کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5375641 1504308 2008 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Ultrafast quenching of tryptophan fluorescence in proteins: Interresidue and intrahelical electron transfer
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Ultrafast quenching of tryptophan fluorescence in proteins: Interresidue and intrahelical electron transfer
چکیده انگلیسی
Quenching of tryptophan fluorescence in proteins has been critical to the understanding of protein dynamics and enzyme reactions using tryptophan as a molecular optical probe. We report here our systematic examinations of potential quenching residues with more than 40 proteins. With site-directed mutation, we placed tryptophan to desired positions or altered its neighboring residues to screen quenching groups among 20 amino acid residues and of peptide backbones. With femtosecond resolution, we observed the ultrafast quenching dynamics within 100 ps and identified two ultrafast quenching groups, the carbonyl- and sulfur-containing residues. The former is glutamine and glutamate residues and the later is disulfide bond and cysteine residue. The quenching by the peptide-bond carbonyl group as well as other potential residues mostly occurs in longer than 100 ps. These ultrafast quenching dynamics occur at van der Waals distances through intraprotein electron transfer with high directionality. Following optimal molecular orbital overlap, electron jumps from the benzene ring of the indole moiety in a vertical orientation to the LUMO of acceptor quenching residues. Molecular dynamics simulations were invoked to elucidate various correlations of quenching dynamics with separation distances, relative orientations, local fluctuations and reaction heterogeneity. These unique ultrafast quenching pairs, as recently found to extensively occur in high-resolution protein structures, may have significant biological implications.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Chemical Physics - Volume 350, Issues 1–3, 23 June 2008, Pages 154-164
نویسندگان
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