Gordon L M, Looney F D, Curtain C C
Anesthesia Service, J.L. Pettis Veterans Administration Hospital, Loma Linda, California 92357.
J Membr Biol. 1989 Oct;111(2):155-68. doi: 10.1007/BF01871779.
A model for the binding of 5-nitroxide stearate, I(12.3), to human erythrocyte ghosts was developed by comparing spin probe interactions with ghosts and liposomes prepared from ghosts. At low probe/lipid (P/L less than 1/2500), I(12.3) binds to a similar class of high-affinity, noninteracting sites in both ghosts and liposomes, indicating that lipid moieties are responsible for probe uptake. Saturation occurs in both systems with increasing P/L, and, at higher loading (e.g., P/L = 1/360 for ghosts and liposomes), the probe inserts itself at initially dilute sites to form a class of low-affinity sites consisting of clusters of variable size. At still higher P/L ranges (greater than 1/100), much increased probe uptake was observed in ghosts than in liposomes, which was attributed to another class of low-affinity sites, representing nonspecific interactions of I(12.3) with membrane proteins. The nature of the spectral components and ultrafiltration experiments with ghosts labeled at high P/L indicate that both 'dilute' and 'clustered' I(12.3) are due to membrane-incorporated probe.
通过比较自旋探针与红细胞膜空壳以及由红细胞膜空壳制备的脂质体之间的相互作用，建立了5 - 硬脂酸硝基氧（I(12.3)）与人红细胞膜空壳结合的模型。在低探针/脂质比（P/L小于1/2500）时，I(12.3)在红细胞膜空壳和脂质体中均与一类相似的高亲和力、非相互作用位点结合，这表明脂质部分负责探针的摄取。随着P/L增加，两个系统均出现饱和现象，并且在较高负载量时（例如，红细胞膜空壳和脂质体的P/L = 1/360），探针插入最初稀释的位点，形成一类由大小可变的簇组成的低亲和力位点。在更高的P/L范围（大于1/100）时，观察到红细胞膜空壳中的探针摄取量比脂质体中增加得多，这归因于另一类低亲和力位点，代表I(12.3)与膜蛋白的非特异性相互作用。光谱成分的性质以及对高P/L标记的红细胞膜空壳进行的超滤实验表明，“稀释”和“聚集”的I(12.3)均归因于掺入膜中的探针。
