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3gtu
From Proteopedia
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| , resolution 2.8Å | |||||||
|---|---|---|---|---|---|---|---|
| Gene: | GSTM2, GSTM3 (Homo sapiens) | ||||||
| Activity: | Glutathione transferase, with EC number 2.5.1.18 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
LIGAND-FREE HETERODIMERIC HUMAN GLUTATHIONE S-TRANSFERASE M2-3 (EC 2.5.1.18), MONOCLINIC CRYSTAL FORM
Overview
The hGSTM3 subunit, which is preferentially expressed in germ-line cells, has the greatest sequence divergence among the human mu class glutathione S-transferases. To determine a structural basis for the catalytic differences between hGSTM3-3 and other mu class enzymes, chimeric proteins were designed by modular interchange of the divergent C-terminal domains of hGSTM3 and hGSTM5 subunits. Replacement of 24 residues of the C-terminal segment of either subunit produced chimeric enzymes with catalytic properties that reflected those of the wild-type enzyme from which the C-terminus had been derived. Deletion of the tripeptide C-terminal extension found only in the hGSTM3 subunit had no effect on catalysis. The crystal structure determined for a ligand-free hGSTM3 subunit indicates that an Asn212 residue of the C-terminal domain is near a hydrophobic cluster of side chains formed in part by Ile13, Leu16, Leu114, Ile115, Tyr119, Ile211, and Trp218. Accordingly, a series of point mutations were introduced into the hGSTM3 subunit, and it was indeed determined that a Y119F mutation considerably enhanced the turnover rate of the enzyme for nucleophilic aromatic substitution reactions. A more striking effect was observed for a double mutant (Y119F/N212F) which had a k(cat)/K(m)(CDNB) value of 7.6 x 10(5) s(-)(1) M(-)(1) as compared to 4.9 x 10(3) s(-)(1) M(-)(1) for the wild-type hGSTM3-3 enzyme. The presence of a polar Asn212 in place of a Phe residue found in the cognate position of other mu class glutathione S-transferases, therefore, has a marked influence on catalysis by hGSTM3-3.
About this Structure
3GTU is a Protein complex structure of sequences from Homo sapiens. Full crystallographic information is available from OCA.
Reference
An asparagine-phenylalanine substitution accounts for catalytic differences between hGSTM3-3 and other human class mu glutathione S-transferases., Patskovsky YV, Patskovska LN, Listowsky I, Biochemistry. 1999 Dec 7;38(49):16187-94. PMID:10587441
Page seeded by OCA on Thu Mar 20 19:05:08 2008
