2,4-D Metabolism: Pathway of Degradation of Chlorocatechols by Arthrobacter sp.

Abstract

Enzymes obtained from an Arthrobacter sp. grown on 2,4-dichlorophenoxyacetic acid catalyzed the conversion of 4-chloro- and 3,5-dichlorocatechols to cis,cis-3-chloro- and cis,cis-2,4-dichloromuconic acids, respectively, by an ortho-fission mechanism. Extracts of the bacterium also converted catechol, 3- and 4-methylcatechols to the corresponding muconic acids. Upon acidification, the chlorinated cis,cis-muconic acids either rearranged to more stable isomers or lactonized with displacement of the β-chlorine atom to form 4-carboxymethylene but-2-enolide and 2-chloro-4-carboxymethylene but-2-enolide, respectively. These butenolides and the corresponding chlorinated cis,cis-muconic acids and chlorocatechols were converted enzymatically to identical products, which were tentatively identified as maleylacetic and chloromaleylacetic acids, respectively. Ring-labeled 2,4-dichlorophenoxyacetic acid was metabolized by a soluble enzyme preparation to succinic acid. © 1969, American Chemical Society. All rights reserved.