title: Size as a parameter for solvent effects on Candida antarctica lipase B enantioselectivity.
abstract: Changes in solvent type were shown to yield significant improvement of enzyme enantioselectivity. The resolution of 3-methyl-2-butanol catalyzed by Candida antarctica lipase B, CALB, was studied in eight liquid organic solvents and supercritical carbon dioxide, SCCO(2). Studies of the temperature dependence of the enantiomeric ratio allowed determination of the enthalpic (Delta(R-S)Delta H(++)) as well as the entropic (Delta(R-S)Delta S(++)) contribution to the overall enantioselectivity (Delta(R-S)Delta G(++)= -RTlnE). A correlation of the enantiomeric ratio, E, to the van der Waals volume of the solvent molecules was observed and suggested as one of the parameters that govern solvent effects on enzyme catalysis. An enthalpy-entropy compensation relationship was indicated between the studied liquid solvents. The enzymatic mechanism must be of a somewhat different nature in SCCO(2), as this reaction in this medium did not follow the enthalpy-entropy compensation relation.
authors.affiliation: Department of Biotechnology, Royal Institute of Technology, Stockholm Center for Physics Astronomy and Biotechnology, Sweden.
authors.forename: Jenny
authors.initials: J
authors.lastname: Ottosson
authors.forename: Linda
authors.initials: L
authors.lastname: Fransson
authors.forename: Jerry W
authors.initials: JW
authors.lastname: King
authors.forename: Karl
authors.initials: K
authors.lastname: Hult
mesh_terms: D002175:Candida / Q000201:enzymology*; D002384:Catalysis; D005656:Fungal Proteins; D008049:Lipase / Q000737:chemistry; D008970:Molecular Weight; D000439:Pentanols / Q000737:chemistry; D012997:Solvents / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D005656:Fungal Proteins; D000439:Pentanols; D012997:Solvents; D008049:Lipase; C431349:lipase B, Candida antarctica