Crystallization of synthetic haemozoin (beta-haematin) nucleated at the surface of lipid particles.
Crystallization of synthetic haemozoin (beta-haematin) nucleated at the surface of lipid particles.
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DOI：
10.1039/b914359a
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发表时间：
2010-02-07
期刊：
影响因子：
--
通讯作者：
Egan TJ
中科院分区：
文献类型：
--
作者：
Hoang AN;Ncokazi KK;de Villiers KA;Wright DW;Egan TJ
疟原虫色素是几种吸血生物（包括疟原虫）的解毒副产品，其形成机制一直存在争议;然而，最近的研究表明，中性脂质可能是一种催化剂。在这项研究中，由中性脂质颗粒的乳液组成的模型系统被用来研究在脂质-水界面处的β-血红素（血色素的合成对应物）的形成。将溶解在丙酮和甲醇中的甘油单酯（单硬脂酰甘油（MSG）或棕榈酰甘油（MPG））的溶液引入到水性表面。从表面下方获得的样品的荧光、共聚焦和透射电子显微镜（TEM）成像和动态光散射分析证实了存在于两个主要群体中的均质脂质颗粒的存在：一个在低微米尺寸范围内，另一个在数百纳米范围内。在仿生条件（37 °C，pH 4.8）下将血红素（Fe（III）PPIX）引入该脂质颗粒系统产生具有表观一级动力学和0.5分钟平均半衰期的β-血红素。挤出通过200 nm过滤器的单酸甘油酯（MSG或MPG）的TEM，其中血红素产生的β-血红素晶体与脂质/水界面对齐并平行。这些TEM数据，连同使用月桂酸甲酯或二十二烷的含水有机溶剂界面替换脂质的模型系统一起证明，OH和C=O基团显然是有效成核所必需的。这表明β-高铁血红蛋白通过Fe（III）PPIX与极性头基的相互作用在脂质-水界面通过外延成核而结晶。一旦成核，晶体平行于界面生长，直到生长被脂质颗粒的曲率终止。成熟晶体的疏水性质有利于内部运输，导致晶体平行于脂质-水界面和彼此排列，与疟疾寄生虫中所见惊人相似。
The mechanism of formation of haemozoin, a detoxification by-product of several blood-feeding organisms including malaria parasites, has been a subject of debate; however, recent studies suggest that neutral lipids may serve as a catalyst. In this study, a model system consisting of an emulsion of neutral lipid particles was employed to investigate the formation of β-haematin, the synthetic counterpart of haemozoin, at the lipid-water interface. A solution of monoglyceride, either monostearoylglycerol (MSG) or monopalmitoylglycerol (MPG), dissolved in acetone and methanol was introduced to an aqueous surface. Fluorescence, confocal and transmission electron microscopic (TEM) imaging and dynamic light scattering analysis of samples obtained from beneath the surface confirmed the presence of homogeneous lipid particles existing in two major populations: one in the low micrometer size range and the other in the hundred nanometre range. The introduction of haem (Fe(III)PPIX) to this lipid particle system under biomimetic conditions (37 °C, pH 4.8) produced β-haematin with apparent first order kinetics and an average half life of 0.5 min. TEM of monoglycerides (MSG or MPG) extruded through a 200 nm filter with haem produced β-haematin crystals aligned and parallel to the lipid/water interface. These TEM data, together with a model system replacing the lipid with an aqueous organic solvent interface using either methyl laurate or docosane demonstrated that the OH and C=O groups are apparently necessary for efficient nucleation. This suggests that β-haematin crystallizes via epitaxial nucleation at the lipid-water interface through interaction of Fe(III)PPIX with the polar head group. Once nucleated, the crystal grows parallel to the interface until growth is terminated by the curvature of the lipid particle. The hydrophobic nature of the mature crystal favours an interior transport resulting in crystals aligned parallel to the lipid-water interface and each other, strikingly similar to that seen in malaria parasites.
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影响因子：
2.9
作者：
Ncokazi, KK;Egan, TJ
通讯作者：
Egan, TJ
DOI：
10.1016/s0006-291x(03)01465-7
发表时间：
2003-09-05
影响因子：
3.1
作者：
Pandey, AV;Babbarwal, VK;Chauhan, VS
通讯作者：
Chauhan, VS
影响因子：
3.8
作者：
Buller, R;Peterson, ML;Leiserowitz, L
通讯作者：
Leiserowitz, L
影响因子：
3.8
作者：
de Villiers, Katherine A.;Osipova, Maria;Leiserowitz, Leslie
通讯作者：
Leiserowitz, Leslie
影响因子：
3.5
作者：
Egan, Timothy J.;Chen, Jeff Y-J.;Wood, Bayden R.
通讯作者：
Wood, Bayden R.