Premium
Hydrostatic Pressure Studies Distinguish Global from Local Protein Motions in C−H Activation by Soybean Lipoxygenase‐1
Author(s) -
Hu Shenshen,
CattinOrtolá Jérôme,
Munos Jeffrey W.,
Klinman Judith P.
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201603592
Subject(s) - chemistry , hydrostatic pressure , kinetic isotope effect , protein dynamics , kinetic energy , bar (unit) , reaction rate constant , kinetics , stereochemistry , molecular dynamics , computational chemistry , thermodynamics , deuterium , atomic physics , physics , quantum mechanics , meteorology
The proposed contributions of distinct classes of local versus global protein motions during enzymatic bond making/breaking processes has been difficult to verify. We employed soybean lipoxygenase‐1 as a model system to investigate the impact of high pressure at variable temperatures on the hydrogen‐tunneling properties of the wild‐type protein and three single‐site mutants. For all variants, pressure dramatically elevates the enthalpies of activation for the C−H activation. In contrast, the primary kinetic isotope effects (KIEs) for C−H activation and their corresponding temperature dependencies remain unchanged up to ca. 700 bar. The differential impact of elevated hydrostatic pressure on the temperature dependencies of rate constants versus substrate KIEs provides direct evidence for two distinct classes of protein motions: local, isotope‐dependent donor–acceptor distance‐sampling modes, and a more global, isotope‐independent search for productive protein conformational sub‐states.