从超声波破碎的蓝藻类囊体膜中分离的叶绿素蛋白复合物

THE CHLOROPHYLL-PROTEIN COMPLEXES RESOLVED FROM ULTRASONICALLY BROKEN THYLAKOID MEMBRANES OF BLUE-GREEN ALGAE

当蓝藻的类囊体膜用超声波进行破碎,并在4℃下用聚丙烯酰胺凝胶电泳进行分离,有6条叶绿素带被分离出来,它们分别是 CPIa,CPIb,CP1,CPa1 CPa2,FC。CP1 在红区和蓝区的吸收峰分别位于674和435 nm 处。在液氮甲该组分在725和680 nm 处有两个荧光发射带。CPa1和 CPa2的吸收光谱相似,其红峰和蓝峰的位置分别位于667和431.5nm 处。它们在77 K 的荧光发射峰都位于684 nm 处。用超声破碎法分离的叶绿素蛋白复合物的光谱特性,除 CPa1和 CPa2在红峰和蓝峰的吸收位置蓝移了3—5 nm 之外,其余与用 SDS 增溶法分离的相应复合物相似。属于光系统Ⅰ的 CPIa-CPI 的叶绿素含量占总叶绿素的40.93%,而属于光系统Ⅱ的 CPa1和 CPa2的叶绿素则占总叶绿素的38.78%,二者之差仅有2.15%。

When the thylakoid membranes of blue-green algae were broken by ultrasonic vibrations and subjected to polyacrylamide gel electrophoresis at 4℃,six green zones were resolved.They were designated as CPIa,CPIb, CPI,CPa1,CPa2,and FC.The absorption spectrum of CPI had a red maximum at 674 nm and a peak in the blue at 435 nm.It was identified as PS-Ⅰ chlor- ophyll a-protein complex,but was contaminated with minor PS-Ⅱ which was implied by the appearance of fluorescence emission peak at 680 nm besides the main one at'725 nm at 77K. The spectral properties of CPIa and CPIb were similar to that of CPI.The absorption spectra of CPa1 and CPa2 were similar,both having red maxima at 667 nm and peaks in the blue at 431.5 nm.Their fluorescence emission had the same peaks at 684 nm at 77 K indicating that they belonged to PS-II.It was recognized that CPal of 47 kD is the reaction center complex of photo- system Ⅱ and CPa2 of 40 kD is the internal antenna complex of photosystem Ⅱ.The spectral characteristics of the chlorophyll-protein complexes resolved by ultrasonic method were similar to those of the same complexes resolved by SDS solubilization,except the absorbance positions of CPa1 and CPa2 in the blue peak and the red one which shifted to blue about 3—5 nm.It was cal- culated that in thylakoid membranes of blue-green algae 40.93% chlorophyll was in PS-Ⅰ, while 38.78% of chlorophyll in PS-Ⅱ.The difference of chlorophyll contents between PS-Ⅰ and PS-Ⅱ was only 2.15%.Concerning the fact that minor PS-Ⅱ compound remained in the part of PS-Ⅰ zones,it might be concluded that the distribution of chlorophyll between PS-Ⅰ and PS- Ⅱ in blue-green algae was equal.This result was in agreement with the hypothesis that PS-I and PS-Ⅱ operates in series in photosynthetic electron transport.