Fish Oil Research Today is a free monthly online journal that collates and summarizes the latest research about Fish Oil, including details on omega-3, dosage, health benefits, diet.

Identification of two novel microalgal enzymes involved in the conversion of the omega3-fatty acid, eicosapentaenoic acid, into docosahexaenoic acid.

Pereira SL, Leonard AE, Huang YS, Chuang LT, Mukerji P

Department of Strategic Research, Ross Products Division-Abbott Laboratories, 3300 Stelzer Road, Columbus, OH 43219, USA. suzette.pereira@abbott.com

Marine microalgae such as Pavlova and Isochrysis produce abundant amounts of the omega3-PUFAs (polyunsaturated fatty acids), EPA (eicosapentaenoic acid, 20:5n-3) and DHA (docosahexaenoic acid, 22:6n-3). The pathway leading to the conversion of EPA into DHA in these lower eukaryotes is not well established although it is predicted to involve an elongation step, catalysed by an elongating enzyme complex, leading to the conversion of EPA into omega3-DPA (omega-3-docosapentaenoic acid, 22:5n-3); followed by a desaturation step, catalysed by a Delta4-desaturase, which results in the conversion of DPA into DHA. To date, the enzymes involved in the elongation of EPA have not been identified from any lower eukaryote. In the present study, we describe the identification of microalgal genes involved in the two-step conversion of EPA into DHA. By expressed sequence tag analysis, a gene (pavELO) encoding a novel elongase was identified from Pavlova, which catalysed the conversion of EPA into omega3-DPA in yeast. Unlike any previously identified elongase from higher or lower eukaryotes, this enzyme displayed unique substrate specificity for both n-6 and n-3 C20-PUFA substrates, with no activity towards any C18- or C22-PUFA substrates. In addition, a novel Delta4-desaturase gene (IgD4) was isolated from Isochrysis, which was capable of converting omega3-DPA into DHA, as well as adrenic acid (22:4n-6) into omega6-DPA. Yeast co-expression studies, with pavELO and IgD4, revealed that these genes were capable of functioning together to carry out the two-step conversion of EPA into DHA.

Published 19 November 2004 in Biochem J, 384: 357-66.
Full-text of this article is available online (may require subscription).

© 2004-2008 Fish Oil Research Today. All Rights Reserved.