摘要
分别从荞麦与大豆叶片中部分纯化了乙醇酸氧化酶 (GO ,EC1 .1 .3 .1 ) ,并研究其部分性质。结果显示荞麦与大豆叶片中GO的催化特性有明显差异 :大豆叶片中GO对乙醇酸Km值为 0 .3 1mmol/L ,对乙醛酸Km值为 1 .98mmol/L。外源草酸对GO氧化乙醇酸活性影响很小 ,但对其氧化乙醛酸活性抑制明显 ,5mmol/L草酸可抑制 44%。而荞麦叶片中GO性质有所不同 :GO对乙醇酸Km为 0 .46mmol/L ,对乙醛酸Km为 0 .85mmol/L。草酸对荞麦GO氧化乙醇酸活性影响也很小 ,对其氧化乙醛酸活性的抑制作用明显小于大豆 ,5mmol/L草酸只抑制 2 4%。上述研究结果表明 ,荞麦GO对乙醛酸的亲和力明显强于大豆 ,并且草酸对其GO氧化乙醛酸活性影响较小。因此相对于大豆而言 ,GO可能在荞麦叶片草酸合成中起重要作用。
In this study, glycolate oxidase (GO) was partially purified from both buckwheat and soybean leaves and then compared in terms of the catalytic property. It turned out that differences existed between the two kinds of GO. For soybean GO the Km for glycolate and glyoxylate was 0.31 mmol/L, 1.98 mmol/L, respectively. The oxidation of glycolate was only slightly inhibited but the oxidation of glyoxylate was inhibited by 44% in presence of 5 mmol/L oxalate. It can be inferred that once oxalate is accumulating to a certain level, its synthesis is suppressed by itself so that oxalate in soybean leaves can not accumulate to a certain high level. For buckwheat GO, the Km for glycolate and glyoxylate was 0.46 mmol/L, 0.85 mmol/L, respectively, indicating the affinity for glyoxylate is obviously higher than soybean GO. The oxidation of glycolate was also slightly inhibited and the oxidation of glyoxylate was inhibited only 24% in presence of 5 mmol/L oxalate. So comparatively, because of the GO differene, buckwheat leaves may have a higher rate of synthesizing oxalate and also be allowed to accumulate a higher level of oxalate.
出处
《广西植物》
CAS
CSCD
北大核心
2004年第2期184-187,共4页
Guihaia