Mg~(2 )诱导 Chla 荧光,膜垛迭和膜表面电荷变化之间的关系

利用低盐介质分离的冀北1号大豆叶绿体膜,同时测定不同浓度 Mg~(2 )对 Chla 可变荧光产率,类囊体膜再垛迭和膜电泳速率的影响。现察到 Mg~(2 )抑制膜电泳迁移率与其刺激 Chla可变荧光产率及膜再垛迭之间,存在有良好的相关性,证实金属阳离子对激发能在两个光系统之间传递与分配的调节作用,与金属阳离子中和或屏蔽类囊体膜表面的净负电荷,促使膜再垛迭密切相关。     

叶绿体膜的结构和功能——ⅩⅣ.发育完善与发育不完善的叶绿体膜的某些荧光与延迟光特性的比较

用动力学分光光度计,测定和比较了发育完善与发育不完善小麦叶绿体膜的可变荧光(Fv)、固定荧光(Fo)及延迟光(D.L.)的一些特性、结果是:1.发育不完善叶绿体膜比发育完善的叶绿体膜有较强的Fo发射。2.发育完善的叶绿体膜加Mg~(2+)后,通常表现出Fv的显著增加,而发育不完善膜无Mg~(2+)的调节作用。3.发育不完善叶绿体膜的Fv上升时间约比发育完善的叶绿体膜慢1个数量级、而且,发育不完善膜的光合单位约为对照的1/7.4。4.发育不完善叶绿体膜的Fv下降时间要比发育完善的叶绿体膜慢得多。5.发育不完善叶绿体膜的Fv荧光诱导时间进程曲线,呈指数关系,而发育完善的叶绿体膜的Fv的对数时间进程Log(1-Fv％)呈S型。6.发育不完善叶绿体膜的毫秒级和秒级的延迟光发射及延迟光诱导时间进程都比发育完善的叶绿体膜弱得多。     

海生植物叶绿体膜中阳离子诱导激发能分配变化的静电控制与非静电控制的研究

用Ｃａ２＋和胰酶处理大叶藻（Ｚｏｓｔｅｒａｍａｒｉｎａ）和刺松藻（Ｃｏｄｉｕｍｆｒａｇｉｌｅ）叶绿体膜,研究了它们的类囊体膜多肽组分与Ｍｇ２＋诱导Ｃｈｌａ荧光和膜表面电荷变化之间的相互关系。观察到：（１）在大叶藻的叶绿体膜中,Ｍｇ２＋诱导ＰＳ－Ⅱ荧光强度的增高与其诱导类囊体膜表面电荷密度的降低密切相关;但这种相关性的效应不存在于刺松藻的叶绿体膜中。（２）用Ｃａ２＋处理这两种叶绿体膜分别除去其类囊体膜表面的３２－３４ＫＤ和３０－３１ＫＤ多肽,对上述Ｍｇ２＋诱导的现象无明显的影响。（３）用胰酶进一步消化这些Ｃａ２＋处理过的叶绿体膜分别除去其类囊体膜表面的２６ＫＤ和２３－２４ＫＤ多肽,那么在大叶藻的叶绿体膜中,Ｍｇ２＋诱导荧光和类囊体膜表面电荷变化的相关性效应则全部消失;但在刺松藻的叶绿体膜中,Ｍｇ２＋诱导荧光增高的效应完全消失,而Ｍｇ２＋诱导膜表面电荷变化的性质则保持不变。这些实验结果不仅证明,类囊体膜表面的２６ＫＤ和２３－２４ＫＤ多肽分别为大叶藻和刺松藻叶绿体膜中阳离子诱导激发能在ＰＳ－Ⅱ和ＰＳ－Ⅰ之间分配变化的特异性作用部位;而且说明阳离子调节激发能在这两个光系统之间分配的机理,在这两种海生植物的叶绿体膜中     

关于阳离子诱导光合激发能分配改变的机理研究:23—25KD多肽在Mg~(2+)诱导Chla荧光及类囊体膜表面电荷变化中的作用

暗中培养的黄化大麦苗在25℃用连续光照射48小时,其转绿质体明显地呈现出Mg~(2+)诱导Chla低温荧光F_(685)/F_(736)比值增高和类囊体膜电泳迁移率下降,而且这两种效应具有良好的相关性.此外,利用在照光开始时,加入蛋白质合成抑制剂CAP处理所得到的转绿质体,进行了同样的实验观察,发现这种转绿质体无Mg~(2+)诱导Chla荧光及膜表面电荷改变的效应.用常规的SDS—PAGE进行类囊体膜的多肽分析表明,这种转绿质体亦缺少LHC—PSⅡ23—25KD多肽成分.这些实验结果证明,LHC—PSⅡ23—25KD多肽成分是阳离子结合的特异性部位.文中讨论了Mg~2+)对LHC—PSⅡ的静电中和作用所引起的膜空间或构型的改变,可能是阳离子诱导激发能在两个光系统之间分配变化的重要原因.     

