Rottem S, Markowitz O, Hasin M, Razin S
Eur J Biochem. 1979 Jun;97(1):141-6. doi: 10.1111/j.1432-1033.1979.tb13095.x.
The outer membranes of the smooth Proteus mirabilis S1959 strain and its rough R13, R110, R51 and R45 mutants were isolated by sonication of the cells and sucrose density gradient centrifugation. The outer membrane of the rough strains had a lower density than that of their parent smooth strain, but the protein-to-phospholipid ratios were the same. The electrophoretic patterns of outer membrane polypeptides of the S and R strains in sodium dodecylsulfate/polyacrylamide gels were identical, with two major polypeptide bands, C1 and C2 (Mr 39,000 and 38,000) predominating. The C1 polypeptide band was a heat-modifiable polypeptide, which migrated as a band at Mr 33,000 when membranes were solubilized at 37 degrees C or 50 degrees C, and at Mr 39,000 when solubilization was at 100 degrees C. Susceptibility of outer membrane polypeptides to proteolytic digestion was found to be higher in isolated outer membrane preparations of the rough strains than in the smooth strain, suggesting that the availability of the polypeptide chains to proteolytic activity depends on the length of the polysaccharide chains of the outer membrane lipopolysaccharide.
通过对奇异变形杆菌光滑型S1959菌株及其粗糙型R13、R110、R51和R45突变株进行细胞超声破碎和蔗糖密度梯度离心，分离出其外膜。粗糙型菌株的外膜密度低于其亲本光滑型菌株，但蛋白质与磷脂的比例相同。在十二烷基硫酸钠/聚丙烯酰胺凝胶中，S型和R型菌株外膜多肽的电泳图谱相同，有两条主要的多肽带，即C1和C2（分子量分别为39,000和38,000）占主导。C1多肽带是一种热可修饰多肽，当膜在37℃或50℃溶解时，它以分子量33,000的条带迁移，而在100℃溶解时以分子量39,000的条带迁移。发现粗糙型菌株的分离外膜制剂中，外膜多肽对蛋白水解消化的敏感性高于光滑型菌株，这表明多肽链对蛋白水解活性的可及性取决于外膜脂多糖多糖链的长度。
