By affinity chromatography, germins G and ψG were purified from roots of wheat seedling and wheat embryos imbibition for 4 h (Table1). Characterization of the germins G and ψGwere studied.Theresults showed that Gand ψG were stable at temperatures lower than 60℃ (Fig.4), and had an optimum pH at 3.5 (Fig.1). The Km value of G for oxalate was 0.084 mmol/ L, while that of ψG was 0.053 mmol/L (Fig.3). Oxalate showed substrate inhibition effect above 0.2 mmol/Lon G and ψG (Fig.2). EDTA, NH4 , + Mn2+, Mg2+, Na+ and K+ at a concentration of 0.1 mmol/L had no effect on OxO activity. CO3 , NO3 and SO4 2- - 2- at a concentration of 0.1 mmol/L inhibited partially the activities of G and ψG, 0.1mmol/L Cu2+, Fe2+, Al3+ completely in- hibited the activities of G and ψG, but addition of 0.1 mmol/L EDTA partially relieved the inhibition, which indicated that metal cations may make the oxalate unavailable by chelating it. H2PO4 and HPO4 inhibited the activity of -2-G, but had no effect on ψG. Riboflavin, FMN and FAD inhibited ψG, but FMN and FAD had no effect on G (Table 2).
Journal Of Plant Physiology and Molecular Biology