PHASE SEPARATION OF ACIDIC AND NEUTRAL PHOSPHOLIPIDS INDUCED BY HUMAN MYELIN BASIC-PROTEIN
PHASE SEPARATION OF ACIDIC AND NEUTRAL PHOSPHOLIPIDS INDUCED BY HUMAN MYELIN BASIC-PROTEIN
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DOI：
10.1021/bi00644a003
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发表时间：
1977-01-01
期刊：
影响因子：
2.9
通讯作者：
PAPAHADJOPOULOS, D
中科院分区：
文献类型：
--
作者：
BOGGS, JM;MOSCARELLO, MA;PAPAHADJOPOULOS, D
用差示扫描量热法检测了人中枢神经系统髓鞘碱性蛋白在酸性磷脂和中性磷脂混合物中诱导的脂相分离。使用磷脂酸、磷脂酰甘油和磷脂酰丝氨酸与磷脂酰胆碱(PC)的混合物，并在没有蛋白质的情况下几乎随机混合。将碱性蛋白质加入这些混合物中，导致相变温度向PC组分的温度移动，表明它结合并分离出酸性脂质，离开PC富集相。在某些情况下，还观察到了由于酸性脂质-碱性蛋白复合体而产生的转变。无论PC是混合物的较低熔点组分还是较高熔点组分，都会发生向PC组分转变温度的移动。这种蛋白质不仅与最先融化的脂类结合，而且即使在比中性脂类高得多的温度下融化，也会与酸性脂类结合。如果有足够的酸性脂类，每个蛋白质分子可以与27-34个酸性脂类分子结合。在pH 7.4时，碱性蛋白质有38个碱性残基；因此，几乎所有的碱性残基都可以参与与酸性脂类极性基团的静电结合，导致脂类相分离。
Differential scanning calorimetry was used to detect lipid phase separation induced in mixtures of acidic and neutral phospholipids by myelin basic protein from human CNS myelin. Phosphatidic acid, phosphatidylglycerol and phosphatidylserine mixtures with phosphatidylcholine (PC) were used and were nearly randomly mixed in the absence of the protein. Incorporation of basic protein into these mixtures caused a shift in the phase transition temperature toward the temperature of the PC component, indicating that it binds and separates out the acidic lipid leaving a PC-enriched phase. In some cases a transition due to the acidic lipid-basic protein complex was also observed. The shift towards the transition temperature of the PC component occurred regardless of whether the PC was the lower melting or the higher melting component of the mixture. The protein did not just bind to the lipid which melts first, but bound to the acidic lipid even if it melts at a much higher temperature than the neutral lipid. If enough acidic lipid was available, the protein could bind to 27-34 molecules of acidic lipid per molecule of protein. At pH 7.4 basic protein has 38 basic residues; thus, nearly all of these can be involved in electrostatic binding to acidic lipid polar head groups resulting in lipid phase separation.