Wachlmayr Johann, Fläschner Gotthold, Pluhackova Kristyna, Sandtner Walter, Siligan Christine, Horner Andreas
Institute of Biophysics, Johannes Kepler University Linz, Linz, Austria.
Department of Biosystems Science and Engineering, Eidgenössiche Technische Hochschule (ETH) Zürich, Basel, Switzerland.
Commun Chem. 2023 Jun 29;6(1):135. doi: 10.1038/s42004-023-00919-0.
Facilitated water permeation through narrow biological channels is fundamental for all forms of life. Despite its significance in health and disease as well as for biotechnological applications, the energetics of water permeation are still elusive. Gibbs free energy of activation is composed of an enthalpic and an entropic component. Whereas the enthalpic contribution is readily accessible via temperature dependent water permeability measurements, estimation of the entropic contribution requires information on the temperature dependence of the rate of water permeation. Here, we estimate, by means of accurate activation energy measurements of water permeation through Aquaporin-1 and by determining the accurate single channel permeability, the entropic barrier of water permeation through a narrow biological channel. Thereby the calculated value for [Formula: see text] = 2.01 ± 0.82 J/(mol·K) links the activation energy of 3.75 ± 0.16 kcal/mol with its efficient water conduction rate of ~10 water molecules/second. This is a first step in understanding the energetic contributions in various biological and artificial channels exhibiting vastly different pore geometries.
水通过狭窄生物通道的易化渗透对所有生命形式而言都是至关重要的。尽管其在健康与疾病以及生物技术应用方面具有重要意义，但水渗透的能量学仍然难以捉摸。活化吉布斯自由能由焓分量和熵分量组成。虽然焓贡献可通过与温度相关的水渗透率测量轻易获得，但熵贡献的估计需要有关水渗透速率的温度依赖性的信息。在此，我们通过对水通过水通道蛋白-1的渗透进行精确的活化能测量，并通过确定精确的单通道渗透率，来估计水通过狭窄生物通道的渗透的熵垒。由此计算得出的[公式：见正文]值为2.01±0.82 J/(mol·K)，将3.75±0.16 kcal/mol的活化能与其约10个水分子/秒的高效水传导速率联系起来。这是理解在具有截然不同孔隙几何形状的各种生物和人工通道中的能量贡献的第一步。
