2002 Volume 51 Issue 8 Pages 539-547
Porcine pancreatic lipase (PPL) catalyzed transesterification between tributyrylglycerol and secondary alcohols was studied at 30°C using six 2-alkanols, five 3-alkanols and differrent organic solvents with the solvent hydrophobicity (log P) ranging from -1.1 to 4.5. The plots of the enantioselectivity (as log E, E: the enantiomeric ratio) against carbon number (CN) of 2-alkanol showed the minima at CN = 8 and 9 in the solvents with log P>-0.3 and log P<-0.3, respectively. In the case of 3-alkanol, the plots showed the minima at CN = 9 in the solvents with 3.2≥log P≥2.0 and the E values increased with CN of alcohol for the other solvents. The log E values showed a rough negative correlation with log P and their correlations were different depending on the structure of alcohol. The negative correlation was rationalized by a hydrophobic interaction. Based on the above results, it was concluded that the enantioselectivity was affected by a combination of the substrate structure and the solvent hydrophobicity.