Biochemical characterization of phosphatase,  -galactosidase and  -mannosidase activities of seeds of an oleaginous cucurbit: Lagenaria siceraria (Molina) Standl blocky-fruited cultivar

Abstract

Seeds extract of Lagenaria siceraria (Molina) Standl (blocky-fruited cultivar) was screened for enzymatic hydrolytic activities over synthetic variety and natural substrates. The best hydrolytic activities mainly consisted of phosphatase (0.68 ± 0.02 UI/mg), β-galactosidase (0.26 ± 0.03 UI/mg) and α -mannosidase (0.17 ± 0.02 UI/mg). Physicochemical
characterization showed that these enzymatic activities were maximal at 55°C in sodium acetate buffer (pHs 4.6 and 5.6). They showed pH and temperature stability and appeared to be resistant in the presence of 5 mM cations (Na+, K+, Ca2+, Ba2+ and Mg2+) concentration and 1% (w/v) detergents (cationic, non-ionic and anionic). The phosphatase activity on different phosphorylated substrates showed it ability to hydrolyze greatly para-nitrophenylphosphate (100 ± 2.3%) and ATP (95.3 ± 2.6%) and in lesser extent sodium phytate (15.2 ± 1.8%). As for natural substrates as lactose and the three different mannobioses linked (α -1,2; α -1,3 α -1,6), that were significantly hydrolyzed by β-galactosidase and α -mannosidase activity respectively. These interesting characteristics deserved to be deeply investigated for the valorisation of Lagenaria siceraria seeds phosphatase, β -galactosidase and α -mannosidase in potential biotechnological applications.

Key words: Oleaginous cucurbit, Lagenaria siceraria, blocky-fruited cultivar, seeds, phosphatase activity, β -galactosidase activity, α -mannosidase activity.