3qyo
Sensitivity of receptor internal motions to ligand binding affinity and kinetic off-rateSensitivity of receptor internal motions to ligand binding affinity and kinetic off-rate
Structural highlights
Function[DYR_ECOLI] Key enzyme in folate metabolism. Catalyzes an essential reaction for de novo glycine and purine synthesis, and for DNA precursor synthesis. Publication Abstract from PubMedSignal transduction, regulatory processes and pharmaceutical responses are highly dependent upon ligand residence times. Gaining insight into how physical factors influence residence times (1/k(off)) should enhance our ability to manipulate biological interactions. We report experiments that yield structural insight into k(off) involving a series of eight 2,4-diaminopyrimidine inhibitors of dihydrofolate reductase whose binding affinities vary by six orders of magnitude. NMR relaxation-dispersion experiments revealed a common set of residues near the binding site that undergo a concerted millisecond-timescale switching event to a previously unidentified conformation. The rate of switching from ground to excited conformations correlates exponentially with the binding affinity K(i) and k(off), suggesting that protein dynamics serves as a mechanical initiator of ligand dissociation within this series and potentially for other macromolecule-ligand systems. Although the forward rate of conformational exchange, k(conf,forward), is faster than k(off), the use of the ligand series allowed for connections to be drawn between kinetic events on different timescales. Evidence for dynamics in proteins as a mechanism for ligand dissociation.,Carroll MJ, Mauldin RV, Gromova AV, Singleton SF, Collins EJ, Lee AL Nat Chem Biol. 2012 Jan 15;8(3):246-52. doi: 10.1038/nchembio.769. PMID:22246400[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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