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| 題名: | Enzyme-catalyzed hydrolysis of the supported phospholipid bilayers studied by atomic force microscopy |
| 作者: | 姚學麟;Wu, HengLiang;Yu, Le;Tong, Yujin;Ge, Aimin;Yau, Shuehlin;Osawa, Masatoshi;Ye, Shen |
| 貢獻者: | 理學院化學學系 |
| 關鍵詞: | 1,2-Dipalmitoylphosphatidylcholine;1,2-Dipalmitoylphosphatidylcholine - chemistry;Aluminum Silicates;Aluminum Silicates - chemistry;Atomic force microscopy (AFM);Bee Venoms;Bee Venoms - metabolism;Biochemistry;Biophysics;Cell Biology;Cell membrane;Enzyme reaction;Enzymes;Enzymes - chemistry;Hydrolysis;Kinetics;Kinetics and mechanism;Lipid Bilayers;Lipid Bilayers - chemistry;Lipids;Lipids - chemistry;Microscopy, Atomic Force;Microscopy, Atomic Force - methods;Phospholipase A2 (PLA2);Phospholipases A2;Phospholipases A2 - chemistry;Phospholipids;Phospholipids - chemistry;Stereoisomerism;Supported lipid bilayer;Temperature;Time Factors |
| 日期: | 2013-02-01 |
| 上傳時間: | 2026-04-21 14:06:24 (UTC+8) |
| 出版者: | Elsevier;Netherlands: Elsevier B.V |
| 摘要: | 摘要： Atomic force microscopy (AFM) is employed to reveal the morphological changes of the supported phospholipid bilayers hydrolyzed by a phospholipase A2 (PLA2) enzyme in a buffer solution at room temperature. Based on the high catalytic selectivity of PLA2 toward l-enantiomer phospholipids, five kinds of supported bilayers made of l- and d-dipalmitoylphosphatidylcholines (DPPC), including l-DPPC (upper leaflet adjacent to solution)/l-DPPC (bottom leaflet) (or l/l in short), l/d, d/l, d/d, and racemic ld/ld, were prepared on a mica surface in gel-phase, to explicate the kinetics and mechanism of the enzyme-induced hydrolysis reaction in detail. AFM observations for the l/l bilayer show that the hydrolysis rate for l-DPPC is significantly increased by PLA2 and most of the hydrolysis products desorb from substrate surface in 40min. As d-enantiomers are included in the bilayer, the hydrolysis rate is largely decreased in comparison with the l/l bilayer. The time used to hydrolyze the as-prepared bilayers by PLA2 increases in the sequence of l/l, l/d, ld/ld, and d/l (d/d is inert to the enzyme action). d-enantiomers in the enantiomer hybrid bilayers remain on the mica surface at the end of the hydrolysis reaction. It was confirmed that the hydrolysis reaction catalyzed by PLA2 preferentially occurs at the edges of pits or defects on the bilayer surface. The bilayer structures are preserved during the hydrolysis process. Based on these observations, a novel kinetics model is proposed to quantitatively account for the PLA2-catalyzed hydrolysis of the supported phospholipid bilayers. The model simulation demonstrates that PLA2 mainly binds with lipids at the perimeter of defects in the upper leaflet and leads to a hydrolysis reaction, yielding species soluble to the solution phase. The lipid molecules underneath subsequently flip up to the upper leaflet to maintain the hydrophilicity of the bilayer structure. Our analysis shows that d-enantiomers in the hybrid bilayers considerably reduce the hydrolysis rate by its ineffective binding with PLA2. [Display omitted] ► Hydrolysis of a DPPC bilayer catalyzed by PLA2 enzyme is studied by AFM and simulation. ► Hydrolysis products are desorbed while lipid bilayer structures are preserved during the reaction. ► Lipid enantiomers are employed to analyze kinetics and mechanism for the PLA2-catalyzed hydrolysis reaction. ► Enzyme-induced flip-up process plays important roles in the hydrolysis reaction.
其他題名： Biochim Biophys Acta
出版者： Netherlands: Elsevier B.V
出版日期： 2013-02
出處： Biochimica et Biophysica Acta (BBA) - Biomembranes, 2013-02, Vol.1828 (2), p.642-651
資源來源： Access articles in the ScienceDirect collection
版權： 2012 Elsevier B.V.
版權： Copyright © 2012 Elsevier B.V. All rights reserved.
識別號： ISSN: 0005-2736
識別號： ISSN: 0006-3002
識別號： EISSN: 1879-2642
識別號： DOI: 10.1016/j.bbamem.2012.09.010
識別號： PMID: 22995243 |
| 顯示於類別: | [化學學系] 期刊論文
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