Witholt B, Heerikhuizen H V, De Leij L
Biochim Biophys Acta. 1976 Sep 7;443(3):534-44. doi: 10.1016/0005-2736(76)90471-5.
Lysozyme fails to penetrate through the outer membrane of stationary phase cells of Escherichia coli when it is simply added to suspensions of plasmolyzed cells. Lysozyme penetrates the outer membrane only when these cells are exposed to a mild osmotic shock in the presence of EDTA and lysozyme. In the presence of Mg2+, the outer membrane is stabilized sufficiently so that there is no lysozyme penetration during osmotic shock. If Mg2+ is added after an osmotic shock has been used to cause lysozyme to penetrate a destabilized outer membrane, the outer membrane is stabilized once again. In this case however, cells are converted to spheroplasts by the lysozyme which has gained access to the murein layer prior to the addition of Mg2+. Mg2+ stabilizes the outer membranes of these spheroplasts sufficiently so that they remain immune to lysis even in the absence of osmotic stabilizers such as sucrose. These results are discussed in terms of current information on the structure of the murein layer and the outer membrane.
当溶菌酶简单地添加到质壁分离细胞的悬浮液中时，它无法穿透大肠杆菌稳定期细胞的外膜。只有当这些细胞在乙二胺四乙酸（EDTA）和溶菌酶存在的情况下受到轻度渗透休克时，溶菌酶才能穿透外膜。在镁离子（Mg2+）存在的情况下，外膜被充分稳定，以至于在渗透休克期间没有溶菌酶穿透。如果在使用渗透休克使溶菌酶穿透不稳定的外膜后添加Mg2+，外膜会再次稳定。然而，在这种情况下，细胞会被溶菌酶转化为原生质球，溶菌酶在添加Mg2+之前已经进入了胞壁质层。Mg2+充分稳定这些原生质球的外膜，以至于即使在没有蔗糖等渗透稳定剂的情况下，它们仍然对裂解免疫。根据目前关于胞壁质层和外膜结构的信息对这些结果进行了讨论。
