Dehlinger P J, Jost P C, Griffith O H
Proc Natl Acad Sci U S A. 1974 Jun;71(6):2280-4. doi: 10.1073/pnas.71.6.2280.
The lipid binding properties of the membrane protein cytochrome b(5) (detergent-extracted from calf liver microsomal preparations) were characterized by studying the interaction of spin-labeled lipids (5-, 12-, and 16-doxylstearic acid and 5- and 16-doxylphosphatidyl-choline, where doxyl refers to the nitroxide moiety) with cytochrome b(5), using electron spin resonance spectroscopy. The intact cytochrome b(5) molecule immobilizes all of the lipid spin labels, while the segment of cytochrome b(5) released by trypsin does not affect lipid mobility. The immobilization of lipid spin labels on the hydrophobic surface of intact cytochrome b(5) is not appreciably altered by associating the protein with liposomes. Differences in polarity of the lipid binding sites between cytochrome b(5) and phospholipid vesicles were also observed. The lipid binding sites on cytochrome b(5) are hydrophobic by conventional criteria, but are more polar than the interior of fluid phospholipid bilayers.
通过电子自旋共振光谱法研究自旋标记脂质（5-、12-和16-二氧硬脂酸以及5-和16-二氧磷脂酰胆碱，其中二氧指氮氧自由基部分）与细胞色素b(5)的相互作用，对膜蛋白细胞色素b(5)（从小牛肝微粒体制剂中用去污剂提取）的脂质结合特性进行了表征。完整的细胞色素b(5)分子固定所有脂质自旋标记，而胰蛋白酶释放的细胞色素b(5)片段不影响脂质流动性。完整细胞色素b(5)疏水表面上脂质自旋标记的固定化不会因该蛋白与脂质体结合而发生明显改变。还观察到细胞色素b(5)与磷脂囊泡之间脂质结合位点极性的差异。按照传统标准，细胞色素b(5)上的脂质结合位点是疏水的，但比流体磷脂双层内部的极性更强。