质体醌在两个光系统激发能分配中的功能

用非极性有机溶剂正己烷抽提菠菜类囊体膜,Mg~(2+)调节激发能在两个光系统间的分配效率降低:向抽提过的类囊体膜加入人工合成的PQ类似物PQ_2,有部分恢复Mg~(2+)对能量分配的调节作用,但对类囊体膜表面静电性质不产生影响.向非抽提的类囊体膜加入二溴百里香醌(DBMIB),一种抑制PQ氧化的抑制剂,同样发现DBMIB抑制Mg~(2+)调节激发能分配的效率,但对类囊体膜表面静电性质也不发生影响.以上实验结果表明,PQ对Mg~(2+)诱导激发能在两个光系统间的分配具有调节作用.这种调节作用不依赖于类囊体膜的表面电荷变化,而与PQ的氧化还原状态密切相关.     

叶绿体膜的结构与功能 Ⅱ.钾离子和镁离子对两种类型叶绿体膜吸收光谱及光系统Ⅱ功能的影响

研究不同阳离子和不同阳离子浓度对两种类型的叶绿体膜吸收光谱和光系统Ⅱ功能的影响。观察到一价的 K~ 和二价的 Mg~(2 )对发育完善的叶绿体膜的吸收光谱具有同样的效应,它们均降低这种叶绿体在红区和蓝区的吸收峰,峰值的降低与离子浓度成正相关。而在发育不完善的叶绿体中却没有观察到类似的现象。在不同浓度的 K~ 和 Mg~(2 )的存在下,红区的吸收峰几乎完全重叠,仅在蓝区稍有变化。不同浓度的 K~ 和 Mg~(2 )对上述两种类型的叶绿体膜的 DCIP 光还原速度均有促进作用,但是它们的促进作用有相当大的差别。本文还讨论了阳离子对这两种类型叶绿体膜吸收光谱和光系统Ⅱ活力不同影响的原因。     

海生植物叶绿体膜中阳离子诱导激发能分配变化的静电控制与非静…

用Ｃａ＾２＋和胰酶处理大叶藻和剌松藻叶绿体膜，研究了它们的类囊体膜多肽组分与Ｍｇ＾２＋诱导Ｃｈｌａ荧光和膜表面电荷变化之间的相互关系。观察到：（１）在大叶藻的叶绿体膜中，Ｍｇ＾２＋诱导ＰＳ－Ⅱ荧光强度的增高与其诱导类囊体膜表面电荷密度的降低密切相关；但这种相关性的效应不存在于剌松藻的叶绿体膜中。（２）用Ｃａ＾２＋处理这两种叶绿体膜分别除去其类囊体膜表面的３２－３４ＫＤ和３０－３１ＫＤ多肽，对上述Ｍ     

阳离子诱导大叶藻叶绿体膜中激发能在PSⅡ和PSⅠ之间分配变化的机理(英文)

用Ｃａ２＋ 和胰酶处理大叶藻（Ｚｏｓｔｅｒａ ｍ ａｒｉｎａ）叶绿体膜研究了其类囊体膜多肽成分与Ｍｇ２＋ 诱导其Ｃｈｌａ荧光和类囊体膜表面电荷变化之间的相互关系,观察到：１．在正常的叶绿体膜中,Ｍｇ２＋ 诱导ＰＳⅡ荧光强度的增高与其诱导类囊体膜表面电荷密度的降低密切相关;２．用Ｃａ２＋ 处理这种叶绿体膜,除去类囊体膜表面的３２～３４ ｋＤ多肽对Ｍｇ２＋ 诱导的上述现象无影响;３．如果用胰酶消化Ｃａ２＋ 处理过的叶绿体膜,进一步除去膜表面的２６ ｋＤ多肽,Ｍｇ２＋诱导的这些现象则全部消失。这些实验结果清楚地表明,在大叶藻的叶绿体膜中,类囊体膜表面的２６ ｋＤ 多肽是阳离子诱导这两种相关现象的特异性作用部位。对阳离子调节激发能在ＰＳⅡ和ＰＳⅠ之间分配的机理进行了讨论     

