Effect of organic solvent on the crystal structure of Concanavalin A

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Effect of organic solvent on the crystal structure of Concanavalin A

The cross-linked crystals of Concanavalin A were soaked in water and in anhydrous acetonitrile as well as were re-soaked in water after soaking in acetonitrile. Their structures were determined by X-ray crystallography and compared with the uncross-linked native structure. One of them, which was soaked in net acetonitrile, underwent considerable changes in the diffraction pattern when soaked in net acetonitrile. Its cell parameters are 0.45 and 0. 57 nm shorter ina axis and inb axis, but 0.12 nm longer inc axis than those of the native, respectively. It was found that acetonitrile has an effect on the conformation of poly peptide chain in the flexible turn and loop regions, except for β-sheets. The confornation of cross-linked structure in soaked acetonitrile may recorvered to the native when re-soaked in water, and its conserved acetonitrile molecule is used as a probe to exploit the regions of protein surface with specificity and affinity. Project supported by the Youth Grants of Peking University and Grants for Return-scholars of State Education Commission of China and also supported by the Grants for “the important chemical problems in life process”