Xu F, Cross T A
Department of Chemistry, Institute of Molecular Biophysics, and The National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32306, USA.
Proc Natl Acad Sci U S A. 1999 Aug 3;96(16):9057-61. doi: 10.1073/pnas.96.16.9057.
Polypeptide conformer interconversion in a low dielectric environment is shown to be highly dependent on water concentration. Water increases this rate by 10(3), apparently by catalyzing hydrogen bond exchange, and thereby presenting functional properties analogous to that of a foldase. This catalytic effect is demonstrated on the interconversion of a parallel gramicidin dimer into an antiparallel dimer. A Hill coefficient of 6.5 is observed, illustrating the highly cooperative nature of the process. Protein folding in nonpolar environs, such as the hydrophobic core of a protein or the hydrophobic domain of a lipid bilayer, may be contingent on and rate-limited by the scarcity of water.
研究表明，在低介电环境中多肽构象异构体的相互转化高度依赖于水的浓度。水使该速率提高了10³，显然是通过催化氢键交换，从而呈现出类似于折叠酶的功能特性。这种催化作用在平行短杆菌肽二聚体向反平行二聚体的相互转化中得到了证明。观察到的希尔系数为6.5，说明了该过程具有高度协同性。在非极性环境中，如蛋白质的疏水核心或脂质双层的疏水结构域中的蛋白质折叠，可能取决于水的稀缺并受其限制。
