5-desaturase, but cytochrome P-450 did not take part in the enzyme reaction because CO gas did not inhibit its activity. Apparent Km and Vmax for 8, 11, 14-eicosatrienoic acid were 18 microM and 154 pmol/min/mg, respectively.
D015126:8,11,14-Eicosatrienoic Acid / Q000032:analysis*; D000818:Animals; D002849:Chromatography, Gas; D003579:Cytochrome Reductases / Q000378:metabolism; D042966:Cytochrome-B(5) Reductase; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000032:analysis*; D008862:Microsomes, Liver / Q000201:enzymology*; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000032:analysis; D051381:Rats
D005231:Fatty Acids, Unsaturated; D009243:NAD; D009249:NADP; D044943:Fatty Acid Desaturases; D003579:Cytochrome Reductases; D042966:Cytochrome-B(5) Reductase; D015126:8,11,14-Eicosatrienoic Acid