Mg2+对生长在不同光强下的小麦叶绿体光合功能的影响

研究结果表明,Mg~(2+)对生长在不同光强度下的小麦叶绿体光合功能有不同影响。与生长在低光强(2×10~8勒克斯)下的小麦叶绿体相比,Mg~(2+)更加明显地降低从生长在高光强(2×10~4勒克斯)下的小麦所分离的叶绿体的吸收光谱在红区和蓝区的吸收峰值;但它更大幅度地提高后者在低温(77K)下的PSⅡ相对荧光产量(F_(687))与PSⅠ相对荧光产量(F_(742))的比值,PSⅡ活性和PSⅡ原初光能转化效率。实验结果证明,更高的光强度可能有利于叶绿体形成更多可流动的LHC-Ⅱ和LHC-Ⅰ。     

两种酪氨酸蛋白激酶活性在主动脉平滑肌细胞增殖周期中的动态变化

本文以人工合成的多肽PGAT 为底物鉴定了培养的家兔ASMC 膜性TPK。发现Mg~(2+)和Mn~(2+)对ASMC 胞浆膜性TPK 和核膜性TPK 的激活作用有两点不同:(1)它们对前者的最适激活浓度高于后者;(2)对胞浆膜性TPK,Mn~(2+)最大激活效应大于Mg~(2+)而对核膜性TPK,Mn~(2+)则低于Mg~(2+)。这两种TPK活性在其G_1期的变化特点是:胞浆膜性TPK最高活性出现在G_1晚期(9 h),核膜性TPK最高活性则出现在G_1早期(3 h)。     

Mg2+ Induced Fluorescence Change in Relation to Thylakoid Surface Electric Charge in Two Varieties of Soybean Chloroplasts

The effects of Mg2+ concentration on chlorophyll a light-in-duced variable fluorescence and eleetrophoretie velocity of chloroplasts obtained from two varieties of soybean (Ji-Pei No. 1 and Feng-Shou Yellow) were recorded. The light induced variable fluorescence yield and the eleetrophoretie mobility of two kinds of ehloroplasts in the suspending medium containing low level of salt differs from each other. But, the fluorescence yield of chloroplast membranes from two varieties of soybean is relative to that of eleetrophoretic mobility. The pattern of kinetic change of Mg2+ induced variable fluorescence intensity is similar to that of eleetrophoretie mobility. The optimum concentrations of Mg2+ required for the effect on chlorophyll fluorescence and the electrophoretie velocity change are also similar These results indicate that Mg2+ induced excitation energy distribution change between the two photosystems is intimately related to Mg2+-indueed alteration of thylakoil membrane surface eleetrostat.ie property. The possible role of earboxyl group of proteins on Mg2+ induced effects has been discussed in this paper.     

Protective Effect of Pretreatment of Spinach Chloroplasts with Mg2+ Against Trypsin

It has been shown that fluorescence yield of chloroplasts at wavelength near 684 nm can be regulated by Mg+2. But on the other hand trypsin abolishes this Mg+2-induced fluorescence change. Pretreatment of chloroplasts with Mg+2 protects the Mg+2 induced chlorophyll a fluorescence change from trypsin. It is found that the protective effect of Mg+2 pretreatment of chloroplasts against trypsin is concentration dependent (at the range btween 1.5-12 mM Mg+2). At a 12 mM MgCl2 concentration it appears that trypsin has no effect on Mg+2-induced fluorescence change. Similar results were obtained with the determination of chlorophyll contents in the chloroplasts. Plants grown at different temperature produce chloroplasts which show similar characteristics. But lower fluorescence and chlorophyll change are found in the Low temperature grown plants. The above results support the evidence that pretreating the chloroplasts with Mg+2 causes a conformafional change in LHCPs and protecting the functional group that acts as regulator to the fluorescence change against trypsin. It is also proposed that pretreatment of chloroplasts with Mg+2 also protects the connection of chlorophyll molecule with protein against trypsin in thylakoid membrane.     

