Microsolvation effects on the excited-state dynamics of protonated tryptophan
Microsolvation effects on the excited-state dynamics of protonated tryptophan
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DOI：
10.1021/ja065980n
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发表时间：
2006-12-27
影响因子：
15
通讯作者：
Rizzo, Thomas R.
中科院分区：
文献类型：
--
作者：
Mercier, Sebastien R.;Boyarkin, Oleg V.;Rizzo, Thomas R.
To better understand the complex photophysics of the amino acid tryptophan, which is widely used as a probe of protein structure and dynamics, we have measured electronic spectra of protonated, gas-phase tryptophan solvated with a controlled number of water molecules and cooled to similar to 10 K. We observe that, even at this temperature, the bare molecule exhibits a broad electronic spectrum, implying ultrafast, nonradiative decay of the excited state. Surprisingly, the addition of two water molecules sufficiently lengthens the excited-state lifetime that we obtain a fully vibrationally resolved electronic spectrum. Quantum chemical calculations at the RI-CC2/aug-cc-pVDZ level, together with TDDFT/pw based first-principles MD simulations of the excited-state dynamics, clearly demonstrate how interactions with water destabilize the photodissociative states and increase the excited-state lifetime.
