University of Hyderabad, India.
Biosci Rep. 2010 Apr 21;30(5):341-9. doi: 10.1042/BSR20090117.
The chito-oligosaccharide-specific lectin from pumpkin (Cucurbita maxima) phloem exudate has been purified to homogeneity by affinity chromatography on chitin. After SDS/PAGE in the presence of 2-mercaptoethanol, the pumpkin phloem lectin yielded a single band corresponding to a molecular mass of 23.7 kDa, whereas ESI-MS (electrospray ionization MS) gave the molecular masses of the subunit as 24645 Da. Analysis of the CD spectrum of the protein indicated that the secondary structure of the lectin consists of 9.7% alpha-helix, 35.8% beta-sheet, 22.5% beta-turn and 32.3% unordered structure. Saccharide binding did not significantly affect the secondary and tertiary structures of the protein. The haemagglutinating activity of pumpkin phloem lectin was mostly unaffected in the temperature range 4-70 degrees C, but a sharp decrease was seen between 75 and 85 degrees C. Differential scanning calorimetric and CD spectroscopic studies suggest that the lectin undergoes a co-operative thermal unfolding process centred at approx. 81.5 degrees C, indicating that it is a relatively stable protein.
南瓜（Cucurbita maxima）韧皮部渗出物中的壳寡糖特异性凝集素已通过亲和层析在壳聚糖上纯化为均相。在存在 2-巯基乙醇的情况下进行 SDS/PAGE 后，南瓜韧皮部凝集素产生与 23.7 kDa 分子量相对应的单一条带，而 ESI-MS（电喷雾电离 MS）给出了亚基的分子量为 24645 Da。对蛋白质的 CD 光谱分析表明，该凝集素的二级结构由 9.7%的α-螺旋、35.8%的β-折叠、22.5%的β-转角和 32.3%的无规卷曲组成。糖结合不会显著影响蛋白质的二级和三级结构。南瓜韧皮部凝集素的血凝活性在 4-70°C 的温度范围内基本不受影响，但在 75-85°C 之间急剧下降。差示扫描量热法和 CD 光谱研究表明，该凝集素经历一个约 81.5°C 的协同热展开过程，表明它是一种相对稳定的蛋白质。
