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Functional nonequivalence of transketolase active centers
Author(s) -
Kochetov German A.,
Sevostyanova Irina A.
Publication year - 2010
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1002/iub.395
Subject(s) - transketolase , pentose phosphate pathway , enzyme , pentose , active site , biochemistry , thiamine , thiamine pyrophosphate , chemistry , cofactor , sugar phosphates , nucleotide salvage , nucleotide , stereochemistry , metabolic pathway , transaldolase , ribose , glycolysis , fermentation , gene
Transketolase (TK, EC 2.2.1.1), the key enzyme of the non‐oxidative branch of pentose phosphate pathway of hydrocarbon transformation, plays an important role in a system of substrate rearrangement between pentose shunt and glycolysis, acting as a reversible link between the two metabolic pathways. In addition, it supplies precursors for biosyntheses of nucleotides, aromatic amino acids, and vitamins. In plants, the enzyme plays a central role in the Calvin cycle. TK catalyzes interconversion of sugar phosphates. Thiamine diphosphate (TDP) and bivalent cations serve as its cofactors. Being a typical TDP‐dependent enzyme, TK is the least complex representative of this group of enzymes, and this accounts for its use as a model in studies of their structure and mechanism of action. TK is readily crystallized, this being the reason why the first crystal X‐ray structure analysis of TDP‐dependent enzymes was performed with a TK sample. Both the general structure of TK and the structures of its active centers have been studied in detail. In this article, we review experimental evidence of functional nonequivalence of the two active centers of TK, which are known to be identical by crystal X‐ray structure analysis. © IUBMB IUBMB Life, 62(11): 797–802, 2010.