The influence of chemical structure on beta-oxidation by soil nocardias.

Abstract

Studies of the β-oxidation of the fatty acid side-chain of certain ω-aryl- and ω-aryloxy-n-alkylcarboxylic acids by Nocardia opaca (strain T16) and Nocardia sp. (strain P2) show that γ-phenylbutyric is more rapidly oxidized than γ-phenoxybutyric acid. The effect of the oxygen bridge is even more striking when γ-(1-naphthyl)- and γ-(1-naphthyloxy)-butyric acids are compared. The rate of β-oxidation (by strain T16) of 3-, 4-, and 2-isomers decreases in that order. This applies to monochloro- and monomethylphenoxybutyric acids and to monochlorophenoxypropionic acids. Substitution in position 2 has by far the greatest effect and chlorine exerts a bigger influence than a methyl group in all positions. The conversion of γ-(2-methyl-4-chlorophenoxy)-butyric acid (MCPB) and γ-(2:4-dichlorophenoxy)-butyric acid (2:4-DB) is very slow and proceeds only to β-hydroxy acids. On the other hand, °-(2-methyl-4-chlorophenoxy)-, °-(2:4-dichlorophenoxy)- and °-(2-chlorophenoxy)-caproic acids are relatively rapidly converted to their corresponding butyric acid derivatives. With strain T16 ω-(2-naphthyloxy)-butyric and propionic acids are more rapidly converted to their corresponding acetic acids and phenols respectively than the ω-(1-naphthyloxy) compounds. The rate of β-oxidation of γ-phenyl-, γ-(3-indolyl)- and γ-(1-naphthyl)- butyric acids (by strain P2) decreases in that order. It has been shown that β-hydroxy acid intermediates are formed from ω-aryloxybutyric acids and those from MCPB, γ-(2-methyl-4-chlorophenoxy)-crotonic and γ-(2-naphthyloxy)-butyric acids have been isolated and identified.