Rational design of enantioselective enzymes requires considerations of entropy

• Main Authors: Ottosson, Jenny, Rotticci-Mulder, Johanna C., Rotticci, Didier, Hult, Karl
• Format: Text
• Language: English
• Published: Cold Spring Harbor Laboratory Press 2001
• Subjects: Article; Antarc*; Antarctica
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2253194; http://www.ncbi.nlm.nih.gov/pubmed/11514667

Entropy was shown to play an equally important role as enthalpy for how enantioselectivity changes when redesigning an enzyme. By studying the temperature dependence of the enantiomeric ratio E of an enantioselective enzyme, its differential activation enthalpy (ΔR-SΔH‡) and entropy (ΔR-SΔS‡) components can be determined. This was done for the resolution of 3-methyl-2-butanol catalyzed by Candida antarctica lipase B and five variants with one or two point mutations. ΔR-SΔS‡ was in all cases equally significant as ΔR-SΔH‡ to E. One variant, T103G, displayed an increase in E, the others a decrease. The altered enantioselectivities of the variants were all related to simultaneous changes in ΔR-SΔH‡ and ΔR-SΔS‡. Although the changes in ΔR-SΔH‡ and ΔR-SΔS‡ were of a compensatory nature the compensation was not perfect, thereby allowing modifications of E. Both the W104H and the T103G variants displayed larger ΔR-SΔH‡ than wild type but exhibited a decrease or increase, respectively, in E due to their different relative increase in ΔR-SΔS‡.