Souzu H
Biochim Biophys Acta. 1980 Dec 2;603(1):13-26. doi: 10.1016/0005-2736(80)90387-9.
Freeze-thawing of Escherichia coli cells caused a release of cell membrane components such as protein, phospholipids and lipopolysaccharides. A greater amount of release and a lesser extent of cell survival were seen in slow freeze-thawing than in rapid freeze-thawing. Several dehydrogenases in the cells were also freed. The mode of release was also dependent on the rate of freeze-thawing. The materials released by slow freeze-thawing were found to be mostly composed of outer membrane components, whereas the materials released by rapid freeze-thawing contained cytoplasmic as well as outer membrane components. The chemical composition of these fragments differed significantly from that of the original membranes. The relative content of cytoplasmic membrane-bound enzymes in these fragments also differed from that of the cytoplasmic membrane. The fragmentation was assumed to have resulted mainly from the crystallization of external water. In slow fraeeze-thawing, it was considered that the phase separation of the membrane phospholipid bilayer increased the possibility of outer membrane fragmentation. Rapid freeze-thawing caused cytoplasmic membrane damage to the cells as well as to the outer membrane. In rapid freeze-thawing, the effect of phase separation appeared to be small because of rapid passage through the transition temperatures. The presence of 10% glycerol completely inhibited the release of cellular materials and enzymes. Cell survival was maintained at a high level in the glycerol-treated samples whether freeze-thawed slowly or rapidly.
大肠杆菌细胞的冻融导致细胞膜成分如蛋白质、磷脂和脂多糖的释放。与快速冻融相比，缓慢冻融时释放量更大，细胞存活率更低。细胞中的几种脱氢酶也被释放出来。释放模式也取决于冻融速率。发现缓慢冻融释放的物质主要由外膜成分组成，而快速冻融释放的物质包含细胞质以及外膜成分。这些片段的化学成分与原始膜有显著差异。这些片段中细胞质膜结合酶的相对含量也与细胞质膜不同。这种碎片化被认为主要是由于外部水的结晶。在缓慢冻融中，认为膜磷脂双层的相分离增加了外膜碎片化的可能性。快速冻融对细胞的细胞质膜以及外膜都造成了损伤。在快速冻融中，由于快速通过转变温度，相分离的影响似乎较小。10%甘油的存在完全抑制了细胞物质和酶的释放。无论缓慢还是快速冻融，甘油处理的样品中细胞存活率都维持在较高水平。
