Peroxisomal beta-oxidation of long-chain fatty acids possessing different extents of unsaturation.
Rates of peroxisomal beta-oxidation were measured as fatty acyl-CoA-dependent NAD+ reduction, by using solubilized peroxisomal fractions isolated from livers of rats treated with clofibrate. Medium- to long-chain saturated fatty acyl-CoA esters as well as long-chain polyunsaturated fatty acyl-CoA esters were used. Peroxisomal beta-oxidation shows optimal specificity towards long-chain polyunsaturated acyl-CoA esters. Eicosa-8,11,14-trienoyl-CoA, eicosa-11,14,17-trienoyl-CoA and docosa-7,10,13,16-tetraenoyl-CoA all gave Vmax. values of about 150% of that obtained with palmitoyl-CoA. The Km values obtained with these fatty acyl-CoA esters were 17 +/- 6, 13 +/- 4 and 22 +/- 3 microM respectively, which are in the same range as the value for palmitoyl-CoA (13.8 +/- 1 microM). Myristoyl-CoA gave the higher Vmax. (110% of the palmitoyl-CoA value) of the saturated fatty acyl-CoAs tested. Substrate inhibition was mostly observed with acyl-CoA esters giving Vmax. values higher than 50% of that given by palmitoyl-CoA.
Department of Physiology and Biochemistry, Dental School, University of Oslo, Norway.
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Hovik
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Osmundsen
D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D008830:Microbodies / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains
D000214:Acyl Coenzyme A; D005231:Fatty Acids, Unsaturated; D009243:NAD