Linden C D, Blasie J K, Fox C F
Biochemistry. 1977 Apr 19;16(8):1621-5. doi: 10.1021/bi00627a015.
The lipid fatty acid composition of the cytoplasmic membranes of Escherichia coli can be varied by growing an unsaturated fatty acid auxotroph in the presence of different fatty acid supplements. Electron spin resonance (ESR) studies of spin-label partitioning into the cytoplasmic membranes of different lipid fatty acid compositions as a function of temperature have been interpreted as indicating a broad order-to-disorder transition in the membrane lipids, the end points of the transition depending upon the fatty acid composition. We have utilized x-ray diffraction to confirm the ESR studies for three different fatty acid supplements (oleic, elaidic, and bromostearic). We found that the characteristic end-point temperatures detected by ESR were indeed the end-point temperatures of a broad order-to-disorder transition of the cytoplasmic membrane lipids. In addition, Patterson functions calculated from lamellar x-ray diffraction from partially oriented cytoplasmic membranes indicate a decrease in average membrane thickness upon fatty acid chain melting.
通过在不同脂肪酸补充剂存在的情况下培养不饱和脂肪酸营养缺陷型大肠杆菌，可以改变其细胞质膜的脂质脂肪酸组成。作为温度函数的、自旋标记物在不同脂质脂肪酸组成的细胞质膜中的分配情况的电子自旋共振（ESR）研究，已被解释为表明膜脂中存在广泛的有序到无序转变，该转变的终点取决于脂肪酸组成。我们利用X射线衍射来证实针对三种不同脂肪酸补充剂（油酸、反油酸和溴硬脂酸）的ESR研究。我们发现，ESR检测到的特征终点温度确实是细胞质膜脂质广泛有序到无序转变的终点温度。此外，从部分取向的细胞质膜的层状X射线衍射计算得到的帕特森函数表明，脂肪酸链熔化时平均膜厚度减小。
