Sampling the protonation states: the pH-dependent UV absorption spectrum of a polypeptide dyad.
Sampling the protonation states: the pH-dependent UV absorption spectrum of a polypeptide dyad.
复制标题
DOI：
10.1039/c8cp03557a
复制
发表时间：
2017-10
期刊：
影响因子：
--
通讯作者：
Elisa Pieri;V. Ledentu;Miquel Huix-Rotllant;N. Ferré
中科院分区：
文献类型：
--
作者：
Elisa Pieri;V. Ledentu;Miquel Huix-Rotllant;N. Ferré
当一个发色团与几个可滴定的分子位点相互作用时，其光物理性质的建模需要考虑到所有可能的质子化状态。我们开发了一种多尺度方案，基于恒定ph值的分子动力学模拟和QM/MM激发能计算，旨在采样具有酪氨酸-色氨酸二偶体与两个天冬氨酸残基相互作用的短多肽的相空间和质子化状态空间。我们表明，这样的方案是准确的，足以帮助解释实验酪氨酸在酸性和碱性的紫外吸收光谱。此外，它被证实，自由基色氨酸可能有助于肽谱，由于紫外线诱导的电子转移从酪氨酸到色氨酸，最终揭示了肽谱的复杂的ph依赖行为。
When a chromophore interacts with several titratable molecular sites, the modeling of its photophysical properties requires to take into account all their possible protonation states. We have developed a multi-scale protocol, based on constant-pH molecular dynamics simulations coupled to QM/MM excitation energy calculations, aimed at sampling both the phase space and protonation state space of a short polypeptide featuring a tyrosine-tryptophan dyad interacting with two aspartic acid residues. We show that such a protocol is accurate enough to help in the interpretation of the experimental tyrosine UV absorption spectrum at both acidic and basic pH. Moreover, it is confirmed that radical tryptophan probably contributes to the peptide spectrum, thanks to a UV-induced electron transfer from tyrosine to tryptophan, ultimately shedding light on the complex pH-dependent behavior of the peptide spectrum.