Abstract
Transition state analogue (TSA) complexes formed by phosphoglycerate kinase (PGK) have been used to test the hypothesis that balancing of charge within the transition state dominates enzyme-catalyzed phosphoryl transfer. High-resolution structures of trifluoromagnesate (MgF3-) and tetrafluoroaluminate (AlF4-) complexes of PGK have been determined using X-ray crystallography and 19F-based NMR methods, revealing the nature of the catalytically relevant state of this archetypal metabolic kinase. Importantly, the side chain of K219, which coordinates the α-phosphate group in previous ground state structures, is sequestered into coordinating the metal fluoride, thereby creating a charge environment complementary to the transferring phosphoryl group. In line with the dominance of charge balance in transition state organization, the substitution K219A induces a corresponding reduction in charge in the bound aluminum fluoride species, which changes to a trifluoroaluminate (AlF30) complex. The AlF30 moiety retains the octahedral geometry observed within AlF4- TSA complexes, which endorses the proposal that some of the widely reported trigonal AlF30 complexes of phosphoryl transfer enzymes may have been misassigned and in reality contain MgF3-. © 2010 American Chemical Society.
Original language | English |
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Pages (from-to) | 6507-6516 |
Number of pages | 9 |
Journal | Journal of the American Chemical Society |
Volume | 132 |
Issue number | 18 |
DOIs | |
Publication status | Published - 12 May 2010 |