Purification and characterization of a digestive lipase in the midgut of Ectomyelois ceratoniae Zeller (Lepidoptera: Pyralidae)

Abstract

Ectomyelois ceratoniae is one of the key constraints in the production of pomegranate and pistachio in Iran. Since there is little knowledge on digestive lipases of insects, the current study aimed to purify and characterize the enzyme in the midgut of E. ceratoniae. Purification by ammonium sulfate, Sephacryl G-100 and Di-ethyl-amino-ethanol (DEAE)–cellulose fast flow revealed an enzyme with a specific activity of 0.4 U mg–1 protein, 29.62 of recovery, 28.57 of purification fold and 25 kDa of molecular weight. The purified lipase showed the highest activities at pH 7 and a temperature of 30°C. The enzyme was stable for 3 h at 30°C. Different concentrations of phenylmethylsulfonyl fluoride (PMSF) and ethylenediaminetetraacetic acid (EDTA) were used to find possible inhibition of the purified lipase. It was observed that different concentrations of EDTA had no inhibitory effects but different concentrations of PMSF significantly decreased activity of the purified lipase. Since long chain unsaturated fatty acids are essential dietary components, inhibition of digestive lipases may cause severe reduction in growth and development of insects. Hence, study of the biochemical properties of insect digestive lipases is necessary to consider their inhibitions in plant breeding programs as a component of integrated pest management.