栝楼籽中一种新的具有蛋白质生物合成抑制活性的多肽——Trichokirin-S1的分离、纯化和性质

改进了常规的核糖体失活蛋白的分离纯化方案 ,首先采用抽提蛋白体的方法 ,提高了分离效果 ,然后再经硫酸铵分级沉淀、FPLCMonoS阳离子交换层析和Superose12凝胶过滤层析等步骤 ,从栝楼种子中分离到一种新的多肽———trichokirin S1。经MALDI TOFMS质谱分析测得其分子量为 114 2 6。该肽的N端氨基酸序列为PRRKEG GSFDECCSE ,与一种存在于南瓜籽中的小分子核糖体失活蛋白 β moschin具有很高的同源性。trichokirin S1对核糖体失活的机制与天花粉蛋白 (TCS)一致 ,是rRNAN 糖苷酶催化型的 ,对兔网织红细胞裂解液系统蛋白质生物合成有较强的抑制作用 ,IC50 为 0 .71nmol L ,因而有可能开发成免疫毒素的高效“弹头”。

Purification and Characterization of Trichokirin-S1, a Novel Ribosome-inactivating Peptide from Seeds of Trichosanthes kirilowii

A novel peptide from the seeds of Trichosanthes kirilowii , trichokirin-S1, was purified by extraction of protein body, ammonia sulfate precipitation, Blue-gel affinity chromatography, FPLC Mono S ion exchange chromatography and Superose12 gel filtration chromatography. Its molecular weight was determined to be 11 426 by MALDI-TOF MS analysis. Its reaction mechanism to inactive ribosome was the same as that of the ribosome-inactivating protein trichosanthin, a rRNA N-glycosidase. The purified trichokirin-S1 showed a strong inhibitory activity on protein synthesis in cell-free rabbit reticulocyte lysate system, with IC 50 of 0.7 nmol/L. Therefore, trichokirin-S1 may be a promising and efficient toxin moiety of immunotoxins.