Obtaining higher transesterification rates with subtilisin Carlsberg in nonaqueous media

Three phase partitioning (protein precipitate obtained as an interfacial layer between lower aqueous and upper t-butanol phases, formed by the addition of ammonium sulphate and t-butanol to the aqueous solution of protein) followed by lyophilization in the presence of two-component excipient resulted in 400–480× increases in transesterification activity of lyophilized powders of subtilisin Carlsberg, depending on the solvent. The three phase partitioned enzyme, ‘dried’ by washing with butanol, gave 3–4× higher rates (depending on the solvent used) than the enzyme preparation dried by lyophilization in the presence of two-component excipient system.