对自主拥有的多株乳酸菌进行了表层蛋白的分离和鉴定,并对其结构和性质进行了研究。采用LiCl溶液进行提取,经SDS-PAGE检测,确定嗜酸乳杆菌fb116、嗜酸乳杆菌fb115和瑞士乳杆菌fb213携带表层蛋白。采用差示扫描量热仪(DSC)测定,其变性温度分别为63.67℃,61.98℃和59.78℃。它们的氨基酸组成大致相同,疏水氨基酸含量高达45%,酸性氨基酸含量在21%左右,远高于碱性氨基酸。圆二色谱法(CD)分析显示,其二级结构相似,α-螺旋和β-折叠约占34%和12%。去除表层蛋白之后,3株菌株的自动聚集能力和表面疏水性出现下降,这提示表层蛋白的存在有助于乳酸菌黏附性能的发挥。

In the present study several lactobacillus carrying surface layer proteins had been screened from those owned by our laboratory.They were Lactobacillus acidophilus fb116,Lactobacillus acidophilus fb115 and Lactobacillus helveticus fb213.The thermal analysis of the lyophilized surface layer proteins were performed by differential scanning calorimetry(DSC).DSC analysis showed one phase transition with maxima located at ca.63.67℃,61.98 ℃ and 59.78 ℃ for these three proteins.The amino acid compositions of the three proteins were determined mostly the same,which had a high content(45%) of hydrophobic amino acids and a higher content(24%) of acidic amino acids then basic ones.By circular dichrosim(CD) spectra the secondary structures of the proteins were predicted to be composed similarly of 34% alpha-helix and 12% beta-sheet.After removal of surface layer proteins,the autoaggregation percentage and the cell surface hydrophobicity of the three lactobacillus were reduced.It was implied that the surface layer proteins played a role in adhesion property of Lactobacillus.