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. 1980 Jan;77(1):333–337. doi: 10.1073/pnas.77.1.333

Carboxybiotin translocation mechanisms suggested by diffraction studies of biotin and its vitamers.

G T DeTitta, R Parthasarathy, R H Blessing, W Stallings
PMCID: PMC348264  PMID: 6928626

Abstract

Biotin is a coenzyme that fixes CO2 for transfer in a family of carboxylase, decarboxylase, and transcarboxylase enzymes. Their enzyme reactions involve two basic steps during which a carboxybiotinyl intermediate forms at one site and translocates to a second (distinct) site for CO2 transfer. Our diffraction studies of biotin and its vitamers suggest that translocation involves rotation about one, or at most two, bonds in biotin's valeryl chain. The rotations are energetically economical gauche in equilibrium trans rotations about the two valeryl bonds nearest the biotin bicyclic ring. They move a carbon atom of a CO2 moiety bound at N-1' approximately 7 A, a distance in accord with spectroscopic measurements of one of the biotin enzymes. From our studies we infer that sulfur in biotin imparts to the valeryl chain a conformational variability necessary for bond rotation and, hence, translocation between catalytic sites.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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