Oxygen permeability of thylakoid membranes: electron paramagnetic resonance spin labeling study.
Oxygen permeability of thylakoid membranes: electron paramagnetic resonance spin labeling study.
复制标题
类囊体膜的氧渗透性：电子顺磁共振自旋标记研究。
DOI：
10.1016/s0005-2728(98)00098-x
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Subczynski,WK
中科院分区：
文献类型：
--
作者：
Ligeza,A;Tikhonov,AN;Hyde,JS;Subczynski,WK
利用电子顺磁共振谱（EPR）研究了菠菜（Spinaciaoleracea）叶绿体类囊体膜中氧的运输。硬脂酸自旋标记用于探测局部氧扩散-浓度产物。的自由基部分位于不同的距离从膜表面，碰撞率估计从EPR光谱的线宽测量的存在和不存在的分子氧。在20°C下测定的跨膜的局部氧扩散-浓度乘积的曲线表明，在所有膜位置处，该乘积高于在水中测量的值。根据氧扩散-浓度乘积的分布，使用早先开发的程序（W.K. Subczynski，J.S.海德，A。Kusumi，Proc. Natl. Acad. Sci. USA 86（1989）4474-4478）。在20°C时，类囊体膜脂质部分的透氧系数为39.5 cm s-1。该值比与类囊体膜相同厚度的水层的透氧系数高20%。高渗透系数意味着在饱和光化光照射下产生的跨类囊体膜的氧浓度差可以忽略不计，小于1 μM。
Oxygen transport in thylakoid membranes of spinach chloroplasts (Spinacia oleracea) has been studied by observing the collisions of molecular oxygen with spin labels, using line broadening electron paramagnetic resonance (EPR) spectroscopy. Stearic acid spin labels were used to probe the local oxygen diffusion–concentration product. The free radical moiety was located at various distances from the membrane surface, and collision rates were estimated from linewidths of the EPR spectra measured in the presence and absence of molecular oxygen. The profile of the local oxygen diffusion–concentration product across the membrane determined at 20°C demonstrates that this product, at all membrane locations, is higher than the value measured in water. From the profile of the oxygen diffusion–concentration product, the membrane oxygen permeability coefficient has been estimated using the procedure developed earlier (W.K. Subczynski, J.S. Hyde, A. Kusumi, Proc. Natl. Acad. Sci. USA 86 (1989) 4474–4478). At 20°C, the oxygen permeability coefficient for the lipid portion of the thylakoid membrane was found to be 39.5 cm s−1. This value is 20% higher than the oxygen permeability coefficient of a water layer of the same thickness as the thylakoid membrane. The high permeability coefficient implies that the oxygen concentration difference across the thylakoid membrane generated under the illumination of the leaf by saturating actinic light is negligible, smaller than 1 μM.