Production of formyl-CoA during peroxisomal alpha-oxidation of 3-methyl-branched fatty acids.

alpha-Oxidation of 3-methyl-substituted fatty acids was studied in purified rat liver peroxisomes. The experiments revealed that formyl-CoA is formed during the alpha-oxidation process. The amount of formyl-CoA found constituted 2-5% of the amount of formate formed. Under the conditions used, no activation of exogenously added formate occurred in purified peroxisomes, whereas 95.5% of added synthetic formyl-CoA was converted to formate. These data indicate that during alpha-oxidation first formyl-CoA is formed, which is then hydrolysed to formate.