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Stereochemistry of the methyl group in (R)-3-methylitaconate derived by rearrangement of 2-methylideneglutarate catalysed by a coenzyme B12-dependent mutase

Lookup NU author(s): Daniele Ciceri, Antonius Pierik, Emeritus Professor Bernard Golding

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Abstract

2-Methylideneglutarate mutase is an adenosylcobalamin (coenzyme B12)-dependent enzyme that catalyses the equilibration of 2-methylideneglutarate with (R)-3-methylitaconate. This reaction is believed to occur via protein-bound free radicals derived from substrate and product. The stereochemistry of the formation of the methyl group of 3-methylitaconate has been probed using a 'chiral methyl group'. The methyl group in 3-([2H1,3H]methyl)itaconate derived from either (R)- or (S)-2-methylidene[3-2H1,3-3H1]glutarate was a 50 : 50 mixture of (R)- and (S)-forms. It is concluded that the barrier to rotation about the C-C bond between the methylene radical centre and adjacent C-atom in the product-related radical [CH2CH(-O2CC=CH2)CO2-] is relatively low, and that the interaction of the radical with cob(1I)alamin is minimal. Hence, cob(I1)alamin is a spectator of the molecular rearrangement of the substrate radical to product radical.

Publication metadata

Author(s): Ciceri D, Pierik AJ, Hartrampf G, Broker G, Speranza G, Buckel W, Cornforth SJ, Golding BT

Publication type: Article

Publication status: Published

Journal: Helvetica Chimica Acta

Year: 2000

Volume: 83

Issue: 9

Pages: 2550-2561

ISSN (print): 0018-019X

ISSN (electronic): 1522-2675

Publisher: Verlag Helvetica Chimica Acta

URL: http://dx.doi.org/10.1002/1522-2675(20000906)83:9<2550::AID-HLCA2550>3.0.CO;2-C

DOI: 10.1002/1522-2675(20000906)83:9<2550::AID-HLCA2550>3.0.CO;2-C

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