A chlorine isotope effect for enzyme-catalyzed chlorination.

TitleA chlorine isotope effect for enzyme-catalyzed chlorination.
Publication TypeJournal Article
Year of Publication2002
AuthorsReddy CM, Xu L, Drenzek NJ, Sturchio NC, Heraty LJ, Kimblin C, Butler A
JournalJ Am Chem Soc
Date Published2002 Dec 11
KeywordsChloride Peroxidase, Chlorine, Environmental Pollutants, Heme, Hydrocarbons, Chlorinated, Isotopes, Kinetics

Several chlorinated organic compounds (COCs) that have been detected in a wide range of human, animal, and environmental samples may be derived from natural or anthropogenic sources. To determine whether the Cl isotope ratios of these compounds could be used to differentiate sources, we investigated the chlorine isotope effect for enzyme-catalyzed chlorination. Two aromatic substrates, 1,3,5-trimethylbenzene (TMB) and 3,5-dimethylphenol (DMP), were treated with a chloroperoxidase isolated from the fungus Caldariomyces fumago. A kinetic isotope effect (KIE) (in terms of k35/k37) was calculated to be 1.012 for TMB and 1.011 for DMP. A similar reaction, but not catalyzed, with hypochlorite yielded a much smaller KIE. These results indicate that a substantial KIE exists for this process. Furthermore, natural COCs synthesized by this enzymatic pathway may have Cl isotope ratios that will be easily distinguished from anthropogenic COCs.

Alternate JournalJ. Am. Chem. Soc.
PubMed ID12465949