D1/D2/Cytb-559复合物的共振拉曼光谱

光系统Ⅱ（ＰＳⅡ）反应中心Ｄ１／Ｄ２／Ｃｙｔｂ－５５９ 复合物在４８８ ｎｍ 处激发的共振拉曼光谱显示４ 个主要谱带,其峰位分别在１５３２（υ１）、１１６５（υ２）、１０１０（υ３）和９７０（υ４） ｃｍ － １处,表明ＰＳⅡ反应中心结合的β－胡萝卜素分子是全反式构型。Ｄ１／Ｄ２／Ｃｙｔｂ－５５９ 复合物的色素抽提液的拉曼光谱也显示４ 个主要的拉曼峰,其中υ４ 谱带的强度急剧下降,说明ＰＳⅡ反应中心内部结合的β－胡萝卜素分子与抽提液中自由的β－胡萝卜素分子的构象不同,而与光合细菌反应中心内部的类胡萝卜素分子的构象相似,其共轭多烯链的平面也处于扭曲状态     

从菠菜制备的47kD/D1/D2/Cyt b559 PSⅡ反应中心蛋白复合物

菠菜的PSⅡ颗粒在pH 6.0、有抗坏血酸钠及甘油存在的条件下,用Triton X-100处理后,经过DEAE-Toyopearl 650S离子交换层析柱分离,可得一个由47 kD,D1,D2及Cyt b559组成的PSⅡ反应中心蛋白复合物.纯化的蛋白质复合物在DPC存在下,具明显的光还原DGIP光化学活性,且在暗及光照条件下显示出SignalⅡ_(slow)及Signal Ⅱ_(fast)。低温吸收光谱和荧光光谱表明,复合物中只有叶绿素a存在;用有机溶剂抽提复合物的色素,采用一种灵敏的荧光分析方法并结合分光光度法进行分析,也证实了这点。此复合物有锰的存在,重要的化学成分中Chl a/Pheo a/Cyt b559/Mn原子的摩尔比为:18.4:2:0.8:0.3。这些结果表明;此复合物含有从PSⅡ第二电子供体Z到第一电子受体Q_A的完整光系统Ⅱ电子传递链的所有组分,同时也暗示复合物可能含有锰原子结合部位。为我们(Tang 1985)提出的水裂解系存在于PSⅡ反应中心系之中的观点提供了佐证。     

Photodamage to Pigment in the Photosystem Ⅱ Reaction Center D1/D2/Cytochrome b559 Complex

Strong light （800μmol photons/m^2 per s）-induced bleaching of the pigment in the isolated photosystem Ⅱ reaction center （PSII RC） under aerobic conditions （in the absence of electron donors or acceptors） was studied using high-pressure liquid chromatography （HPLC）, absorption spectra, 77K fluorescence spectra and resonance Raman spectra. Changes in pigment composition of the PSII RC as determined by HPLC after light treatment were as follows： with Increasing illumination time chlorophyll （Chl） a and β-carotene （β-car） content decreased. However, decreases in pheophytin （Pheo） could not be observed because of the mixture of the Pheo formed by degraded chlorophyll possibly. On the basis of absorption spectra, it was determined that, with a short time of illuminatlon, the initial bleaching occurred maximally at 680 nm but that with Increasing Illumination time there was a blue shift to 678 nm. It was suggested that P680 was destroyed Initially, followed by the accessory chlorophyll. The activity of P680 was almost lost after 10 mln light treatment. Moreover, the bleaching of Pheo and β-car was observed at the beginning of illumination. After Illumination, the fluorescence emission Intensity changed and the fluorescence maximum blue shifted, showing that energy transfer was disturbed. Resonance Raman spectra of the PSII RC excited at 488.0 and 514.5 nm showed four main bands, peaking at 1 527 cm^-1 （υ101）, 1 159 cm^-1 （υ2）, 1 006 cm^-1 （υ3）, 966 cm^-1 （υ4） for 488.0 nm excitation and 1 525 cm^-1 （υ1）, 1 159 cm^-1 （υ2）, 1 007 cm^-1 （υ3）, 968 cm^-1 （υ4） for 514.5 nm excitation. It was confirmed that two spectroscopically different β-car molecules exist In the PSII RC. After light treatment for 20 mln, band positions and bandwidths were unchanged. This indicates that carotenoid configuration Is not the parameter that regulates photoprotectlon in the PSII RC.     

