Constructing and evaluating energy surfaces of crystalline disaccharides

被引:57
作者
French, AD
Kelterer, AM
Johnson, GP
Dowd, MK
Cramer, CJ
机构
[1] USDA ARS, So Reg Res Ctr, New Orleans, LA 70179 USA
[2] Graz Univ Technol, Inst Phys & Theoret Chem, A-8010 Graz, Austria
[3] Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA
[4] Univ Minnesota, Inst Supercomp, Minneapolis, MN 55455 USA
关键词
carbohydrate; conformation; laminarabiose; maltose; molecular mechanics; quantum mechanics; sucrose; tetrahydropyran; trehalose;
D O I
10.1016/S1093-3263(00)00041-3
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
This paper focuses on the methods used to construct Ramachandran plots for disaccharides. Our recent work based on a hybrid of molecular mechanics and quantum mechanics: energies pointed to the need to take extra care when making these maps. Care is also important in the quantitative validation of these energy surfaces with linkage conformations that were determined by crystallography. To successfully predict conformations that have been observed experimentally, the calculation of the energy should include stereo electronic effects and correctly weight the hydrogen bonding. Technical concerns include the method used to scan the range of conformations, starting geometries, and finding the zero of relative potential energy on a surface where the values were collected at regular intervals. The distributions of observed conformations on energy maps of sucrose, maltose, and laminarabiose at dielectric constants of 1.5 and 7.5 illustrate the effects of an elevated dielectric constant for the MM3 component of the hybrid energy calculations. At dielectric constants of 3.5 and 7.5, the overall average energies of observed conformations of sucrose and seven disaccharides of glucose were less than 1.0 kcal mol(-1). The distribution of corresponding energies of the various crystalline conformations conformed well to a Boltzmann-like equation. (C) 2000 by Elsevier Science Inc.
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页码:95 / 107
页数:13
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