Further studies of the thylakoid membrane surface charges by particle electrophoresis

1. Above pH 4.3 the outer surface of thylakoid membranes isolated from pea chloroplasts is negatively charged but below this value it carries an excess of positive charge.2. Previously the excess negative charge has been attributed to the carboxyl groups of glutamic and aspartic acid residues (Nakatani, H.Y., Barber, J. and Forrester, J.A. (1978), Biochim. Biophys. Acta 504, 215–225) and in this paper it is argued from experiments involving treatments with 1,2-cyclohexanedione that the positive charges are partly due to the guanidino group of arginine.3. The electrophoretic mobility of granal (enriched in chlorophyll b and PS II activity) and stromal (enriched in PS I activity) lamellae isolated by the French Press technique were found to be the same.4. Treatment of the pea thylakoids with trypsin or pronase, sufficient to inhibit the salt induced chlorophyll fluorescence changes, increased their electrophoretic mobility indicating that additional negative charges had been exposed at the surface.5. Polylysine treatment also inhibited the salt induced chlorophyll fluorescence changes but unlike trypsin and pronase, decreased the net negative charge on the surface.6. The isoelectric point defined as the pH which gave zero electrophoretic mobility (about 4.3) was independent of the nature of the cations in the suspending medium (monovalent vs. divalent).     

Control of excitation transfer in photosynthesis V. Correlation of membrane structure to regulation of excitation transfer between two pigment systems in isolated spinach chloroplasts

1. Changes in fluorescence yield of chlorophyll a in isolated chloroplasts have been interpreted by means of regulation of excitation transfer between two pigment systems of photosynthesis^5–7. In order to investigate the relationship between the membrane structure of chloroplasts and the regulation of excitation transfer, changes of light scattering and chlorophyll a fluorescence of isolated spinach chloroplasts were measured upon addition of cations, Mg²⁺ and Na⁺. The cations increased the intensities of both light scattering and fluorescence yield. The changes showed similar time courses and concentration dependences. These facts suggest that modification of membrane structure produced by the cations suppresses the excitation transfer between the two pigment systems.

2. In another case of structural change which is induced by light in the presence of N-methylphenazonium methosulfate, there was little correlation between light-scattering and fluorescence changes.

3. Changes in fluorescence yield induced by the addition of Mg²⁺ were measured in disintegrated chloroplasts and fractionated particles. The effects of Mg²⁺ on fluorescence were observed only in preparations of grana stacks, but not in preparations of stroma lamellae. These findings suggest that the excitation transfer is regulated between the two pigment systems located in the grana thylacoid membranes.     

Organization of the photosynthetic apparatus of the chlorina-f2 mutant of barley using chlorophyll fluorescence decay kinetics

The time-resolved chlorophyll fluorescence emission of higher plant chloroplasts monitors the primary processes of photosynthesis and reflects photosynthetic membrane organization. In the present study we compare measurements of the chlorophyll fluorescence decay kinetics of the chlorophyll-b-less chlorina-f2 barley mutant and wild-type barley to investigate the effect of alterations in thylakoid membrane composition on chlorophyll fluorescence. Our analysis characterizes the fluorescence decay of chlorina-f2 barley chloroplasts by three exponential components with lifetimes of approx. 100 ps, 400 ps and 2 ns. The majority of the chlorophyll fluorescence originates in the two faster decay components. Although photo-induced and cation-induced effects on fluorescence yields are evident, the fluorescence lifetimes are independent of the state of the Photosystem-II reaction centers and the degree of grana stacking. Wild-type barley chloroplasts also exhibit three kinetic fluorescence components, but they are distinguished from those of the chlorina-f2 chloroplasts by a slow decay component which displays cation- and photo-induced yield and lifetime changes. A comparison is presented of the kinetic analysis of the chlorina-f2 barley fluorescence to the decay kinetics previously measured for intermittent-light-grown peas (Karukstis, K. and Sauer, K. (1983) Biochim. Biophys. Acta 725, 384–393). We propose that similarities in the fluorescence decay kinetics of both species are a consequence of analogous rearrangements of the thylakoid membrane organization due to the deficiencies present in the light-harvesting chlorophyll $\text{a}\text{b}$ complex.     

Mechanism of Change in the Cation-Induced Excitation Energy Distribution Between PSⅡ and PS Ⅰ in the Chloroplast Membrane from Zostera marina

The interrelations between thylakoid polypeptide components and Mg2+-induced Chl a fluorescence and thylakoid surface charge changes were investigated in Zostera marina chloroplasts treated with Ca2+ and trypsin. It was observed that: 1. The increase of Mg2+- induced PS Ⅱ fluorescence intensity was closely related to the decrease of Mg2+-induced surface charge density of the thylakoid membrane in the normal chloroplast; 2. Removal of the 32～34 kD polypeptides of the thylakoid surface by Ca2+ extraction of the chloroplast did not affect the Mg2+-induced phenomena; 3. If the Ca2+-treated chloroplast was further digested by trypsin to remove the 26 kD polypeptide of the membrane surface, the Mg2+-induced phenomena disappeared completely. These results clearly indicated that the 26 kD polypeptide of thylakoid surface is the specific acting site of the cation that induced these two correlated phenomena in the chloroplast from Zostera marina. The mechanism on the regulating effect of the cation on excitation energy distribution between PS Ⅱ and PS Ⅰ was discussed.     

