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首页> 外文期刊>American Journal of Physiology >Electric field strength of membrane lipids from vertebrate species: membrane lipid composition and Na+-K+-ATPase molecular activity.
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Electric field strength of membrane lipids from vertebrate species: membrane lipid composition and Na+-K+-ATPase molecular activity.

机译：脊椎动物物种膜脂的电场强度：膜脂组成和Na + -K + -ATPase分子活性。

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摘要

Intramembrane electric field strength is a very likely determinant of the activity of ion-transporting membrane proteins in living cells. In the absence of any transmembrane electrical potential or surface potential, its magnitude is determined by the dipole potential of the membrane's lipid components and their associated water of hydration. Here we have used a fluorometric method to quantify the dipole potential of vesicles formed from lipids extracted from kidney and brain of 11 different animal species from four different vertebrate classes. The dipole potential was compared with the fatty acid composition and with the Na(+)-K(+)-ATPase molecular activity of each preparation. The magnitude of the dipole potential was found to be relatively constant across all animal species, i.e., 236-334 mV for vesicles prepared from the total membrane lipids and 223-256 mV for phospholipids alone. The significantly lower value for phospholipids alone is potentially related to the removal of cholesterol and/or other common soluble lipid molecules from the membrane. Surprisingly, no significant dependence of the dipole potential on fatty acid composition was found. This may, however, be due to concomitant compensatory variations in lipid head group composition. The molecular activity of the Na(+)-K(+)-ATPase was found to increase with increasing dipole potential. The fact that the dipole potential is maintained at a relatively constant value over a wide range of animal species suggests that it may play a fundamental role in ensuring correct ion pump conformation and function within the membrane.
机译：膜内电场强度是活细胞中离子转运膜蛋白活性的非常可能的决定因素。在没有任何跨膜电势或表面电势的情况下，其大小取决于膜脂质成分及其相关的水合水的偶极电势。在这里，我们已经使用荧光法来量化由从四种不同脊椎动物类别的11种不同动物物种的肾脏和大脑中提取的脂质形成的囊泡的偶极势。将偶极电势与每种制剂的脂肪酸组成和Na（+）-K（+）-ATPase分子活性进行比较。发现在所有动物物种中偶极电位的强度相对恒定，即，由总膜脂质制备的囊泡为236-334mV，而对于单独的磷脂为223-256mV。单独的磷脂的明显较低的值可能与胆固醇和/或其他常见的可溶性脂质分子从膜上的去除有关。令人惊讶地，没有发现偶极电势对脂肪酸组成的显着依赖性。但是，这可能是由于脂质头基组成的补偿性变化所致。发现Na（+）-K（+）-ATPase的分子活性随偶极电位的增加而增加。在多种动物物种中偶极电势都保持在相对恒定的值这一事实表明，它可能在确保正确的离子泵构型和膜内功能方面发挥重要作用。

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