小麦萌发素G和ψG的纯化及其部分特性

利用亲和层析方法纯化了小麦草酸氧化酶G和ψG,并对其生化特性进行了初步分析.G和ψG的最适pH为3.5,在60℃以下较稳定.当草酸浓度大于0.2mmol/L时,G和ψG的活性受到抑制.G和ψG的Km值分别为0.084和0.053mmol/L.0.1 mmol/L的EDTA、NH4 、Cl-、Mn2 、Mg2 、Na 和K 对G和ψG的活性没有影响,0.1 mmol/L的Zn2 、Cu2 、Fez 、Al3 、CO32-、NO3-和SO42-抑制G和ψG的活性.0.1 mmol/L的H2PO4-和HPO42-仅抑制G的活性.0.1 mmol/L的核黄素、FMN和FAD抑制ψG活性,G的活性则不受FAD和FMN的影响.

Purification and Some Characteristics of Germins G and ψG from Wheat

By affinity chromatography, germins G and psiG were purified from roots of wheat seedling and wheat embryos imbibition for 4 h. Characterization of the germins G and psiG were studied. The results showed that G and psiG were stable at temperatures lower than 60 degrees C, and had an optimum pH at 3.5. The Km value of G for oxalate was 0.084 mmol/L, while that of psiG was 0.053 mmol/L. Oxalate showed substrate inhibition effect above 0.2 mmol/L on G and psiG. EDTA, NH(+)(4), Mn(2+), Mg(2+), Na(+) and K(+) at a concentration of 0.1 mmol/L had no effect on OxO activity. CO(2-)(3), NO(-)(3) and SO(2-)(4) at a concentration of 0.1 mmol/L inhibited partially the activities of G and psiG, 0.1 mmol/L Cu(2+), Fe(2+), Al(3+) completely inhibited the activities of G and psiG, 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. H(2)PO(-)(4) and HPO(2-)(4) inhibited the activity of G, but had no effect on psiG. Riboflavin, FMN and FAD inhibited psiG, but FMN and FAD had no effect on G.