盐酸胍对叶绿体膜能量传递的影响

EFFECT OF GUANIDINE HYDROCHLORIDE ON ENERGY TRANSFER OF CHLOROPLAST MEMBRANES

经盐酸胍处理的菠菜叶绿体膜,在室温下的F_(685)荧光强度随盐酸胍浓发的增加而逐渐下降;荧光激发光谱中位于420nm、437nm和685nm的荧光峰高随盐酸胍浓度的增加而减小。盐酸胍处理导致叶绿体膜F_(685)/F_9736)比值下降,并且消除Mg^(+2)对激发能分配的调节作用。盐酸胍处理对叶绿体膜的吸收光谱(400～700nm)及叶绿素解离无影响,但引起叶绿体膜紫外差示光谱(处理的膜减正常的膜)中位于227nm吸收峰的出现,并且峰的吸收强度随盐酸胍浓度的增加而增强,峰位随盐酸胍浓度增加而红移。上结果表明,盐酸胍诱导的F_(685)下降,可能是盐酸胍改变膜蛋白构型,从而导致激以发能从光系统Ⅱ向光系统Ⅰ分配的结果。

The cffccts of guanidine hydrochlorde (GuHCl) on F_(685) emission of spinach chloroplast membranes have been investigated. The results have been found as follows: 1. GuHCl decreased F_(685) emission of chloroplast membranes and the decline was the function of GuHC1 concentration. The peaks at 420nm, 437nm and 485nm in fluorescence excitation spectrum decreased with the increasing concentrations of GuHCl. 2. GuHC1 had only very little effect on the absorption spectra (400—720nm)and chlorophyll contents of chloroplast membranes. 3. GuHCl resulted in F_(686)/F_(736) decline of chloroplast membranes and abolished the change of Mg^(+2)-induced fluorescence. 4. The ultraviolet difference spectra (treated membranes minus normal membranes) showed a peak at 227nm and the peak heigh increased with the increasing concentrations of GuHCl, and the position of this peak red-shifted with the increasing concentrations of GuHCl. From the above mentioned, it suggested that the confor-mation change of membrane protein induced by GuHCl resulted in excitation energy distribution from PSⅡ to PSⅠ.