Membrane curvature stress controls the maximal conversion of violaxanthin to zeaxanthin in the violaxanthin cycle--influence of alpha-tocopherol, cetylethers, linolenic acid, and temperature.
Membrane curvature stress controls the maximal conversion of violaxanthin to zeaxanthin in the violaxanthin cycle--influence of alpha-tocopherol, cetylethers, linolenic acid, and temperature.
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膜曲率应力控制紫黄质循环中紫黄质向玉米黄质的最大转化——α-生育酚、鲸蜡基醚、亚麻酸和温度的影响。
DOI：
10.1016/j.bbamem.2007.06.001
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
H. Akerlund
中科院分区：
文献类型：
--
作者：
Anna Szilágyi;M. Sommarin;H. Akerlund
玉米黄质是高等植物抗过度兴奋的重要成分，是由紫黄质通过紫黄质去环氧酶形成的。我们研究了可能控制紫黄质循环中最大转化程度的因素。在不同温度和脂质包装改性剂的作用下，研究了分离的菠菜类囊体中紫黄质向玉米黄质的转化。在4°C、25°C和37°C时，最大转化率分别为35%、70%和80%。在已知促进非层状结构（HII）的膜改性剂（如亚麻酸）的存在下，转化率提高，获得的紫黄质去环氧化的最大水平接近100%。相反，促进层状相（Lα）的物质，如α-生育酚和8-十六烷基醚（C16EO8），在25℃下分别只有55%和35%的紫黄质转化。这些结果是根据类囊体膜的脂质组成来解释的，我们提出了一个模型，其中类囊体脂质双分子层中的负曲率弹性应力是紫黄素去环氧酶活性所必需的。在这个模型中，玉米黄质具有较长的疏水拉伸，可以促进膜的层状排列。结果，玉米黄质减轻了弯曲弹性应力，从而导致紫黄质去环氧化酶失活。
Zeaxanthin, an important component in protection against overexcitation in higher plants, is formed from violaxanthin by the enzyme violaxanthin de-epoxidase. We have investigated factors that may control the maximal degree of conversion in the violaxanthin cycle. The conversion of violaxanthin to zeaxanthin in isolated spinach thylakoids was followed at different temperatures and in the presence of lipid packing modifiers. The maximum degree of conversion was found to be 35%, 70% and 80% at 4 °C, 25 °C and 37 °C respectively. In the presence of membrane modifying agents, known to promote non-lamellar structures (HII), such as linolenic acid the conversion increased, and the maximal level of violaxanthin de-epoxidation obtained was close to 100%. In contrast, substances promoting lamellar phases (Lα), such as α-tocopherol and 8-cetylether (C16EO8), only 55% and 35% of the violaxanthin was converted at 25 °C, respectively. The results are interpreted in light of the lipid composition of the thylakoid membrane, and we propose a model where a negative curvature elastic stress in the thylakoid lipid bilayer is required for violaxanthin de-epoxidase activity. In this model zeaxanthin with its longer hydrophobic stretch is proposed to promote lamellar arrangements of the membrane. As a result, zeaxanthin relieves the curvature elastic stress, which in turn leads to inactivation of violaxanthin de-epoxidase.
DOI：
10.1073/pnas.160260697
发表时间：
2000-08-01
影响因子：
11.1
作者：
Attard, GS;Templer, RH;Jackowski, S
通讯作者：
Jackowski, S
影响因子：
2.9
作者：
GIBSON, NJ;BROWN, MF
通讯作者：
BROWN, MF