Mobarak Qamsari Elahe, Kasra Kermanshahi Rouha, Erfan Mohammad, Ghadam Parinaz, Sardari Soroush, Eslami Neda
Department of Microbiology, Faculty of Biological sciences, Alzahra University, Tehran, Iran.
Department of Pharmaceutics, School of Pharmacy, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Int J Biol Macromol. 2017 Feb;95:1004-1010. doi: 10.1016/j.ijbiomac.2016.10.089. Epub 2016 Oct 27.
In this work, some important characteristics of surface layer (S-layer) proteins extracted from two new and native Lactobacillus strains, L.brevis KM3 and L.brevis KM7, were investigated. The presence of S-layer on the external surface of L.brevis KM3 was displayed by thin sectioning and negative staining. SDS-PAGE analysis were shown same dominant protein bands approximately around 48kDa for both S-layer proteins. Moreover, the S-layer reappeared when LiCl treated cells were allowed to grow again. Protein secondary structure and thermal behavior were evaluated by using circular dichroism (CD) and differential scanning calorimetry (DSC), respectively. Both S-layer proteins had high content of β-sheet and low amount of α-helix. The thermograms of lyophilized S-layer proteins of L.brevis KM3 and L.brevis KM7 showed one transition peak at 67.9°C and 59.14°C, respectively. To determine monodispersity of extracted S-layer proteins, dynamic light scattering (DLS) was used. The results indicated that the main population of S-layer molecules in two tested lactobacillus strains were composed of monomer with an expected diameter close to 10nm. Furthermore, Zeta potential measurements were showed positive potential for both S-layer proteins, as expected. Our results could be used as the basis for biotechnological applications of these two new S-layer proteins.
在这项工作中，对从两株新的本地短乳杆菌菌株（短乳杆菌KM3和短乳杆菌KM7）中提取的表层（S层）蛋白的一些重要特性进行了研究。通过超薄切片和负染色显示了短乳杆菌KM3外表面存在S层。SDS-PAGE分析表明，两种S层蛋白的主要蛋白条带大约在48kDa左右相同。此外，当用LiCl处理的细胞再次生长时，S层重新出现。分别使用圆二色性（CD）和差示扫描量热法（DSC）评估蛋白质二级结构和热行为。两种S层蛋白都具有高含量的β-折叠和低含量的α-螺旋。短乳杆菌KM3和短乳杆菌KM7冻干S层蛋白的热谱图分别在67.9°C和59.14°C显示一个转变峰。为了确定提取的S层蛋白的单分散性，使用了动态光散射（DLS）。结果表明，两种测试的乳杆菌菌株中S层分子的主要群体由预期直径接近10nm的单体组成。此外，如预期的那样，两种S层蛋白的Zeta电位测量均显示为正电位。我们的结果可作为这两种新的S层蛋白生物技术应用的基础。
