摘要
对丙氨酸在水溶液中的构象阳动力学进行了^(13)C自旋—晶格弛豫研究.它的C_α和C_β都有完全的核奥佛好塞效应(NOE),但弛豫特性有明显差异;表明它的甲基在丙氨酸分子整体作各向同性重取向运动的同时绕C_α—C_β键快速旋转.根据这个转动扩散模型,利用实验测定的自旋—晶格弛豫时间和溶液粘度计算了丙氨酸在不同pH值下的体积.对它的体积随离子态的变化,从丙氨酸分子内和丙氨酸间以及丙氨酸与水相互作用加以讨论.此外,还得出了丙氨酸在溶液中作整体运动和甲基内旋转的势垒.以及与之结合的水分子数.
Carbon-13 NMR spin-lattice relaxation was used to investigate the comformation and dynamics of alanine in aqueous solution. It's Cα and Cβ both show a full nuclear Overhauser effect, but their relaxation behaviors are obviously different. These results indicate that the methyl group has an additional internal rotation as the whole alanine molecules makes reorientation iso-tropically in solution. Using this rotational diffusion model, molecular volumes of alanine in different pH's were then calculated from the observed spin-lattice relaxation times and solution viscosities. The variations of molecular volumes of alanine with the change of ionic forms have been discussed in terms of in-tra- and intermolecular interactions. The rotational barriers have also been estimated and found to be 20±2 kJ/mol and 14±2KJ/mol for molecular overall memoti and methyl internal rotation respectively.
出处
《生物物理学报》
CAS
CSCD
北大核心
1989年第1期1-6,共6页
Acta Biophysica Sinica
