Enamine is a well-known reactive intermediate mediating essential thiamine-dependent catalysis in central metabolic pathways. However, this intermediate is not found in the thiamine-dependent catalysis of the vitamin K biosynthetic enzyme MenD. Instead, an active tetrahedral post-decarboxylation intermediate is stably formed in the enzyme and was structurally determined at 1 ...
Enamine is a well-known reactive intermediate mediating essential thiamine-dependent catalysis in central metabolic pathways. However, this intermediate is not found in the thiamine-dependent catalysis of the vitamin K biosynthetic enzyme MenD. Instead, an active tetrahedral post-decarboxylation intermediate is stably formed in the enzyme and was structurally determined at 1.34 Å resolution in crystal. This intermediate takes a unique conformation that allows only one proton between its tetrahedral reaction center and the exo-ring nitrogen atom of the aminopyrimidine moiety in the cofactor with a short distance of 3.0 Å. It is readily convertible to the final product of the enzymic reaction with a solvent-exchangeable proton at its reaction center. These results show that the thiamine-dependent enzyme utilizes a tetrahedral intermediate in a mechanism distinct from the enamine catalytic chemistry.
Organizational Affiliation:
Department of Chemistry, ‡State Key Laboratory for Molecular Neuroscience, and §Environmental Science Program, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong SAR, China.
AD [auth G], BB [auth C], BC [auth E], CB [auth C], LC [auth F],
AD [auth G], BB [auth C], BC [auth E], CB [auth C], LC [auth F], LD [auth H], MC [auth F], N [auth A], NA [auth C], OB [auth D], OD [auth H], R [auth A], S [auth A], T [auth A], TA [auth C], U [auth A], V [auth A], W [auth A], WA [auth C], XA [auth C], XC [auth G]
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