Photodamage to Pigment in the Photosystem Ⅱ Reaction Center D1/D2/Cytochrome b559 Complex

Strong light (800 μmol photons/m2 per s)-induced bleaching of the pigment in the isolated photosystem Ⅱ reaction center (PSII RC) under aerobic conditions (in the absence of electron donors or acceptors) was studied using high-pressure liquid chromatography (HPLC), absorption spectra, 77K fluorescence spectra and resonance Raman spectra. Changes in pigment composition of the PSll RC as determined by HPLC after light treatment were as follows: with increasing illumination time chlorophyll (Chi) a and β-carotene (β-car)content decreased. However, decreases in pheophytin (Pheo) could not be observed because of the mixture of the Pheo formed by degraded chlorophyll possibly. On the basis of absorption spectra, it was determined that, with a short time of illumination, the initial bleaching occurred maximally at 680 nm but that with increasing illumination time there was a blue shift to 678 nm. It was suggested that P680 was destroyed initially, followed by the accessory chlorophyll. The activity of P680 was almost lost after 10 min light treatment. Moreover, the bleaching of Pheo and β-car was observed at the beginning of illumination.After illumination, the fluorescence emission intensity changed and the fluorescence maximum blue shifted,showing that energy transfer was disturbed. Resonance Raman spectra of the PSII RC excited at 488.0 and 514.5 nm showed four main bands, peaking at 1 527 cm-1 (υ1), 1 159 cm-1 (υ2), 1 006 cm-1 (υ3), 966 cm-1 (υ4) for 488.0 nm excitation and 1 525 cm-1 (υ1), 1 159 cm-1 (υ2), 1 007 cm-1 (υ3), 968 cm-1 (υ4) for 514.5 nm excitation.It was confirmed that two spectroscopically different β-car molecules exist in the PSII RC. After light treatment for 20 min, band positions and bandwidths were unchanged. This indicates that carotenoid configuration is not the parameter that regulates photoprotection in the PSII RC.     

CD Spectra of D1/D2/Cyt b559 Complax in Photodamaged Photosystem Ⅱ Reaction Center

The CD spectrum of photosystem Ⅱ reaction center D1/D2/Cyt b559 complex showed a strong reverse band with positive peak at 680 nm and negative peak at 660 nm in the red absorption region (Qy band). After the D1/D2/Cyt b559 complex was illuminated by strong light, the CD signals of the complex decreased significantly in the red region in which the negative peak still existed but the positive one disappeared. The result suggested that the CD signal of photosystem Ⅱ reaction center D1/D2/Cyt b559 complex not only came from the primary donor, P680, but also from other pigments such as from accessory Chl a or Pheo a.     

Elite swimmers and the D allele of the ACE I/D polymorphism

A polymorphism of the human angiotensin-1-converting enzyme (ACE) gene has been identified in which the presence (insertion, I allele) of a 287-bp fragment rather than the absence (deletion, D allele) is associated with lower ACE activity. Several recent studies have shown an association of the I allele with endurance performance, it being found with excess frequency in elite distance runners, rowers and mountaineers. Other workers using heterogeneous cohorts of athletes from mixed sporting disciplines have found no such association. An increasing linear trend of I allele frequency with the distance run amongst Olympic runners and an excess of the D allele amongst sprinters led us to examine whether the ratio of I and D alleles in swimmers competing over different distances would also vary. Swimmers (n=120) from the European and Commonwealth championships and an American college team had their ACE genotype determined and their gene and allele frequencies compared with several control groups, the most closely age-matched of which were 1,248 military recruits. Of the 103 Caucasians, there was a significant excess of the D allele compared with this control group only in the truly elite swimmers of the European and Commonwealth championships (P=0.004). This association remained in those competing over shorter distances (P=0.005 for 400 m and below) but not in the longer events. These findings were confirmed in three further large control groups. A population association study testing whether a genetic marker (the ACE I/D polymorphism) occurs more frequently in cases (elite athletes) than in controls therefore requires a homogeneous cohort of subjects from the same sporting discipline.     

