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Demethylation and degradation of phenylmethylethers by the sulfide-methylating homoacetogenic bacterium strain TMBS 4

Demethylation and degradation of phenylmethylethers by the sulfide-methylating homoacetogenic bacterium strain TMBS 4

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KREFT, Jan-Ulrich, Bernhard SCHINK, 1993. Demethylation and degradation of phenylmethylethers by the sulfide-methylating homoacetogenic bacterium strain TMBS 4. In: Archives of Microbiology. 159(4), pp. 308-315. ISSN 0302-8933. eISSN 1432-072X

@article{Kreft1993Demet-6527, title={Demethylation and degradation of phenylmethylethers by the sulfide-methylating homoacetogenic bacterium strain TMBS 4}, year={1993}, number={4}, volume={159}, issn={0302-8933}, journal={Archives of Microbiology}, pages={308--315}, author={Kreft, Jan-Ulrich and Schink, Bernhard} }

Biochemical studies on anaerobic phenylmethylether cleavage by homoacetogenic bacteria have been hampered so far by the complexity of the reaction chain involving methyl transfer to acetyl-CoA synthase and subsequent methyl group carbonylation to acetyl-CoA. Strain TMBS 4 differs from other demethylating homoacetogenic bacteria in using sulfide as a methyl acceptor, thereby forming methanethiol and dimethylsulfide. Growing and resting cells of strain TMBS 4 used alternatitively CO 2 as a precursor of the methyl acceptor CO for homoacetogenic acetate formation. Demethylation was inhibited by propyl iodide and reactivated by light, indicating involvement of a corrinoid-dependent ethyltransferase. Strain TMBS 4 contained ca. 750 nmol g dry mass - 1 of a corrinoid tentatively identified as 5-hydroxybenzimidazolyl cobamide. A photometric assay for measuring the demethylation activity in cell extracts was developed based on the formation of a yellow complex of Ti 3 § with 5-hydroxyvanillate produced from syringate by demethylation. In cell extracts, the methyltransfer reaction from methoxylated aromatic compounds to sulfide or methanethiol depended on reductive activation by Ti 3 +. ATP and Mg 2 + together greatly stimulated this reductive activation without being necessary for the demethylation reaction itself. The specific activity of the transmethylating enzyme system increased proportionally with protein concentration up to 3 mg ml- 1 reaching a constant level of 20 nmol min -a mg -1 at protein concentrations > 10 mg ml- 1. The specific rate of activation increased in a non-linear manner with protein concentration. Strain TMBS 4 degraded gallate, the product of sequential demethylations, to 3 acetate through the phloroglucinol pathway as found earlier with Pelobacter acidigallici. Schink, Bernhard First publ. in: Archives of Microbiology 159 (1993), 4, pp. 308-315 1993 2011-03-24T17:27:10Z Kreft, Jan-Ulrich eng Schink, Bernhard Kreft, Jan-Ulrich application/pdf 2011-03-24T17:27:10Z deposit-license Demethylation and degradation of phenylmethylethers by the sulfide-methylating homoacetogenic bacterium strain TMBS 4

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