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- Title
Energetic feasibility of hydrogen abstraction and recombination in coenzyme B(12)-dependent diol dehydratase reaction.
- Authors
Toraya, T; Eda, M; Kamachi, T; Yoshizawa, K
- Abstract
Coenzyme B(12) serves as a cofactor for enzymatic radical reactions. The essential steps in all the coenzyme B(12)-dependent rearrangements are two hydrogen abstraction steps: hydrogen abstraction of the adenosyl radical from substrates, and hydrogen back-abstraction (recombination) of a product-derived radical from 5'-deoxyadenosine. The energetic feasibility of these hydrogen abstraction steps in the diol dehyratase reaction was examined by theoretical calculations with a protein-free, simplified model at the B3LYP/6-311G* level of density functional theory. Activation energies for the hydrogen abstraction and recombination with 1,2-propanediol as substrate are 9.0 and 15.1 kcal/mol, respectively, and essentially not affected by coordination of the substrate and the radical intermediate to K+. Since these energies can be considered to be supplied by the substrate-binding energy, the computational results with this simplified model indicate that the hydrogen abstraction and recombination in the coenzyme B(12)-dependent diol dehydratase reaction are energetically feasible.
- Publication
Journal of biochemistry, 2001, Vol 130, Issue 6, p865
- ISSN
0021-924X
- Publication type
Journal Article
- DOI
10.1093/oxfordjournals.jbchem.a003059