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The Dynamic Energy Landscape of Enzyme Catalysis
Author(s) -
Wright Peter Edwin,
Boehr David D.,
McElheny Dan,
Dyson H. Jane
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a90-a
Subject(s) - protein dynamics , dihydrofolate reductase , energy landscape , chemistry , catalytic cycle , active site , conformational isomerism , protein structure , enzyme catalysis , molecular dynamics , chemical physics , relaxation (psychology) , conformational change , reaction coordinate , conformational ensembles , computational chemistry , catalysis , stereochemistry , enzyme , biochemistry , biology , molecule , organic chemistry , neuroscience
Protein structures are not static, and molecular motions are central to their biological functions. It is essential to move beyond our largely static view of protein structure towards an understanding of the dynamics and thermodynamics of conformational changes and their relationship to protein function. NMR relaxation experiments provide a powerful approach for characterization of protein dynamics on a broad range of time scales, from ps to ms, and allow direct mapping of the protein energy landscape. Complementary insights into conformational averaging and correlated fluctuations of the protein structure are obtained by analysis of side chain rotamer populations. Recently developed relaxation dispersion experiments permit quantitative analysis of the dynamics and thermodynamics of slow conformational fluctuations in proteins and of the kinetics of protein‐ligand interactions. Applications of NMR to study the role of protein motions in the catalytic function of the enzyme dihydrofolate reductase (DHFR) will be described. Our experiments reveal active site conformational fluctuations on a time scale that is directly relevant to the structural transitions involved in progression through the catalytic cycle. Flexibility in the active site loops appears to be harnessed by the enzyme to control the flux of substrate, product, and cofactor, and to correctly position the reactants in the active site prior to the hydride transfer step. Progress through the catalytic cycle involves a dynamic energy landscape, where each intermediate populates excited states in which the protein conformation corresponds to that of the preceding or following intermediate in the cycle.