Mechanism of action of adenosylcobalamin: 3-fluoro-1,2-propranediol as substrate for propanediol dehydrase--mechanistic implications.

doi:10.1021/BI00696A022

Paper

Mechanism of action of adenosylcobalamin: 3-fluoro-1,2-propranediol as substrate for propanediol dehydrase--mechanistic implications.

Published Dec 16, 1975 · R. G. Eagar, W. Bachovchin, J. Richards

Biochemistry

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16

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Abstract

3-Fluro-1,2-propanediol has been found to be a substrate for propanediol dehydrase and has very similar binding and catalytic constants compared to the natural substrate. The only isolable products of the reaction are acrolein and inorganic fluoride; with 3-fluoro-3,3-dideuterio-1,2-propanediol as substrate, only 3,3-dideuterioacrolein is obtained. These results indicate that the primary product of the reaction is 3-fluoropropionaldehyde which spontaneously loses hydrogen fluoride to yield acrolein. The similar kinetic parameters for the fluorinated as compared to the normal substrate suggest that significant charge does not develop on the fluorinated or, by implication, the natural substrate during any rate-limiting steps of the reaction. These results support a radical, as contrasted to an ionic pathway for reactions involving adenosylcobalamin and diol dehydrase.

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3-Fluro-1,2-propanediol acts as a substrate for propanediol dehydrase, yielding acrolein and inorganic fluoride, supporting a radical pathway for reactions involving adenosylcobalamin and diol

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

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Paper

Mechanism of action of adenosylcobalamin: 3-fluoro-1,2-propranediol as substrate for propanediol dehydrase--mechanistic implications.

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References

Relative enantiomer binding and reaction rates with propanediol dehydrase.

The binding site of propanediol dehydrase allows both isomers to bind, but the D()-isomer has a more favorable configuration for further reaction due to its hindered approach to the binding site.

Electron spin resonance studies with dioldehydrase. II. The hyperfine structure of proposed radical intermediates derived from isotopic substitution in 2-chloroacetaldehyde.

Electron spin resonance studies with dioldehydrase suggest hydrogen atom transfer reactions participate in catalysis by coenzyme B12 enzymes.

Cobamides and ribonucleotide reduction. XII. The electron paramagnetic resonance spectrum of "active coenzyme B12".

The EPR spectrum and spectrophotometric changes in coenzyme B12 systems are due to the formation of a cobamide intermediate in ribonucleotide reduction.

Electron spin resonance studies with dioldehydrase. Evidence for radical intermediates in reactions catalyzed by coenzyme B 12.

Dioldehydrase can catalyze the homolytic cleavage of coenzyme B12's carbon-cobalt bond, suggesting radical species may be intermediates in the catalytic reaction.

Coenzyme B 12 -dependent propanediol dehydratase systems. Ternary complex between apoenzyme, coenzyme, and substrate analog.

The ternary complex formed between propanediol dehydratase apoenzyme, coenzyme B12, and substrate analog is a stable model for the Michaelis complex, with its structure potentially slightly distorted compared to the holoenzyme and reacting holoenzyme

The mechanism of action of ethanolamine ammonia lyase, a B 12 -dependent enzyme. X. A study of the reaction by electron spin resonance spectrometry.

Ethanolamine ammonia lyase's mechanism of action involves homolysis of the carbon-cobalt bond of the coenzyme, with a narrower radical signal observed in the absence of substrate.

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