1MTC: Glutathione Transferase Mutant Y115f

Citation:
Abstract
Glutathione transferase rGSTM1-1 catalyzes the addition of glutathione (GSH) to 1-chloro-2,4-dinitrobenzene, a reaction in which the chemical step is 60-fold faster than the physical step of product release. The hydroxyl group of Y115, located in the active site access channel, controls the egress of product from the active site. The Y115F mutant enzyme has a k(cat) (72 s(-)(1)) that is 3.6-fold larger than that of the native enzyme (20 s(-)(1)). Crystallographic observations and evidence from amide proton exchange kinetics are consistent with localized increases in the degree of segmental motion of the Y115F mutant that are coupled to the enhanced rate of product release. The loss of hydrogen bonding interactions involving the hydroxyl group of Y115 is reflected in subtle alterations in the backbone position, an increase in B-factors for structural elements that comprise the channel to the active site, and, most dramatically, a loss of well-defined electron density near the site of mutation. The kinetics of amide proton exchange are also enhanced by a factor between 3 and 12 in these regions, providing direct, quantitative evidence for changes in local protein dynamics affecting product release. The enhanced product release rate is proposed to derive from a small shift in the equilibrium population of protein conformers that permit egress of the product from the active site.
PDB ID: 1MTCDownload
MMDB ID: 22350
PDB Deposition Date: 2002/9/20
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 1MTC: dimeric; determined by author and by software (PISA)
Molecular Components in 1MTC
Label Count Molecule
Proteins (2 molecules)
2
Glutathione S-transferase YB1(Gene symbol: Gstm1)
Molecule annotation
Chemicals (2 molecules)
1
2
* Click molecule labels to explore molecular sequence information.

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