Biocatalytic Properties of Lipase from Walnut Seed (Juglans regia L.)

Abstract

AbstractLipase (E.C. 3.1.1.3) from walnut seed was purified 28.6‐fold with 31% yield using Sephadex G‐100 gel chromatography. Olive oil served as good substrate for the enzyme. The optimum pH and temperature were 9.0 and 70 °C, respectively. The lipase was stable between 30 and 80 °C for 5 min. Km and Vmax values were determined as 48 mM and 23.06 × 10−3 U/min mg for triolein as substrate. Lipase activity was slightly reduced by Cu2+, Ca2+, Hg2+, Mn2+, and Ni2+ ions, while Mg2+ and Zn2+ had no effects. Anionic surfactant sodium dodecyl sulfate stimulated lipase activity while non‐ionic surfactants Tween‐80 and Triton X‐100 had negligible effects on enzymatic activity. The enzyme activity was not affected by 50 mM urea and thioacetamide. Potassium ferricyanide, n‐bromosuccinamide and potassium cyanide reduced the enzyme activity. The enzyme showed a good stability in organic solvents, the best result being in n‐hexane (113% residual activity). The activity of dialysate was maintained approximately 80% for 1 year at −20 °C.