Download MendeleyBiochemical and structural analysis of the mechanism for the catalysis and specificity of cellobiose 2-epimerase from Rhodothermus marinus.
Saburi, W., Muto-Fukiya, H., Jaito, N., Kato, K., Yu, J., Yao, M., Mori, H.(2025) Biosci Biotechnol Biochem 89: 973-984
- PubMed: 40121185
- DOI: https://doi.org/10.1093/bbb/zbaf042
- Primary Citation of Related Structures:
9L8I, 9L8K - PubMed Abstract:
Cellobiose 2-epimerase (CE) catalyzes C-2 epimerization of reducing end d-glucose/d-mannose residue of β-(1→4)-disaccharides, and also slightly catalyzes aldose-ketose conversion. In this study, we investigated the structure-function relationship of Rhodothermus marinus CE (RmCEs). In 2H2O, 2H replaced the 2-H of the reducing end sugar residue, suggesting a proton abstraction-addition mechanism via the cis-enediolate intermediate. The structure of the RmCE-mannobiitol complex showed that His259 was suitable for abstracting 2-H from d-mannose residue, whereas His390 was suitable for the d-glucose residue. H259A and H390A mutations abolished activity for Galβ1-4Man and Galβ1-4Glc formation from Galβ1-4Fru, respectively, and these mutants catalyzed both epimerization and isomerization to Galβ1-4Glc and Galβ1-4Man, respectively. Ala substitution of the residues interacting with the 2-O of the reducing end sugar residue significantly reduced the velocity for epimerization, but not for isomerization. Trp385, stacked onto the non-reducing-end sugar residues of disaccharides, was shown to be important for disaccharide specificity.
Organizational Affiliation:
Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan.