光系统Ⅱ反应中心D1/D2/Cytb559复合物中去镁叶绿素a的光照破坏

高等植物在强光照射下,光合作用受到抑制。光抑制的分子机理已成为目前光合作用研究中最活跃的研究领域之一［１］。由于叶绿体内色素和蛋白分子很多,其中包含有许多与光破坏不直接相关的组分,因此很难确定具体哪个分子受到破坏。用只含少数色素和多肽分子的光系统Ⅱ（ＰＳⅡ）反应中心Ｄ１／Ｄ２／Ｃｙｔｂ５５９复合物［２］可以解决这个问题,现已证明用光照射该复合物能引起原初电子供体Ｐ６８０的破坏［３,４］,并且是一个多步反应［５］,同时还发现有组氨酸残基的光照破坏［６,７］,当存在电子受体的情况下反应中心内部β－ｃ…     

结肠癌中NGX6抑制EGFR/K-ras/JNK/c-Jun/cyclin D1信号通路的研究

候选抑瘤基因NGX6具有抑制结肠癌增殖和转移的作用,研究表明其为表皮生长因子受体(epidermal growth factor receptor, EGFR)的负性调控因子,并可下调JNK通路中重要分子MADD (MAP-kinase activating death domain)的表达,其抑瘤机制是否与抑制EGFR介导的JNK信号通路的活性有关?在已建立的转染NGX6的细胞模型基础上,借助蛋白质印迹(Western blot)和免疫组化方法在细胞和组织水平检测NGX6转染前后EGFR/K-ras/JNK/c-Jun/cyclin D1信号通路中重要蛋白质的表达.结果表明,NGX6转染后结肠癌细胞HT-29在裸鼠体内成瘤明显受抑,差异有统计学意义.Western blot结果显示,在结肠癌细胞中NGX6可明显下调EGFR、K-ras、p-JNK、c-Jun和cyclin D1的表达;进一步采用Western blot和免疫组化法验证NGX6在体内对上述关键分子表达的影响,发现NGX6可抑制裸鼠移植瘤组织中EGFR、K-ras、p-JNK、c-Jun和cyclin D1的表达,与体外结果一致.上述研究表明,NGX6在结肠癌中主要通过抑制EGFR介导的JNK通路的活性而发挥其抑瘤作用,该研究为深入探讨NGX6的机制提供了重要的实验依据.     

Light-Induced Damage of Pheophytin a Molecule in the Isolated Photosystem Ⅱ Reaction Center D1/D2/Cyt b559 Complex

Photodamage of some pigments in the isolated photosystem Ⅱ (PS Ⅱ ) reaction center D1/D2/Cyt b559 complex from spinach has been investigated by means of high performance liquid chromatography. The light-induced damage of pheophytin a (pheo a) in the complex was observed for the first time. The content of pheo a decreased about 47 % by illumination, suggesting only one of the two pheo a molecules in the PS Ⅱ reaction center complex was damaged. No damage of β-carotene was found.     

ACE I/D polymorphism in Alzheimer’s disease

Angiotensin-converting enzyme (ACE) has been reported to show altered activity in patients with neurological diseases. The recent studies found that a 287 bp insertion/deletion (I/D) polymorphism of the ACE gene may be associated with susceptibility to Alzheimer’s disease (AD) but the results have been heterogenous between studies in Europe. In the present study we examined for the first time the association of ACE I/D polymorphism along with APOE genotype in 70 sporadic AD and 126 control subjects in Slovak Caucasians (Central Europe). An increased risk for AD was observed in subjects with at least one APOE*E4 allele (OR=3.99, 95% CI=1.97–8.08). No significant differences for the genotype distribution or the allele frequency were revealed comparing controls and patients for ACE gene. Gene-gene interaction analysis showed increase of the risk to develop AD in subjects carrying both the ACE DD genotype and the APOE*E4 allele (OR=10.32, 95% C.I. 2.67–39.81).     

