Specificity of papaya lipase in esterification of aliphatic alcohols - A comparison with microbial lipases

Straight-chain saturated C4 to C18 alcohols and unsaturated C18 alcohols, such as cis-9-octadecenyl (oleyl), cis-6-octadecenyl (petroselinyl), cis-9,cis-12-octadecadienyl (linoleyl), all-cis-9,12, 15-octadecalrienyl (alpha -linolenyl), and all-cis-6, 9,12-octadecatrienyl (gamma -linolenyl) alcohols, were esterified with caprylic acid using papaya (Carica papaya) latex lipase (CPL) and immobilized lipases from Candida antarctica (Lipase B, Novozym, NOV) and Rhizomucor miehei (Lipozyme, LIP) as biocalalysts. With CPL, highest activity was found for octyl and decyl caprylate syntheses, whereas both NOV and LIP showed a broad chain-length specificity toward the alcohol substrates. CPL strongly discriminated against all C18 alcohols studied, relative to n-hexanol, whereas the microbial lipases accepted the C18 alcohols as substrates nearly as well as n-hexanol. Both petroselinyl and gamma -linolenyl alcohol were very well accepted as substrates by NOV as well as LIP, although the corresponding fatty acids, i.e., petroselinic and gamma -linolenic acid, are strongly discriminated against by several microbial and plant lipases, including LIP and CPL.