研究富硒螺旋藻(SeSP)培养生物转化含硒蛋白质(SeP)中硒的含量及分布，观察SeP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(SePC)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SeP组份，化学发光方法检测SeP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，SeSP总蛋白中硒含量提高了32倍，可达805.48 μg/g，其中75.81%分布于25 ku以下小分子量含硒蛋白质(LMWSeP)中，LA-ICP-MS证明纯化SePC亚基含有稳定共价结合活性硒元素，LMWSeP对自由基的直接最大清除率在70%以上。结果提示，利用SeSP培养可转化生产活性SeP，SeSP中低分子量SeP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 (SeP) in Se-enriched Streptomyces platensis (SeSP) were explored. Additionally, the in vitro scavenging activity of oxygen free radicals by SeP 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 (SePC) within the electrophoresis gel. The in vitro clearance of superoxide and hydroxyl free radicals by SeP was investigated by chemiluminescence. The results showed that Se content in SeSP-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 SePs (LMWSeP), with molecular weights ≤ 25 ku. LA-ICP-MS results confirmed that purified SePC subunits contained stable, covalently-bound, active Se. The maximum clearance rate of free radicals by LMWSeP was over 70%. The findings suggest that SeSP cultures could be used to produce active SeP by biotransformation. The LMWSeP components in SeSPs 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.

广东省科技计划项目(2012B031800437、2013B010404029)；国家自然科学基金项目(20975045)资助