G6PD通过细胞周期蛋白D1/D2调控人黑色素瘤细胞周期的进程

葡萄糖-6-磷酸脱氢酶(G6PD)在人皮肤黑色素瘤A375细胞中处于高表达与高活性状态, 但G6PD在黑色素瘤发生发展过程中的作用及其具体机制尚不明确.本文在前期运用 siRNA方法构建G6PD敲减的黑色素瘤A375稳转细胞(A375-G6PDΔ)基础上,构建表达载体pBabe-puro-G6PDWT在A375-G6PDΔ细胞中过表达野生型的G6PD基因,从而构建G6PD表达恢复的稳转细胞(A375-G6PDΔ-G6PDWT).3株细胞A375-WT、A375-G6PDΔ和 A375-G6PDΔ-G6PDWT经G6PD酶活性测定、MTT测定、克隆形成实验、流式细胞仪分析细胞周期和Western 印迹检测.结果显示,A375-G6PDΔ-G6PDWT细胞的G6PD蛋白表达量 (0.847 ± 0.080)及其活性(0.394 ± 0.029)分别是A375-G6PDΔ的3.28倍(P＜0.01) 和7.34倍(P＜0.01),分别是A375-WT细胞的91-57%和2.12倍(P＜0.05).与A375-WT细 胞相比,A375-G6PDΔ细胞G0/G1期细胞数增加,S期细胞数减少,增殖指数PI降低了25-70%（P＜0.05）,细胞周期蛋白D1/D2、细胞周期蛋白E表达分别下降37.4%、54.3% (P＜0.01)和17.3%;而A375-G6PDΔ-G6PDWT细胞呈现G1/S期阻滞解除,细胞周期蛋白D1/D2蛋白分别恢复到A375-WT细胞的89.5%和87.6%,细胞周期蛋白E表达未见 恢复,呈现生长增殖和克隆形成率的恢复并接近于A375-WT细胞. 结果提示,G6PD通 过细胞周期蛋白D1/D2调控人皮肤黑色素瘤A375细胞G1期向S期转换的进程,这为黑色 素瘤发病机制的研究提供了新的思路.     

Influence of increasing D/A ratio on geometric and electronic properties of D–A-type copolymers

A series of D–A-type copolymers was designed and studied systematically for the purpose of gaining a deeper understanding of how the D/A ratio may influence the geometric and electronic properties when it varies from 2:1 to 6:1 by using DFT method. The results show that it has a significant effect on the bond length alternation, band gap, bandwidth and effective mass of carriers of the designed D–A-type copolymers. But its influence on the geometric and electronic properties shows something very different in degree when it increases from 2:1 to 4:1 and then increases further from 4:1 to 6:1. It is found that the effects of increasing D/A ratio on geometric and electronic properties are much stronger when the D/A ratio increases from 2:1 to 4:1 than when it further increases from 4:1 to 6:1. The theoretical results show that the polymers with a D/A ratio of 2:1 have much smaller effective mass of carriers and much wider bandwidth compared to those polymers with the D/A ratio of 4:1 and 6:1. Therefore, the designed D–A-type copolymers with a D/A ratio of 2:1 may actually be the better candidates for intrinsic conduction materials.     

光系统Ⅱ反应中心CP47/D1/D2/Cyt b-559复合物中色素分子空间取向的线二色光谱研究

线二色光谱(LD)是研究色素分子在光合膜上空间取向和排布的重要手段.采用低温(100K)吸收光谱和线二色光谱技术研究光系统Ⅱ核心复合物CP47/D1/D2/Cyt b-559中色素分子的空间取向.结果表明,在光系统Ⅱ核心复合物CP47/D1/D2/Cyt b-559中680 nm处有吸收的叶绿素分子Qy跃迁与光合膜平面平行.β-胡萝卜素分子有两种不同的空间取向,其中在470和505nm处有吸收的β-胡萝卜素分子(Ⅰ)与光合膜平面近似平行,而在460和490nm处有吸收的β-胡萝卜素分子(Ⅱ)与光合膜垂直.光破坏实验显示垂直取向的β-胡萝卜素分子对强光敏感.680nm处吸收的叶绿素分子成分复杂,可能包含有P680和核心天线CP47蛋白上的色素分子.     

Orientation of Pigments in the Isolated Photosystem ￠ò Sub-core Reaction Center CP47/D1/D2/Cyt b-559 Complexes: A Linear Dichrosism Study

Linear dichroism (LD) spectroscopy is an important technique in the study of the orientation and organization of pigments in the photosynthetic membrane complexes in vivo and in vitro. In this work, the orientation of the pigments in the isolated photosystem Ⅱ (PSⅡ) sub-core reaction center complexes was analyzed and characterized by means of low temperature absorption and LD spectroscopy. The preparations containing different amounts of CP47 isolated from spinach (Spinacia oleracea L.) chloroplast were used in order to investigate the orientation of pigments in the PSⅡ sub-core CP47/D1/D2/Cyt b-559 (CP47/D1/D2) complexes. Chlorophyll a (Chl a) absorbing at 680 nm in CP47/D1/D2/Cyt b-559 complex showed an orientation of the Q y transition parallel to the membrane plane. It is proposed that there are two forms of β-carotene (β-Car) in CP47/D1/D2/Cyt b-559 complex, denoted as β-Car (Ⅰ)and β-Car (Ⅱ), with different orientations, β-Car (Ⅰ) at 470 and 505 nm is roughly parallel to the membrane plane, and β-Car (Ⅱ) at 460 and 490 nm seems to be perpendicular orientation. Upon the photoinhibitory experiment β-Car (Ⅱ) was found to be photosensitive and easily photodamaged. It also showed that the positive LD signal observed at 680 nm was quite complicated. This signal is tentatively attributed to P680 and some Chl　a of antenna in CP47 protein based upon our measurements.     

