TAILIEUCHUNG - Báo cáo khoa học: Modeling hydration mechanisms of enzymes in nonpolar and polar organic solvents

A comprehensive study of the hydration mechanism of an enzyme in non-aqueous media was done using molecular dynamics simulations in five organic solvents with different polarities, namely, hexane, 3-pentanone, diisopropyl ether, ethanol, and acetonitrile. | ễFEBS Journal Modeling hydration mechanisms of enzymes in nonpolar and polar organic solvents Nuno M. Micaelo and Claudio M. Soares Institute de Tecnologia Quimica e Biologica Universidade Nova de Lisboa Oeiras Portugal Keywords enzyme hydration organic solvents protein modeling water clusters Correspondence C. Soares Instituto de Tecnologia Quimica e Biologica Universidade Nova de Lisboa Av. da Republica Apartado 127 2781-901 Oeiras Portugal Fax 351 21 4433644 Tel 351 21 4469610 E-mail claudio@ Website http pm Received 21 December 2006 revised 1 March 2007 accepted 8 March 2007 doi A comprehensive study of the hydration mechanism of an enzyme in nonaqueous media was done using molecular dynamics simulations in five organic solvents with different polarities namely hexane 3-pentanone diisopropyl ether ethanol and acetonitrile. In these solvents the serine protease cutinase from Fusarium solani pisi was increasingly hydrated with 12 different hydration levels ranging from 5 to 100 w w weight of water weight of protein . The ability of organic solvents to strip off water from the enzyme surface was clearly dependent on the nature of the organic solvent. The rmsd of the enzyme from the crystal structure was shown to be lower at specific hydration levels depending on the organic solvent used. It was also shown that organic solvents determine the structure and dynamics of water at the enzyme surface. Nonpolar solvents enhance the formation of large clusters of water that are tightly bound to the enzyme whereas water in polar organic solvents is fragmented in small clusters loosely bound to the enzyme surface. Ions seem to play an important role in the stabilization of exposed charged residues mainly at low hydration levels. A common feature is found for the preferential localization of water molecules at particular regions of the enzyme surface in all organic solvents water seems to be localized at equivalent .

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