细胞色素f在光合膜上功能的初步探讨

用阳离子一竭尽的菠菜叶绿体膜作为实验材料,比较研究了胰蛋白酶消化的叶绿体膜和非消化的叶绿体膜的四阶导数吸收光谱、细胞色素f的还原减氧化差异光谱和电子传递速率的变化,试图探索细胞色素f在光合膜上的功能.主要结果于下:(1)胰蛋白酶消化引起叶绿体膜四阶导数吸收光谱位于554nm吸收峰(CYT.f的特征吸收峰)下降和细胞色素含量的明显减少.说明胰蛋白酶损伤细胞色素f.(2)胰蛋白酶消化对叶绿体膜从DCIPH_2到甲基紫精的非循环式电子传递速率没有影响,而对PMS存在下的甲基紫精光还原速率有明显的刺激作用.说明胰蛋白酶损伤与循环式电子流有关的细胞色素f.根据试验结果的分析.我们推测,在光合膜上可能存在两种类型的细胞色素f.一种可能与循环式电子流有关.另一种可能与非循环式电子流有关.

INITIAL EXPLORATION OF THE FUNCTION ABOUT THE CYTOCHROME f IN CHLOROPLAST MEMBRANES

The fourth derivative absorption spectra, difference spectra(HQ-reduced minus Fecy oxidized)of cytochrome f and non-cyclic and cyclic electron tra nsport rates have been investigated in trypsin treated and normal cation-depleted spinach chloroplst membranes.The absorption peak at wavelength near 554 nm of the fourth derivative spectrum depressed after trypsin digestion.similar results are obtained in difference spectrum measurements of cytochrome f.The result with SDS-PAGE shows that polypeptide in 34 KP was partly lost after trypsin treatment.Trypsin damags at least 13% or more of total cytochrome f.The effects of trypsin on non-cyclic and cyclic electron transpors rates are compared in an attempt to discern the site of action of the 13% of cytochrome f on the chloroplast membranes. The result indicates that cyclic electron transport is sensitive to trypsin.These results are considered in terms of organizational aspects of cytochrome f in chloroplast membranes.