嗜碱微生物胞膜外表面质子传导性质的分子机制研究

Proton transfer is a fundamental chemical process. Long-ranged and selective proton transfer is essential to many biological and chemical processes. Proton transfer rate is highly dependent on the surface properties. There for it is of great importance to such process to understand the detailed relation between surface properties and proton transfer pathways. Alkalophilic microorganisms can live in a high pH extracellular pH environment(pH 10-12). Maintaining such a reverse pH gradient (relative to the required proton flow by ATP synthase, which is from the extracellular side to the intracellular side) while keep the synthesis of ATP effectively, requires special properties of the cellular membrane. The outer surface of the membrane should be able to generate a close-to-surface proton buffer to prevent the protons being neutralized by the strongly alkali environment and should be able to transfer proton along the membrane surface rapidly to the ATP synthase sites. In this research proposal, we plan to perform molecular modeling and QHOP-MD molecular dynamics simulations to study the molecular mechanism of the formation of proton buffer near the membrane and rapid transmission of protons along the membrane surface of alkalophilic microorganisms in model systems. By studying different types of the interface: such as whether it contains titratable groups, the density and arrangement of the titratable groups, the change of surface polarizability, we would like to find the relationship of such properties with the formation of proton buffers and proton conduction efficiency (two-dimensional diffusion). Knowing such knowledge, we plan to further conduct bio-inspired design to optimize the design of the proton exchange membrane, which is of essential role in the design of new hydrogen fuel cell.

质子转移是自然界广泛存在的基本过程。其中长距离质子快速转移是很多生物和化学过程的核心组成部分。质子在不同界面的扩散效率主要依赖于界面的性质，因此界面性质的调节对质子传导的影响是长距离质子转移的关键问题。嗜碱微生物可在pH高达11－12的环境中生存，其胞膜外表面具备的特殊性质可以保障质子在胞外极端的碱性条件下快速沿胞膜运输，并沿着逆质子梯度方向回流到pH更低的胞内，而同时避免被外界碱性环境中和。其具体分子机理目前还不清楚。研究嗜碱微生物细胞膜的特殊性质对质子在其胞膜外表面扩散的机理的影响将会对仿生设计高质子传导率和高选择性的质子交换膜等研究和应用有很大的促进。我们希望通过分子建模和Q-HOP MD分子动力学模拟来研究嗜碱微生物细胞的胞膜外表面质子缓冲区的形成和质子沿膜表面快速传输通道进的分子机理和不同界面的性质对质子缓冲区和质子传导效率的影响。并以此为基础进行氢燃料电池质子交换膜的仿生设计。

质子转移是自然界广泛存在的基本过程。质子在不同界面的扩散效率主要依赖于界面的性质，因此界面性质的调节对质子传导的影响是长距离质子转移的关键问题。嗜碱微生物可在pH高达11－12的环境中生存，其胞膜外表面具备的特殊性质可以保障质子在胞外极端的碱性条件下快速沿胞膜运输，并沿着逆质子梯度方向回流到pH更低的胞内，而同时避免被外界碱性环境中和。本项目我们研究得出嗜碱微生物细胞膜的特殊性质对质子在其胞膜外表面扩散的机理有很大影响，并且这种影响将有利于仿生设计高质子传导率和高选择性的质子交换膜等。我们建立了分子建模和Q-HOP MD分子动力学模拟和研究了嗜碱微生物细胞的胞膜外表面质子缓冲区的形成和质子沿膜表面快速传输通道进的分子机理和不同界面的性质对质子缓冲区和质子传导效率的影响，进而进行了氢燃料电池质子交换膜的仿生设计。针对课题计划任务书的内容和预期目标，我们围绕研究嗜碱微生物胞膜外表面质子传导性质及半导体材料的光催化产氢方面展开一系列工作。现已发表SCI论文10篇。