Molecular Cloning and Characterization of Glucose-6-phosphate dehydrogenase from Brugia malayi

Abstract

Glucose 6-phosphate dehydrogenase (G6PD) a regulatory enzyme of pentose phosphate pathway from Brugia malayi was cloned, expressed and biochemically characterised. The Km values for glucose 6-phosphate and NADP were 0.25 mM and 0.014mM respectively. The rBmG6PD exhibited optimum pH of 8.5 and temperature, 40°C. ATP--S, ATP-β,-NH, ADP-β-S, Na+, K+, Li+ and, Cu++ ions were found to be strong inhibitors of rBmG6PD. The rBmG6PD, a tetramer with subunit molecular weight of 75 kDa contains 0.02 mol of SH group per mol of monomer. Blocking of SH group with SH-inhibitors, leads to activation of rBmG6PD activity by N-ethylmaleimide. CD analysis indicated that rBmG6PD is composed of 37% α-helices and 26% β-sheets. The unfolding equilibrium of rBmG6PD with GdmCl/urea showed the triphasic unfolding pattern along with the highly stable intermediate obtained by GdmCl.