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Interconversion of (S)-glutamate and (2S,3S)-3-methylaspartate: A distinctive B-12-dependent carbon-skeleton rearrangement

Lookup NU author(s): Emeritus Professor Bernard Golding

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Abstract

The interconversion of (S)-glutamate and (2S,3S)-3-methylaspartate catalyzed by B-12-dependent glutamate mutase is discussed using results from high-level ab initio molecular orbital calculations. Evidence is presented regarding the possible role of coenzyme-B-12 in substrate activation and product formation via radical generation. Calculated electron paramagnetic resonance parameters support experimental evidence for the involvement of substrate-derived radicals and will hopefully aid the future detection of other important radical intermediates. The height of the rearrangement barrier for a fragmentation-recombination pathway, calculated with a model that includes neutral amino and carboxylic acid substituents in the migrating glycyl group, supports recent experimental evidence for the interconversion of (S)-glutamate and (2S,3S)-3-methylaspartate through such a pathway. Our calculations suggest that the enzyme may facilitate the rearrangement of (S)-glutamate through (partial) proton-transfer processes that control the protonation state of substituents in the migrating group.

Publication metadata

Author(s): Wetmore SD, Smith DM, Golding BT, Radom L

Publication type: Article

Publication status: Published

Journal: Journal of the American Chemical Society

Year: 2001

Volume: 123

Issue: 33

Pages: 7963-7972

ISSN (print): 0002-7863

ISSN (electronic): 1520-5126

Publisher: American Chemical Society

URL: http://dx.doi.org/10.1021/ja004246f

DOI: 10.1021/ja004246f

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