Analogues of 1, 2-Propanediol, Inactivators of Dioldehydrase: I. Studies on the Effect of 3-Halo-1, 2-Propanediols on the Coenzyme B₁₂ Dependent Dioldehydrase Reaction. II. Studies on the Effect of an Epoxide on Dioldehydrase

Citation

Lamkin, Mark Stuart (1976) Analogues of 1, 2-Propanediol, Inactivators of Dioldehydrase: I. Studies on the Effect of 3-Halo-1, 2-Propanediols on the Coenzyme B₁₂ Dependent Dioldehydrase Reaction. II. Studies on the Effect of an Epoxide on Dioldehydrase. Master's thesis, California Institute of Technology. doi:10.7907/1E2T-TX52. https://resolver.caltech.edu/CaltechTHESIS:04052010-084939879

Abstract

PART I: 3-Chloro-1, 2 -propanediol, 3 -bromo-1, 2-propanediol, and 3-iodo-1, 2-propanediol have been found to bind to dioldehydrase. Dissociation constants are approximately equal in each case. Binding occurs in a manner similar to that of the normal substrate, 1, 2-propanediol. All three compounds behave as competitive inhibitors while 3-chloro-1, 2-propanediol and 3-brom-1, 2-propanediol inactivate the holoenzyme as well. This inactivation process is irreversible and may involve the alkylation of sulfhydryl residues of dioldehydrase. Of the above compounds, only 3-chloro-1, 2-propanediol is converted to product; possibly β-chloropropionaldehyde is formed. PART II: 2, 3-Epoxypropanol (glycidol) has been found to bind to dioldehydrase. Its calculated dissociation constant is 8.8 X 10^(-4) M. It binds to dioldehydrase even though it has but one hydroxyl group. 2, 3-Epoxypropanol behaves as a competitive inhibitor. This compound also inactivates the holoenzyme. Unlike the compounds studied in Part I, it also inactivates the apoenzyme, although at a slower rate. Since epoxides are known to alkylate sulfhydryl groups, the above result suggests the presence of exposed sulfhydryl residues.

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