Lipase from Brassica napus L. discriminates against cis-4 and cis-6 unsaturated fatty acids and secondary and tertiary alcohols

Lipase (EC 3.1.1.3) from oilseed rape (Brassica napus L., cv Ceres) hydrolyzes triacylglycerols containing a broad range of fatty acids at similar rates. In esterification reactions carried out in hexane, rape lipase also uses a wide range of fatty acids and alcohols as reaction partners. However, the rates of esterification of petroselinic, gamma-linolenic, stearidonic and docosahexaenoic acids are only between 2 and 7% that of oleic acid. The common feature of these fatty acids is that the first double bond is cis-4 or cis-6. Petroselaidic acid with a trans-6 double bond is esterified about 10-times faster than petroselinic acid. Arachidonic and eicosapentaenoic acids, both with the first double bond being cis-5, are esterified about 20-times faster than docosahexaenoic acid. By analogy, tripetroselinin and tri-gamma-linolenin are hydrolyzed at 14% and 1.5%, respectively, of the rate of triolein hydrolysis. The rape lipase esterifies primary alcohols but cannot esterify secondary and tertiary alcohols.