Isolation and Characterization of Photosystem Ⅱ Reaction Center D1-D2-Cytochrome b-559 Complex from the Chloroplasts of Spinach

Photosystem Ⅱ reaction center D1-D2-cytochrome b-559 pigment-protein complex has been isolated and purified from chloroplasts of spinach and its properties have been studied. The Isotared photosystem II reaction center contains close to six chlorophyll a per two pheophytin a molecules. Analysis of fluorescence decaying by phase modulation fluorometry suggests that the reaction center has three components of fluorescence decaying with lifetimes of 1.5 nS, 6.23 nS, 36.26 nS in terms of fractions to total fluorescence yield as 0.06, 0.67, 0.27 respectively. The ,6.25 nS fluorescence component corresponds to chlorophyll a which is energetically uncoupled from the process of charge separation. The proportion of 1.51 nS component is very low, and its source is unclear. The 36.25 nS fluorescence component is attributed to the recombination of the primary radical pair, and so represents the activity of charge separation.     

Properties of ATP-driven reverse electron flow in chloroplasts

1. The reverse reactions induced by coupled ATP hydrolysis were studied in spinach chloroplasts by measurements of the ATP-induced increase in chlorophyll fluorescence reflecting reverse electron flow, and of the ATP-induced decrease in 9-aminoacridine fluorescence, representing formation of the transthylakoidal proton gradient (ΔpH). ATP-driven reverse electron flow was kinetically analysed into three phases, of which only the second and third one were paralleled by corresponding phases in ΔpH formation. The rapid first phase and formation of a ΔpH occur also in the absence of the electron transfer mediator phenazine methosulfate.2. The rate and extent of the reverse reactions were measured at temperatures in the range from 0 to 30°C. The rate of formation of ΔpH and of reverse electron flow were faster at high temperatures, but the maximal extent of ΔpH and chlorophyll fluorescence increase were observed at the lowest temperature. Considering rate and extent of the ATP-stimulated reactions, a temperature optimum around 15°C was found. Light activation of the ATPase occurred throughout the range studied. At 0°C and in the presence of inorganic phosphate the activated state for ATPase was maintained for more then 10 min.3. The ATP-induced rise in chlorophyll fluorescence yield was found to be of similar magnitude as the rise induced by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), when both were measured with an extremely weak measuring beam. It is concluded, that both effects, although derived via distinctly different pathways, are limited by the same electron donating or electron accepting pool.     

Induction patterns of delayed luminescence from isolated chloroplasts. I. Response of delayed luminescence to changes in the prompt fluorescence yield

1. Using a phosphoroscope, delayed luminescence and prompt chlorophyll fluorescence from isolated chloroplasts have been compared during the induction period.2. Two distinct decay components of delayed luminescence were measured a “fast” component (from ≈1 ms to ≈6 ms) and a “slow” component (at ≈6 ms).3. The fast luminescence component often did not correlate with the fluorescence changes while the slow component significantly changed its intensity during the induction period in a manner which could usually be linearly correlated with variable portion of the fluorescence yield change.4. This correlation was evident after preillumination with far-red light or after allowing a considerable time for dark relaxation.5. The close relationship between the slow luminescence component and variable fluorescence yield was observed with a large range of light intensities and also in the presence of 3(3,4-dichlorophenyl)-1,1-dimethylurea which considerably changes the fluorescence induction kinetics.6. Valinomycin and other antibiotics reduced the amplitude of the 6 ms (slow) luminescence without affecting its relation with the fluorescence induction suggesting possibly that a constant electrical gradient exist in the dark or formed very rapidly in the light, which effects the emission intensity.7. Changes in salt levels of suspending media equally affected the amplitude of both delayed luminescence and variable fluorescence under conditions when the reduction of Q is maximal and constant.8. The results are discussed in terms of several models. It is concluded that the model of independent Photosystem II units together with photosynthetic back reaction concept is incompatible with the data. Other alternative models (the “lake” model and photosynthetic back reaction; recombination of charges in the antenna chlorophyll; the “W” hypothesis) were in closer agreement with the results.