Facilitated phosphatidylcholine flip-flop across erythrocyte membranes using low molecular weight synthetic translocases
Facilitated phosphatidylcholine flip-flop across erythrocyte membranes using low molecular weight synthetic translocases
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DOI：
10.1021/ja010160q
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发表时间：
2001-07-04
影响因子：
15
通讯作者：
Smith, BD
中科院分区：
文献类型：
--
作者：
Boon, JM;Smith, BD
磷脂的跨膜分布在人的红细胞中起着重要的调节作用。膜结合的转位酶通过促进跨膜扩散或触发来维持磷脂在膜单层上的不对称分布。在分子水平上，对触发器过程的机械理解是薄弱的。最近，我们发现三(氨基乙基)胺的酰胺和磺胺类化合物促进了磷脂在囊泡膜上的翻转；也就是说，它们作为低分子量的合成转位酶。在这份报告中，核磁共振证据表明，合成的转位酶通过与磷胆碱头基形成氢键复合体来发挥作用，该复合体降低了头基的极性，并促进了跨膜亲脂内部的扩散。此外，细胞形态和荧光探针方法也表明，这些合成的转位酶促进了磷脂酰胆碱在红细胞膜上的翻转。在红细胞中加入少量二桂酰磷脂酰胆碱可产生棘细胞形态，这种形态需要几天时间才能恢复到原始的盘状细胞形状。合成易位酶的存在显著加快了回报率。人工合成的转位酶促进了荧光磷脂酰胆碱探针1-棕榈酰基-2-(N-[7-nitrobenz-2-oxa-1，3-diazol-4-yl]aminohexanoyl)-sn-glycero(PC-NBD))的内向转位(FliP)。
The transmembrane distribution of phospholipids plays an important regulatory role in human erythrocytes. Membrane-bound translocase enzymes maintain an asymmetric phospholipid distribution across the membrane monolayers by promoting transmembrane diffusion or flip-flop. Mechanistic understanding of the flip-flop process is weak at the molecular level. Recently, we discovered that amide and sulfonamide derivatives of tris(aminoethyl)amine facilitate phospholipid flip-flop across vesicle membranes; that is, they act as low molecular weight, synthetic translocases. In this report, NMR evidence is provided that suggests that the synthetic translocases work by forming a hydrogen-bonded complex with the phosphocholine headgroup which decreases headgroup polarity and promotes diffusion across the lipophilic interior of the membrane. Also cell morphology and fluorescence probe methods are used to show that these synthetic translocases facilitate phosphatidylcholine flip-flop across erythrocyte membranes. Addition of a small amount of dilauroylphosphatidylcholine to erythrocytes produces echinocyte morphology which takes days to revert back to the original discocyte shape. The rate of return is significantly accelerated by the presence of the synthetic translocases. The synthetic translocases facilitate inward-translocation (flip) of the fluorescent phosphatidylcholine probe, 1-palmitoyl-2-(N- [7-nitrobenz-2-oxa-1,3-diazol-4-yl]aminohexanoyl)-sn-glycero (PC-NBD).