Slow solvation dynamics at the active site of an enzyme: Implications for catalysis

被引:72
作者
Guha, S
Sahu, K
Roy, D
Mondal, SK
Roy, S
Bhattacharyya, K
机构
[1] Bose Inst, Dept Biophys, Kolkata 700054, W Bengal, India
[2] Indian Assoc Cultivat Sci, Dept Chem Phys, Kolkata 700032, W Bengal, India
[3] Indian Inst Chem Biol, Kolkata 700032, W Bengal, India
关键词
D O I
10.1021/bi0473915
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Solvation dynamics at the active site of an enzyme, glutaminyl-tRNA synthetase (GlnRS), was studied using a fluorescence probe, acrylodan, site-specifically attached at cysteine residue C229, near the active site. The picosecond time-dependent fluorescence Stokes shift indicates slow solvation dynamics at the active site of the enzyme, in the absence of any substrate. The solvation dynamics becomes still slower when the substrate (glutamine or tRNA(Gln)) binds to the enzyme. A mutant Y211H-GlnRS was constructed in which the glutamine binding site is disrupted. The mutant Y211H-GlnRS labeled at C229 with acrylodan exhibited significantly different solvent relaxation, thus demonstrating that the slow dynamics is indeed associated with the active site. Implications for catalysis and specificity have been discussed.
引用
收藏
页码:8940 / 8947
页数:8
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