螺旋藻富硒转化含硒蛋白质的鉴定及其抗氧化活性研究

Identification of Selenoproteins Formed via Biotransformation of Selenium-enriched Streptomyces platensis and Their Oxygen Free Radical Scavenging Activities

研究富硒螺旋藻(Se SP)培养生物转化含硒蛋白质(Se P)中硒的含量及分布,观察Se P在体外对氧自由基的清除效应。藻体总蛋白(TP)用SDS-PAGE电泳分离后,用电感偶合等离子体质谱技术(ICP-MS)对不同分子量范围蛋白质中的硒含量进行精确定量;通过激光烧蚀(LA)-ICP-MS对纯化含硒藻蓝蛋白(Se PC)硒含量在电泳胶上进行原位检测;用制备SDS-PAGE凝胶电泳分离纯化不同分子量的Se P组份,化学发光方法检测Se P在体外对超氧自由基和羟自由基的清除作用。结果发现,与未富硒培养的螺旋藻(SP)相比,Se SP总蛋白中硒含量提高了32倍,可达805.48μg/g,其中75.81%分布于25 ku以下小分子量含硒蛋白质(LMWSe P)中,LA-ICP-MS证明纯化Se PC亚基含有稳定共价结合活性硒元素,LMWSe P对自由基的直接最大清除率在70%以上。结果提示,利用Se SP培养可转化生产活性Se P,Se SP中低分子量Se P组份是一种具有较高抗氧化活性的天然活性硒资源,其中硒的存在形态、合成转化机制和体内生物活性有待深入研究。

Selenium(Se) content and distribution of Se-containing biotransformation proteins(Se P) in Se-enriched Streptomyces platensis(Se SP) were explored. Additionally, the in vitro scavenging activity of oxygen free radicals by Se P was studied. Total proteins(TP) in S. platensis were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE) and Se content in different molecular-weight proteins was measured using inductively-coupled plasma mass spectrometry(ICP-MS). Laser ablation(LA)-ICP-MS was used for in situ detection of Se content in purified Se phycocyanin(Se PC) within the electrophoresis gel. The in vitro clearance of superoxide and hydroxyl free radicals by Se P was investigated by chemiluminescence. The results showed that Se content in Se SP-TP was 32-fold higher than that in non-enriched S. platensis(SP), reaching 805.48 μg/g, while 75.81% oftotal Se was distributed in low-molecular weight Se Ps(LMWSe P), with molecular weights ≤ 25 ku. LA-ICP-MS results confirmed that purified Se PC subunits contained stable, covalently-bound, active Se. The maximum clearance rate of free radicals by LMWSe P was over 70%. The findings suggest that Se SP cultures could be used to produce active Se P by biotransformation. The LMWSe P components in Se SPs are a source of natural Se with high anti-oxidation activity. Further studies are required to determine the form of Se, transformation mechanism, and in vivo bioactivity.