Evidence of Diradicals Involved in the Yeast Transketolase Catalyzed Keto-Transferring Reactions.Hsu, N.S., Wang, Y.L., Lin, K.H., Chang, C.F., Ke, S.C., Lyu, S.Y., Hsu, L.J., Li, Y.S., Chen, S.C., Wang, K.C., Li, T.L.
(2018) Chembiochem 19: 2395-2402
- PubMed: 30155962
- DOI: 10.1002/cbic.201800378
- Primary Citation of Related Structures:
- PubMed Abstract:
Transketolase (TK) catalyzes a reversible transfer of a two-carbon (C <sub>2 </sub> ) unit between phosphoketose donors and phosphoaldose acceptors, for which the group-transfer reaction that follows a one- or two-electron mechanism and the force tha ...
Transketolase (TK) catalyzes a reversible transfer of a two-carbon (C 2 ) unit between phosphoketose donors and phosphoaldose acceptors, for which the group-transfer reaction that follows a one- or two-electron mechanism and the force that breaks the C2"-C3" bond of the ketose donors remain unresolved. Herein, we report ultrahigh-resolution crystal structures of a TK (TKps) from Pichia stipitis in previously undiscovered intermediate states and support a diradical mechanism for a reversible group-transfer reaction. In conjunction with MS, NMR spectroscopy, EPR and computational analyses, it is concluded that the enzyme-catalyzed non-Kekulé diradical cofactor brings about the C2"-C3" bond cleavage/formation for the C 2 -unit transfer reaction, for which suppression of activation energy and activation and destabilization of enzymatic intermediates are facilitated.
Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan.,Biotechnology Center, National Chung Hsing University, Taichung City, 402, Taiwan.,Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, 112, Taiwan.,Department of Physics, National Dong Hwa University, Hualien, 974, Taiwan.