Partial Purification and Characterization of Almond Seed Lipase

Abstract

A lipase was partially purified from the almond (Amygdalus communis L.) seed by ammonium sulfate fractionation and dialysis. Kinetics of the enzyme activity versus substrate concentration showed typical lipase behavior, with K_m and V_max values of 25 mM and 113.63 µmol min⁻¹ mg⁻¹ for tributyrin as substrate. All triglycerides were efficiently hydrolyzed by the enzyme. The partially purified almond seed lipase (ASL) was stable in the pH range of 6–9.5, with an optimum pH of 8.5. The enzyme was stable between 20 and 90°C, beyond which it lost activity progresively, and exhibited an optimum temperature for the hydrolysis of soy bean oil at 65°C. Based on the temperature activity data, the activation energy for the hydrolysis of soy bean oil was calculated as −5473.6 cal/mol. Soy bean oil served as good substrate for the enzyme and hydrolytic activity was enhanced by Ca²⁺, Fe²⁺, Mn²⁺, Co²⁺, and Ba²⁺, but strongly inhibited by Mg²⁺, Cu²⁺, and Ni²⁺. The detergents, sodiumdeoxicholate and Triton X-100 strongly stimulated enzyme activity while CTAB, DTAB, and SDS were inhibitors. Triton X-405 had no effect on lipase activity. The partially purified enzyme retained its activity for more than 6 months at −20°C, beyond which it lost activity progressively.

Keywords:

• Almond seed
• Characterization
• Enzymatic activity
• Lipase
• Purification
• Stability