家蝇蛹甘露糖结合凝集素的结构及免疫调节作用

Structure and immunomodulation activity of a novel mannose binding lectin from housefly pupae

摘要:

分析了一种分子量为24 kDa，具有免疫活性的新型家蝇蛹甘露糖结合凝集素 (MBL-1) 的结构，为深入研究其结构与功能之间的关系提供依据。首先通过凝胶电泳及Schiff’s染色确定此新型家蝇蛹凝集素具有糖链结构。通过β-消除反应、红外光谱、原子力显微镜和蛋白N端测序仪对其结构进行分析。结果表明MBL-1是一种存在N-糖苷键，蛋白含量为97.20％、糖含量为2.55％，直径60~100 nm的椭球状蛋白单体，肽链N-端封闭。MTT实验证明MBL-1可以明显促进巨噬细胞的增殖且具有浓度依赖性，扫描电镜观察结果表明，MBL-1作用后的巨噬细胞形态呈现活化状态。可见，分离纯化出的MBL-1是一种具有明显的免疫调节活性的新型凝集素，为开发天然免疫增强剂和进一步分析其结构及其作用机制提供了参考。

Abstract:

We purified a novel mannose binding lectin form Musca domestica pupae by affinity chromatography on Con A-Sepharose 4B and DEAE weak anion-exchange chromatography. By SDS-PAGE, MBL-1 yielded a single band with the molecular weight of 24 kDa. It was a glycoprotein detected by periodic acid-schiff’s staining reaction, with 97.36% protein and 2.1% oligosaccharide. Meanwhile, the results of β-elimination reaction, infrared spectroscopy, atomic force microscopy and protein sequencing instrument show that MBL-1 was an ellipsoidal-shaped monomer with 60?100 nm in diameter. N-glycoside bond linked oligosaccharide chain and the N-terminal blocked peptide chain. Further study suggested that MBL-1 promote the proliferation of macrophage in a concentration-dependent manner. The scanning electron microscope analysis shows that MBL-1 promoted the activation of macrophages. These results show that MBL-1 purified from Musca domestica pupae possesses immune regulation effect, serving a reference basis to develop natural immune-modulator.