假丝酵母属疑难菌株大亚基rDNA D1/D2区域序列分析及其分类学意义*

对根据常规形态和生理生化性状难以确定分类学地位的8株假丝酵母菌,进行了以大亚基(26S) rDNA中D1/D2区域(约500~600 bp)的碱基序列分析为依据的分子分类学研究。根据系统树上所显示的供试菌株与假丝酵母属及相关子囊菌酵母已知种的亲缘关系,以及与最近缘种模式菌株D1/D2区域序列的相似性比较,确定了各个菌株的归属。本研究也显示了DNA序列分析在假丝酵母菌快速鉴定中的优越性。     

日立20PR/52D高速离心机故障排除有方

近两年来中科院上海植物生理研究所先后购置日立20PR/52D高速冷冻离心机12台,在使用过程中,接连发生各种故障,部分机器经常温度控制失灵,在临界温度时压缩机频繁启、停而无法使用,严重影响科研工作进行。日方技术人员检查后认为系电动机整流子烧坏所致,经修理后故障仍未能根本排除。因而提     

HnRNP A/B蛋白D亚群的生物学功能

核不均一核糖核蛋白（heterogeneous nuclear ribonucleoproteins, hnRNPs）是一类结合DNA和RNA的核蛋白,并能在核质间穿梭. A/B型hnRNPs（heterogeneous nuclear ribonucleoproteins,hnRNP A/B）是hnRNPs中研究最为清楚的一大类别,生物信息学分析hnRNP A/B可以区分成A和D两个亚群,已鉴定的D亚群主要成员包括hnRNP AB, D和DL. hnRNP A/B的D亚群均含有2个保守的RNA结合结构域（RNA binding domain, RBD）和1个Gly富集区（glycine-rich domain, GRD）,成员间的主要区别在于N端和C端的长度和序列不同. D亚群与pre-mRNA和其它蛋白质结合成微粒系统,参与pre-mRNA的加工、稳定、核输出以及翻译过程. 此外,D亚群也能结合单链和双链DNA,参与转录起始和端粒的稳定. 因此,hnRNP A/B的 D亚群在各个阶段影响基因的表达,在神经系统发育、肿瘤的发生发展及衰老过程中发挥着多样性的功能.     

S/D处理人纤维蛋白原的病毒灭活验证

在人纤维蛋白原制备工艺中增加Ｓ／Ｄ处理灭活病毒步骤,ＴＮＢＰ和Ｔｗｅｅｎ８０终浓度分别为０．３％和１％,在２５℃处理６小时能有效灭活指示病毒ＶＳＶ（〉３．７５Ｌｏｇ）、Ｓｉｎｄｂｉｓ（〉４．４６Ｌｏｇ）、ＨＩＶ（〉３．６７Ｌｏｇ）,盲传三代未检出病毒     

Staphylococcus aureusα-Toxin: Characterization of Protein/Lipid Interactions, 2D Crystallization on Lipid Monolayers, and 3D Structure

Staphylococcus aureusα-toxin was characterized with respect to surface activity and its interaction with lipid monolayers. The protein alone had a detergent-like behavior at the air/water interface. Its affinity was higher for negatively charged than for neutral phospholipids. The interaction was pH dependent, showing a maximum increase at pH 7.0. Only a small part of the protein oligomer appeared to be inserted into the monolayers. Crystalline sheets of α-toxin were formed using negatively charged phospholipids. Electron microscopy of such areas, at different tilt angles, allowed reconstruction of a three-dimensional model following image processing. The sheets analyzed consisted of two protein layers arranged on a tetragonal lattice. Under the conditions used to grow the crystals the toxin formed 90-Å-wide cylinders with a height of 70 Å. One of the imposed fourfold axes running perpendicular to the plane of the crystalline layer is positioned at a protein-deficient region which forms a 25-Å-wide pore through the oligomer.