| 摘要: |
| 藻胆蛋白是某些藻类特有的捕光色素蛋白,其中天然别藻蓝蛋 白、藻蓝蛋白的抗氧化活性已经被证明。实验以2,2-盐酸脒基丙烷(AAPH)为自由基生成者,应用藏红花素退色反应为检测清除氢过氧自由基的方法,探讨 了在大肠杆菌(Escherichia coli)中表达并纯化的带有6×His(6×组氨酸)标签和带有麦芽糖结合蛋白(MBP)标签的重组别藻蓝蛋白及其α、β亚基的抗氧化活性。结果表明, 带有His标签的6×His-αAPC、6×His-βAPC和6×His-APC均显示出一定的清除氢过氧自由基的能力,其中6×His-βAPC清除氢过氧自由基的IC50值可达到27.2 mg/L,Ka/Kc(氢过氧自由基与重组别藻蓝蛋白和藏红花素反应的速度常数比)达到1.24,大于带有色素基团的天然APC清除氢过氧自由基能力 (IC50 57.5 mg/L);而带有MBP标签的重组别藻蓝蛋白亚基MBP-αAPC和MBP-βAPC和MBP-APC(rAPC)则无明显的清除能力。结果首次证实了 脱辅基蛋白具有清除氢过氧自由基能力,因而在天然藻胆蛋白中脱辅基蛋白是清除自由基的贡献者之一,这为进一步研究重组别藻蓝蛋白的抗肿瘤机理提供了线索。 |
| 关键词: 重组别藻蓝蛋白 清除自由基 2,2-盐酸脒基丙烷(AAPH) 藏红花素 |
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| 基金项目:国家863计划资助项目(2006AA090303);中国科学院知识创新项目(KZCX2-YW-209) |
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| Antioxidant activity comparison of different recombinant allophycocyanins |
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| Abstract: |
| The apo-allophycocyanin and its subunits expressed in Escherichia coli in our lab were purified with amylose affinity column or Ni+-chelating affinity column. Their peroxyl radical(generated by AAPH) scavenging properties were evaluated by competition kinetics of crocin bleaching. The results showed that only recombinant allophycocyanin fused with 6 His-tag and its α or β subunit can scavenge peroxyl radical successfully, and the separated β subunit had a higher inhibition effect on peroxyl radical than others, with an IC50 value of 27.2mg/L and the rate constant ratio of 1.24, higher than the native allophycocyanin with an IC50 value of 57.5mg/L .We also observed that recombinant allophycocyanin fused with MBP-tag and its α or β subunit had no remarkable scavenging ability on peroxyl radical. These results clearly suggested that apo-allophycocyanin is involved in the antioxidant and radical scavenging activity of allophycocyanin. The antioxidant activity may be partially responsible for the anti-tumor effect of the recombinant allophycocyanin. |
| Key words: recombinant allophycocyanin peroxyl radical scavenging AAPH crocin |
