McLain Sylvia E, Soper Alan K, Terry Ann E, Watts Anthony
ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, United Kingdom.
J Phys Chem B. 2007 May 3;111(17):4568-80. doi: 10.1021/jp068340f. Epub 2007 Apr 10.
The structure and hydration of L-proline in aqueous solution have been investigated using a combination of neutron diffraction with isotopic substitution, empirical potential structure refinement modeling, and small-angle neutron scattering at three concentrations, 1:10, 1:15, and 1:20 proline/water mole ratios. In each solution the carboxylate oxygen atoms from proline accept less than two hydrogen bonds from the surrounding water solvent and the amine hydrogen atoms donate less than one hydrogen bond to the surrounding water molecules. The solute-solute radial distribution functions indicate relatively weak interactions between proline molecules, and significant clustering or aggregation of proline is absent at all these concentrations. The spatial density distributions for the hydration of the COO- group in proline show a similar shape to that found previously in L-glutamic acid in aqueous solution but with a reduced coordination number.
采用同位素取代中子衍射、经验势结构精修建模以及在脯氨酸/水摩尔比为1:10、1:15和1:20这三种浓度下的小角中子散射相结合的方法，研究了L-脯氨酸在水溶液中的结构和水合作用。在每种溶液中，脯氨酸的羧基氧原子从周围水溶剂接受的氢键少于两个，胺氢原子向周围水分子提供的氢键少于一个。溶质-溶质径向分布函数表明脯氨酸分子之间的相互作用相对较弱，在所有这些浓度下都不存在脯氨酸的显著聚集或聚合。脯氨酸中-COO⁻基团水合的空间密度分布与先前在L-谷氨酸水溶液中发现的形状相似，但配位数减少。
