Yang J, Anderle G L, Mendelsohn R
Department of Chemistry, Rutgers University, Newark College of Arts and Sciences, NJ 071012.
Biochim Biophys Acta. 1990 Jan 15;1021(1):27-32. doi: 10.1016/0005-2736(90)90379-3.
Ca2(+)-ATPase from rabbit skeletal muscle has been isolated, purified, and reconstituted into vesicles containing binary mixtures of 1-palmitoyl-2-oleoylphosphatidylethanolamine (POPE)/cholesterol. Fourier transform infrared spectroscopy (FTIR) was used to investigate the effect of protein on the thermotropic behavior of POPE in these reconstituted ternary complexes. The CH2 symmetric stretching modes of the phospholipid acyl chains near 2850 cm-1 served as an index of the melting process. The thermotropic transition of the POPE component in a 103:12:1 (POPE/cholesterol/Ca2(+)-ATPase) complex was shifted to lower temperatures compared with a protein-free binary lipid mixture of the same relative proportions. When combined with differential scanning calorimetric (DSC) data for the binary (POPE/cholesterol) lipid systems, this observation suggests that Ca2(+)-ATPase preferentially sequesters 15-35 molecules of POPE from the lipid mixture and therefore excludes cholesterol from its immediate environment. Higher levels of cholesterol in ternary complexes progressively eliminate the cooperative POPE melting event.
已从兔骨骼肌中分离、纯化出Ca2(+)-ATP酶，并将其重构成含有1-棕榈酰-2-油酰磷脂酰乙醇胺（POPE）/胆固醇二元混合物的囊泡。利用傅里叶变换红外光谱（FTIR）研究了蛋白质对这些重构三元复合物中POPE热致行为的影响。磷脂酰基链在2850 cm-1附近的CH2对称伸缩模式用作熔化过程的指标。与相同相对比例的无蛋白质二元脂质混合物相比，103:12:1（POPE/胆固醇/Ca2(+)-ATP酶）复合物中POPE组分的热致转变向更低温度偏移。结合二元（POPE/胆固醇）脂质体系的差示扫描量热法（DSC）数据，该观察结果表明Ca2(+)-ATP酶优先从脂质混合物中隔离15 - 35个POPE分子，因此将胆固醇排除在其紧邻环境之外。三元复合物中较高水平的胆固醇逐渐消除协同的POPE熔化事件。
