Cucumber cotyledon lipoxygenase oxygenizes trilinolein at the lipid/water interface
Cucumber cotyledon lipoxygenase oxygenizes trilinolein at the lipid/water interface
复制标题
黄瓜子叶脂氧合酶在脂质/水界面氧化三亚油酸
作者：
K. Matsui;T. Kajiwara
研究了黄瓜子叶脂肪氧合酶与三亚油酸甘油酯的反应性。酶对亚油酸的活性随着测定溶液pH的增加而迅速降低，并且在pH 8.5以上基本上检测不到活性。活性的快速降低不是酶在碱性pH下失活的结果，因为对于三亚油酸甘油酯，酶显示出宽的pH-活性曲线，并且即使在pH 9.0下也可以检测到大量的活性。相反，活性的降低是由于亚油酸乳液解离成酸皂聚集体和/或单体形式，这取决于末端羧基的电离。这表明，黄瓜子叶脂氧合酶只作用于脂/水界面上的不溶性底物，而不作用于可溶性底物。从三亚油酸甘油酯形成的产物的高效液相色谱分析显示，该酶插入到三亚油酸甘油酯的酰基部分的氧，而不水解的酯键。预孵育的酶与三油酸甘油酯乳液有效地消除了它的活性对三亚油酸甘油酯后加入。此外，酶以基本上不可逆的方式吸附在三亚油酸甘油酯或三油酸甘油酯乳液液滴上。该酶与三亚油酸甘油酯的反应速度曲线呈饱和动力学。这被认为是由于反应进行时区域底物不足。这些证据表明，酶，一旦结合到脂质/水界面，是不能打破自由和结合到其他乳液。
The reactivity of cucumber cotyledon lipoxygenase with trilinolein was examined. The activity of the enzyme against linoleic acid rapidly decreased with increasing pH of the assay solution, and essentially no activity could be detected above pH 8.5. The rapid decrease in activity was not the result of an inactiveness of the enzyme at alkaline pH, because with trilinolein, the enzyme showed a broad pH-activity profile, and substantial activity could be detected even at pH 9.0. Rather, the decrease in activity was due to the dissociation of the linoleic acid emulsion into acid-soap aggregates and/or the monomeric form, depending on the ionization of the terminal carboxylic group. This suggests that cucumber cotyledon lipoxygenase acts only on an insoluble substrate at the lipid/water interface but not on a soluble one. High-performance liquid chromatography analyses of the products formed from trilinolein revealed that the enzyme inserted oxygen into the acyl moiety of trilinolein without hydrolysis of the ester bonds. Preincubation of the enzyme with triolein emulsions effectively abolished its activity against trilinolein added afterward. Furthermore, the enzyme was adsorbed on the trilinolein or triolein emulsion droplets in an essentially irreversible manner. A reaction velocity curve of the enzyme with trilinolein showed saturation kinetics. This is thought to be due to a regional substrate deficiency as the reaction proceeds. These lines of evidence indicate that the enzyme, once bound to the lipid/water interface, is unable to break free and bind to other emulsions.
登录
查看更多内容
分泌型磷脂酶 A2 N 端片段在界面处的构象动力学的功能意义。
影响因子：
2.9
作者：
Maliwal,BP;Yu,BZ;Szmacinski,H;Squier,T;vanBinsbergen,J;Slotboom,AJ;Jain,MK
通讯作者：
Jain,MK
脂蛋白脂肪酶结构域的功能。
DOI：
--
发表时间：
1994
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Wong,H;Davis,RC;Thuren,T;Goers,JW;Nikazy,J;Waite,M;Schotz,MC
通讯作者：
Schotz,MC
影响因子：
2.9
作者：
BRASH, AR;INGRAM, CD;HARRIS, TM
通讯作者：
HARRIS, TM
磷脂酶 A2 催化的囊泡水解：在快速模式中使用界面催化。
影响因子：
--
作者：
Jain,MK;Gelb,MH
通讯作者：
Gelb,MH
影响因子：
56.9
作者：
BOYINGTON, JC;GAFFNEY, BJ;AMZEL, LM
通讯作者：
AMZEL, LM