Probing the Internal Dynamics and Shape of Simple Peptides in Urea, Guanidinium Hydrochloride, and Proline Solutions with Time-Resolved Fluorescence Anisotropy and Atomistic Cosolvent Simulations
Probing the Internal Dynamics and Shape of Simple Peptides in Urea, Guanidinium Hydrochloride, and Proline Solutions with Time-Resolved Fluorescence Anisotropy and Atomistic Cosolvent Simulations
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利用时间分辨荧光各向异性和原子共溶剂模拟探测尿素、盐酸胍和脯氨酸溶液中简单肽的内部动力学和形状
DOI：
10.1021/acs.jpcb.1c06838
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Kuczera, Krzysztof
中科院分区：
文献类型：
--
作者：
Jas, Gouri S.;Childs, Ed W.;Middaugh, C. Russell;Kuczera, Krzysztof
利用皮秒时间分辨荧光各向异性测量变性剂和渗透剂对最简单二肽重定向动力学的影响。溶剂变性剂盐酸胍（gdm）、尿素和渗透物脯氨酸在不同浓度下使用。在固定温度下对变性剂浓度依赖性的分析表明，在几乎相同的溶剂粘度（η）下，两种不同的变性剂的重定向时间更快和更慢。在pH值为7.2时，在高摩擦极限下，胍和尿素的重定向时间τ分别为r≈0.4和r≈0.6，明显偏离Kramers理论（τ∝η1）。在脯氨酸中，τ几乎与η成正比。二肽在相同共溶剂中的原子分子动力学模拟与测量的旋转取向时间非常吻合。二肽二面体（φ, ψ）在水和6 M尿素中的异构化时间几乎相同，在胍中的异构化时间明显较慢。如果更快和更慢的重定向时间可以与致密和膨胀的形状相关联，那么胍和尿素的分数粘度依赖性可能是由于这些共溶剂中多肽的内部动力学涉及动态元件内部摩擦的高低。
Picosecond time-resolved fluorescence anisotropy was used to measure the effect of denaturants and osmolytes on the reorientation dynamics of the simplest dipeptide. The solvent denaturants guanidinium hydrochloride (gdm), urea, and the osmolyte proline were used at several concentrations. Analysis of the concentration dependence of denaturants at a fixed temperature showed faster and slower reorientation time in two different denaturants at a nearly identical solvent viscosity (η). The reorientation time τ significantly deviates from Kramers’ theory (τ ∝ η1) in the high friction limit for guanidinium and urea withr≈ 0.4 andr≈ 0.6 at pH 7.2, respectively. In proline, τ is nearly proportional to η. Atomistic molecular dynamics simulations of the dipeptide in identical cosolvents showed excellent agreement with the measured rotational orientation time. The dipeptide dihedral (ϕ, ψ) isomerization times in water and 6 M urea are almost identical and significantly slower in guanidinium. If a faster and slower reorientation time can be associated with the compact and expanded shapes, the fractional viscosity dependence for guanidinium and urea may result from the fact that internal dynamics of peptides in these cosolvents involve higher and lower internal friction within the dynamic elements.