转小麦铁蛋白基因酵母的抗氧化活性

铁蛋白是广泛存在于动、植物和微生物中的储铁关键蛋白，具有调节铁代谢平衡、消除亚铁离子引起的氧化毒性等作用。本研究克隆了小麦铁蛋白基因，构建其真核表达载体，经筛选、检测得到具有形成活性小麦铁蛋白多聚体能力的转基因酵母。转基因酵母与转空载体的对照酵母相比不仅可有效清除过氧化氢(H₂O₂)，而且还具清除羟自由基(^.OH)和超氧阴离子(O₂^?)的能力；×OH、O₂^?和H₂O₂对转基因酵母的半致死浓度(LD₅₀)分别为0.40、1.00和36.91 mmol L^-1，比对照酵母分别提高了37.93%、47.06%和77.03%。不同浓度转基因酵母对×OH、O₂^?和H₂O₂清除能力的回归方程分别为一元三次多项式、对数方程和负指数方程。说明小麦铁蛋白基因的真核表达产物可以有效清除3种活性氧，而且具有较为复杂的互不相同的作用机制。

Antioxidative Activities of Transgenic Yeast with Ferritin Gene from Wheat

Ferritin, a key protein to store iron, is widely distributed in animal, plant, and microbe. Ferritin can regulate the balance in iron metabolism and decrease the oxidative damage caused by ferrous ion. It is generally recognized that the antioxidant activity of ferritin is mainly caused by integrating ferrous ion among cells, and thereby decreasing the generation of Fenton reaction. In addition to the antioxidant pathway against hydrogen peroxide (H₂O₂), less information is available on other antioxidative pathways and mechanism of ferritin. In this study, a ferritin gene was cloned from wheat (Triticum aestivum L.), and its expression vehicle of eukaryotic cell was constructed and transformed into yeast (Saccharomyces cerevisiae). Compared with the control yeasts, the transgenic yeasts were able to scavenge H₂O₂,O₂^?and ·OH effectively. The half lethal density (LD₅₀) of transgenic yeasts induced by the three types of active oxygen (·OH, O₂^?and H₂O₂) was 0.40, 1.00, and 36.91 mmol L^-1, which increasedby37.93%, 47.06%, and 77.03% compared with the control respectively. The abilities for eliminating ·OH, O₂^?, and H₂O₂ of the trsnsgenic yeast per unit concentiation were quantitated with cubic polynomial, logarithmic, and negative exponential equations based on yeast concentration respectively. These results demonstrated that expressed products of wheat ferritin gene in eukaryotic orgamism can effectivly in eliminate various types of active oxygen with different and complex mechanisms.