Chevion M, Panos C, Paxton J
Biochim Biophys Acta. 1976 Mar 5;426(2):288-301. doi: 10.1016/0005-2736(76)90338-2.
Electron spin resonance spectroscopy (ESR) was used to compare the lipid organization, thermal stability and the physical state of the membrane of a human pathogen, Streptococcus pyogenes and its osmotically fragile L-form with this same L-form now adapted to grow under physiologically isotonic conditions (physiological L-form). Comparison of the hyperfine splittings of a derivative of 5-ketostearic acid spin label, I(12, 3), after incorporation into the membrane, revealed that the lipid chain rigidity of these membranes is in the order physiological L-form greater than osmotically fragile L-form greater than streptococcus. The signal intensity (of the center magnetic field line) versus temperature analysis showed two transitions for these membranes. The first with melting points of 45, 26 and 36 degrees C and second transition at 70, 63 and 60 degrees C for the physiological L-form, osmotically fragile L-form and streptococcal membranes, respectively. This same order of membrane lipid chain rigidity was seen from the cooperativities obtained for each of these systems from analysis based on the expression for an n-order reaction. The I(12, 3) and other probes with the paramagnetic group close to the methyl end of the molecule suggested that this difference in lipid chain rigidity between these organisms resides in the environment closer to the lipid head group region rather than in the hydrophobic lipid core. Another major finding was the binding of I(12, 3) at two or more different sites in each of the membranes examined. This change in lipid chain rigidity now provides an explanation to account for the survival of a previously osmotically fragile L-form in physiologically isotonic media by focusing on changes in the physical nature of its membrane. In so doing, it adds to and reinforces the speculation of the potential survival in vivo and involvement in pathogenesis of osmotically fragile aberrant forms of bacteria.
利用电子自旋共振光谱（ESR）比较了人类病原体化脓性链球菌及其渗透脆性L型菌的膜的脂质组织、热稳定性和物理状态，以及现在适应在生理等渗条件下生长的同一L型菌（生理L型）。将5-酮硬脂酸自旋标记物I(12, 3)的衍生物掺入膜后，对其超精细分裂进行比较，结果显示这些膜的脂质链刚性顺序为：生理L型＞渗透脆性L型＞链球菌。信号强度（中心磁场线）与温度的分析表明，这些膜有两个转变。生理L型、渗透脆性L型和链球菌膜的第一个转变熔点分别为45、26和36℃，第二个转变温度分别为70、63和60℃。从基于n阶反应表达式对每个系统进行分析得到的协同性来看，这些膜的脂质链刚性顺序也是如此。I(12, 3)和其他顺磁基团靠近分子甲基端的探针表明，这些生物体之间脂质链刚性的差异存在于更靠近脂质头部基团区域的环境中，而不是在疏水脂质核心中。另一个主要发现是，在每个检测的膜中，I(12, 3)在两个或更多不同位点结合。现在，脂质链刚性的这种变化通过关注其膜物理性质的变化，为解释先前渗透脆性L型菌在生理等渗培养基中的存活提供了一个理由。这样做增加并强化了关于渗透脆性异常细菌形式在体内潜在存活及参与发病机制的推测。
