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Thylakoid polypeptide components, Mg~(2+) -induced Chl a fluorescence at 77K and surface chargechanges were measured to investigate the functional sites of Mg~(2+) in the regulation of energy distri-bution between two photosystems in completely and incompletely developed barley chloroplasts. It wasfound that in contrast to the completely developed chloroplasts, the incompletely developed chloroplastslacked Chl b and did not contain the 23KDa and 25KDa polypeptide components of LHC-PSII. In themeantime, these membranes did nor present Mg~(2+) -induced Cbl a fluorescence and surface charge changesof thylakoids. These results provided strong evidence that the 23KDa and 25KDa polypeptides ofLHC-PSII are the specific acting sites of the cation that induced these two phenomena. It is suggested in this paper that Mg~(2+) -induced change of excitation energy distribution betweentwo photosystems is produced by the mechanism due to electrostatic neutralization of LHC-PSII bythe cation to cause a structural or con 相似文献
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关于软硬酸碱原则(HSAB)在有机化学上的应用,已有不少论述。但对其定量标度尚很少取得进展。徐辉碧和龙耀庭扩展了刘祁涛提出的用电负性(x)和离子势(z/r)两个键参数对HSAB原则进行定量标度的概念,尝试用诱导效应指数代替电负性以及应用电荷与非球形离子热化学半径比,作为键参数,计算了十七种复杂无机离子的酸碱软硬度值。 相似文献
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刺松藻类囊体膜23kD和24kD多肽在阳离子调节激发能分配中的作用 总被引:1,自引:0,他引:1
与高等植物不同,Mg~(2+)诱导刺松藻类囊体膜Chla荧光F_(687)增高与其诱导膜表面电荷密度减小无平行相关性,用Ca~(2+)提去膜表面的30和31kD多肽(Q_B蛋白),对Mg~(2+)诱导上述两种效应无明显的影响,但用胰酶消化进一步除去膜表面的23和24kD多肽后,Mg~(2+)诱导F_(687)增高的效应随之消失,而诱导膜表面电荷密度变化的性质不变,这些结果证明,刺松藻类囊体膜表面的23和24kD多肽是Mg~(2+)诱导荧光变化的功能部位;Mg~(2+)诱导激发能分配的改变不受膜表面静电性质控制。 相似文献
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本文用胰蛋白酶作探针研究了菠菜叶绿体膜结构与功能之间的关系.在胰蛋白酶消化过的叶绿体中,观察到低浓度的CCCP(10μM)对放O2和电子传递速度有强烈的抑制作用.胰蛋白酶诱导的这类CCCP的抑制作用,可被牛血清蛋白所“阻滞”.牛血清蛋白可使胰蛋白酶消化引起的叶绿体光还原DCIP的抑制得到恢复,但对酶消化产生的放O2抑制无恢复效果. 根据上述结果推论:在PS-Ⅱ膜上可能存在有类似“通道”和“门”的结构;囊状体膜上的蛋白质组分有微区域的差异. 相似文献
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冠醚存在下,氯仿和水合肼反应制取重氮甲烷已有报导,但冠醚类毒性较大,而季铵盐易于制备,价格便宜。本文以自制的苄基三乙基氯化铵代替冠醚作为相转移催化剂进行该α-消去反应,制取重氮甲烷。本法的优点是可以不通过致癌物质N-亚硝基化合物,反应条件温和,操作简便安全,反应时间较短,其收率较Sepp等人用 相似文献
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在二甲基亚砜-丙酮-水溶液中研究硫氰酸钼(Ⅴ)配合物 总被引:3,自引:0,他引:3
前已报道,在二甲基亚砜(DMSO)-丙酮混合溶剂中,硫氰酸钴(Ⅱ)配合物可以被稳定化.本文报道DMSO-丙酮混合溶剂对硫氰酸钼(Ⅴ)配合物的稳定化作用,并试图进一步研究硫氰酸钼(Ⅴ)配合物的生成机理.最近,林谦次郎等研究了Triton X-100非离子表面活性剂(0.8%)对黄橙色硫氰酸钼(Ⅴ)配合物的稳定化和增敏作用(ε=1.72×10~4),但未涉及混合有机溶剂的作用.我们发现:在50mL溶液fp,含5mL 30%(w/v)DMSO的丙酮溶液,7.5mL1∶1 H_2SO_4,4mL 1∶1 HClO_4,3mg铁和4mL 6%抗坏血酸,硫氰酸钼(Ⅴ)配合物(Mo:0~200μg)至少可稳定4小时,ε=1.31×10~4(λ=468nm).特别有兴趣的是:混合溶剂中的 相似文献
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The effects of trypsin on the light-induced variable fluorescence of both the normaland tris-washed spinach chloroplasts have been investigated and it is discovered that: (i)Trypsin clearly inhibits in both cases the light-induced variable fluorescence emissions;but when the exogenous electron donor SMC B is added, this inhibitroy effects of trypsinare greatly alleviated and the recovery efficiency is similar in both cases. (ii) In thepresence of DCMU, trypsin still inhibits the variable fluorescence intensity but theexogenous electron acceptor such as DCIP or Fecy has no influence on it. Based on the above results, the following conclusion can be drawn: trypsin can evident-ly inactivate the electron transport on the oxidizing side of PS-Ⅱ, which exists between thewater splitting enzyme system and SMCB binding site. However, the water splitting enzymeis not sensitive to trypsin. It might be assumed that there is some protein on the thylakoidmembrane that acts as regulator to the functional mechanism of 相似文献
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在溶剂萃取分离中,多次萃取率是一个常用的实验量,用来表示萃取物的重量百分比。对多次萃取率的计算一般可采用下式其中第一次萃取平衡后水相吸光度才的函数。才.和刀值用分光光度计测出后,在吸光度值与被萃取物浓度服从线性关系范围内,即可采用(们式计算多次萃取率 相似文献