Purification and characterization of mannose 6-phosphate reductase, a potential target for the control of Striga hermonthica and Orobanche ramosa

Abstract

Mannose 6-phosphate reductase (M6PR, EC 1.1.1.224), a potential target for the chemical control of the parasitic angiosperms that produce mannitol, was purified from the photosynthetic parasite Striga hermonthica (Del.) Benth. and the achlorophyllous parasite Orobanche ramosa L. Except for the K_m values for NADPH, most of the characteristics of the enzymes are similar in these species, i.e. a monomeric structure of 38–39 kDa molecular mass, a pH optimum of 7.0–7.5 suggesting a cytosolic location, a relatively high optimum temperature (35–45˚C), a low K_m value for mannose 6-phosphate of 5.9–8.6 mM and, lastly, a significant preference for NADPH as nucleotidic cofactor.