Regioselectivity and fatty acid specificity of Chromobacterium viscosum lipase

The fatty acid specificity of Chromobacterium viscosum lipase was studied by comparing the pseudo-first-order rate constants for the transesterification of different fatty acid methyl esters with 1-propanol in dry acetonitrile as solvent. It was found that this enzyme shows a significant preference towards long chain fatty acids and, for chains with the same length, towards saturated ones. The same enzyme was used to study the esterification of sorbitol and decanoic acid. A mixture of mono-, di-, tri- and tetraesters was obtained. The concentration of esters was strongly increased upon raising the temperature from 35 to 70 degrees C. The structures of the di-, tri- and tetraesters were determined using 13C NMR spectrometry. The diester appeared to be sorbitol 1,6-didecanoate, the triester was sorbitol 1,5,6-tridecanoate and the tetraester was the 1,2,5,6-tetradecanoate, which indicates that the C. viscosum lipase acylates sorbitol in a regioselective manner.