Thakur Kshema, Kaur Tarnjeet, Singh Jatinder, Rabbani Gulam, Khan Rizwan H, Hora Rachna, Kaur Manpreet
Department of Molecular Biology & Biochemistry, Guru Nanak Dev University, Amritsar, 143005, Punjab, India.
Department of Human Genetics, Guru Nanak Dev University, Amritsar, 143005, Punjab, India.
Int J Biol Macromol. 2017 Nov;104(Pt A):1267-1279. doi: 10.1016/j.ijbiomac.2017.06.123. Epub 2017 Jul 3.
Non-immune carbohydrate binding proteins are broadly defined as lectins. Having been reported from all kingdoms of life, phytolectins are the most widely studied group of lectins. Sauromatum guttatum agglutinin (SGA) was isolated from the plant tubers and characterized for structural variations due to solvent perturbation using polarimetry, fluorescence and light scattering. For the β-sheet rich SGA, a pH and temperature induced molten globule like intermediate was identified. In isothermal titration microcalorimetry, SGA demonstrated cooperative binding to a complex glycoprotein in enthalpically driven mechanism. Fine sugar specificity exploration identified core pentasaccharide as the most common and highest binding motif with complex N-glycans and fucosylated core N-glycans as additional motifs. Molecular cloning of SGA which has previously been demonstrated to have anti-cancer and anti-insect activities is being reported for the first time. Full length cDNA sequence was obtained with RACE-PCR based upon the conserved carbohydrate recognition site [QXDXNXVXY] present in all GNA-related lectins. Quaternary structure was proposed by homology modeling and an attempt was made to explain the structure-function relationship by in silico analysis.
非免疫性碳水化合物结合蛋白被广泛定义为凝集素。植物凝集素存在于所有生物界，是研究最为广泛的一类凝集素。从植物块茎中分离出了斑龙芋凝集素（SGA），并利用旋光法、荧光法和光散射法对其因溶剂扰动引起的结构变化进行了表征。对于富含β-折叠的SGA，鉴定出了一种pH和温度诱导的类熔球中间体。在等温滴定量热法中，SGA在焓驱动机制下表现出与一种复合糖蛋白的协同结合。精细的糖特异性探索确定核心五糖是与复合N-聚糖结合最常见且亲和力最高的基序，复合N-聚糖和岩藻糖基化核心N-聚糖则是其他基序。此前已证明具有抗癌和抗昆虫活性的SGA的分子克隆首次被报道。基于所有与雪花莲凝集素相关的凝集素中存在的保守碳水化合物识别位点[QXDXNXVXY]，通过RACE-PCR获得了全长cDNA序列。通过同源建模提出了四级结构，并尝试通过计算机分析解释结构-功能关系。
