Kinetic Investigations with Inhibitors that Mimic the Postomolysis Intermediate in the Reactions of Coenzyme‐B12‐Dependent Glycerol Dehydratase and Diol Dehydratase
- 1 April 1997
- journal article
- Published by Wiley in European Journal of Biochemistry
- Vol. 245 (2) , 398-401
- https://doi.org/10.1111/j.1432-1033.1997.00398.x
Abstract
Kinetic investigations were performed on the coenzyme-B12-dependent glycerol dehydratase and diol dehydratase reactions using 1,2-propanediol as substrate and [omega-(adenosin-5'-O-yl)alkyl]cobalamins as mimics of the posthomolysis intermediate state of the coenzyme. All the coenzyme-B12 analogues with oligomethylene chains (C3-C7) inserted between the central Co atom and the 5' O of the adenosine moiety were competitive inhibitors with respect to coenzyme B12. The apparent inhibition constants (Ki) of the shorter-chain inhibitors, especially the C5 inhibitor, were smaller for both enzymes than those of the longer-chain (C6, C7) compounds. These results are in agreement with the expected (0.6-0.9 nm) distance between the Co and 5'-methylene paramagnetic centers in the posthomolysis intermediate state of coenzyme B12 in these reactions.Keywords
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