Esterification in non-aqueous solvents: cholesterol esterase as a selective biocatalysator from porcine pancreas

From commercial porcine pancreas extract (pancreatin, PPE) an enzyme (60 kDa) was isolated and purified to SDS-PAGE homogeneity by combined ammonium sulphate fractionation, hydrophobic interaction chromatography and gel permeation chromatography. Isoelectric focusing of the purified enzyme revealed several bands at pH 4.5-5.0 and at pH 6.5-8.0. The analysis of 20 N-terminal amino acids led to its identification as cholesterol esterase (EC 3.1.1.13). While lipase (PPL), also isolated and purified from PPE, did not show esterifying activity in organic solvent, cholesterol esterase catalysed the selective esterification of 2-pentanol with butanoic acid in heptane.