Lateral diffusion of lipids in membranes by pulse saturation recovery electron spin resonance.
Lateral diffusion of lipids in membranes by pulse saturation recovery electron spin resonance.
复制标题
通过脉冲饱和恢复电子自旋共振实现膜中脂质的横向扩散。
DOI：
10.1073/pnas.84.4.964
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发表时间：
1987
影响因子：
11.1
通讯作者：
J. S. Hyde
中科院分区：
文献类型：
--
作者：
J. Yin;M. Pasenkiewicz;J. S. Hyde
短脉冲饱和恢复电子自旋共振方法已用于测量多层脂质体分散体中硝基氧标记的脂质的横向扩散。使用具有单独和一起引入的14N和15N同位素的硝基氧化物。已经编写并求解了涉及多个叠加指数的复杂饱和恢复信号的微分方程。时间常数包含两种同位素的自旋晶格弛豫时间 (T1e)、海森堡交换率和核自旋晶格弛豫时间 (T1n) 的各种组合。通过幅度和时间常数的蒙特卡罗变化来拟合高质量信号。通过验证以下内容，对该方法的可靠性进行了广泛测试：(i) 预测的指数数与实验数一致；(ii) 确定的弛豫参数与观察到的超精细转变无关；(iii) 时间常数与饱和脉冲长度无关；(iv) 当通过改变浓度来改变海森堡交换时，T1e 和 T1n 不会改变；(v) 海森堡交换确实与浓度成正比。已经确定，使用此处描述的方法可以可靠地测量各种条件下的双分子碰撞率。该方法取决于微摩尔浓度下的双分子碰撞率与硝基氧自旋晶格弛豫概率的良好匹配。
Short-pulse saturation recovery electron spin resonance methods have been used to measure lateral diffusion of nitroxide-labeled lipids in multilamellar liposomal dispersions. Nitroxides with 14N and 15N isotopes introduced both separately and together were used. Differential equations have been written and solved for complex saturation recovery signals involving several superimposed exponentials. The time constants contain various combinations of the spin-lattice relaxation time (T1e) for both isotopes, Heisenberg exchange rates, and nuclear spin-lattice relaxation times (T1n). Signals of high quality were fitted by Monte Carlo variation of the amplitudes and time constants. The reliability of the approach was tested extensively by verifying that (i) the predicted number of exponentials agreed with the experimental number, (ii) relaxation parameters that were determined were independent of the observed hyperfine transition, (iii) the time constants were independent of saturating pulse length, (iv) T1e and T1n do not change when Heisenberg exchange is changed by varying the concentration, and (v) Heisenberg exchange is indeed proportional to the concentration. It has been established that bimolecular collision rates over a wide range of conditions can be reliably measured using the methodology described here. The methods depend on the favorable match of bimolecular collision rates at micromolar concentrations to nitroxide spin-lattice relaxation probabilities.