Biochemical Characterization of Two Acid Phosphatases Purified from Edible Seeds of the Neglected Crop Lagenaria siceraria (Molina) Standl. Blocky-Fruited Cultivar

Seeds of an under-researched crop, Lagenaria siceraria (Molina) Standl., largely cultivated and prized in sub-Saharan Africa, were analyzed for their enzymatic potentials. Investigations led to the purification of two acid phosphatases (EC 3.1.3.2) from the blocky-fruited cultivar. The purification procedure consisted of ammonium sulphate fractionation, ion-exchange, size exclusion and hydrophobic interaction chromatography. The enzymes designated BLsAP1 and BLsAP2 had native molecular weights of approximately 61 and 36 kDa, respectively, and functioned as dimeric (BLsAP1) and monomeric (BLsAP2) structures. The two isoforms isolated had a similar optimum pH (5.6) and temperature (60 C), and remained fully active in the presence of most detergents as well as ethylene diamine tetraacetic acid (EDTA), Ca2+ and Mg2+. Substrate specificity revealed that the two acid phosphatases hydrolyzed a broad range of phosphorylated substrates mainly consisting of natural substrates such as adenosine-5'-triphosphate (ATP), adenosine-5'-diphosphate (ADP) and pyrophosphate. Moreover, BLsAP1 exhibited a significant phytase activity. These findings suggest that the two acid phosphatases may play a key role in metabolic processes and in reducing the amount of phytate, an antinutritional substance contained in this plant seed. Consequently, the purified enzymes can find potential applications in food industries.