Interaction of horse heart and Thermus thermophilus type c cytochromes with phospholipid vesicles and hydrophobic surfaces
Interaction of horse heart and Thermus thermophilus type c cytochromes with phospholipid vesicles and hydrophobic surfaces
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DOI：
10.1529/biophysj.103.025114
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发表时间：
2004-06-01
影响因子：
3.4
通讯作者：
Lecomte, S
中科院分区：
文献类型：
--
作者：
Bernad, S;Oellerich, S;Lecomte, S
采用傅里叶变换红外光谱（FTIR）和浊度法研究了马心细胞色素c（cyt-c）和嗜热栖热菌细胞色素C-552（CYt-C-552）与二油酰磷脂酰甘油（DOPG）囊泡的结合。FTIR光谱显示，这两种细胞色素的三级结构变得更加开放时，绑定到DOPG囊泡，但这是更明显的cyt-c。它们的二级结构没有变化。湍流测量表明，它们的行为绑定到带负电荷的DOPG囊泡的重要差异。两种细胞色素都能使脂质体聚集和絮凝，但它们的方式不同。对于cyt-c，由于电荷中和，在聚集之前超过单层被吸附到脂质体表面上，而cyt-c（552）在远低于电荷中和所需的蛋白质/脂质比下引起聚集。因此，尽管cyt-c可能通过静电相互作用导致脂质体聚集，但cyt-c（552）不会以这种方式起作用。红外衰减全反射光谱（FTIR-ATR）显示，当与十八烷基三氯硅烷的疏水表面结合时，cyt-c失去了大部分二级结构，而cyt-c（552）将其结构域折叠成β结构。这种疏水效应可能是两种细胞色素与DOPG囊泡结合时行为差异的关键。
The binding of horse heart cytochrome c (cyt-c) and Thermus thermophilus cytochrome C-552 (CYt-C-552) to dioleoyl phosphatidylglycerol (DOPG) vesicles was investigated using Fourier transform infrared (FTIR) spectroscopy and turbidity measurements. FTIR spectra revealed that the tertiary structures of both cytochromes became more open when bound to DOPG vesicles, but this was more pronounced for cyt-c. Their secondary structures were unchanged. Turbidity measurements showed important differences in their behavior bound to the negatively charged DOPG vesicles. Both cytochromes caused the liposomes to aggregate and flocculate, but the ways they did so differed. For cyt-c, more than a monolayer was adsorbed onto the liposome surface prior to aggregation due to charge neutralization, whereas cyt c(552) caused aggregation at a protein/lipid ratio well below that required for charge neutralization. Therefore, although cyt-c may cause liposomes to aggregate by electrostatic interaction, cyt-c(552) does not act in this way. FTIR-attenuated total reflection spectroscopy (FTIR-ATR) revealed that cyt-c lost much of its secondary structure when bound to the hydrophobic surface of octadecyltrichlorosilane, whereas cyt-c(552) folds its domains into a beta-structure. This hydrophobic effect may be the key to the difference between the behaviors of the two cytochromes when bound to DOPG vesicles.