Purification and Partial Characterization of Lipoxygenase from Desert Truffle (Terfezia claveryi Chatin) Ascocarps

A lipoxygenase from Terfezia claveryi Chatin ascocarp, a mycorrhizal hypogeous fungus, is described for the first time. The higher proportion of PUFA in T. claveryi ascocarps makes lipid rancidity the main factor limiting its storage life. Thus, the studies on LOX from T. claveryi are important because this enzyme, among other roles, may be involved in an alteration of lipids leading to consumer rejection. The enzyme has been purified to apparent homogeneity by phase partitioning in the presence of Triton X-114, followed by two steps of cation-exchange chromatography. The purified T. claveryi LOX preparation consisted of a single major band with an apparent molecular mass of 66 kDa after sodium dodecyl sulfate−polyacrylamide gel electrophoresis. The enzymic activity exhibited a strong specificity toward linoleic and linolenic acids as substrates, while only 32% activity was observed using γ-linolenic acid. The pH optimum of this enzyme was pH 7.0. When the enzyme reacted with linoleic acid, it produced a single peak, which comigrated with standard 13-hydroperoxy-octadecadienoic acid; 13-hydroperoxy-octadecatrienoic acid was produced during the reaction with linolenic acid.

Keywords: Ascocarp; desert truffle; mycorrhizal hypogeous fungi; lipoxygenase; Terfezia claveryi; Triton X-114; HPOD