豌豆叶绿体偶联因子腺三磷酶的分离与纯化

豌豆叶绿体经焦磷酸钠盐溶液洗涤,并以加蔗糖的Tris—Tricine缓冲液作分离介质,其抽提液通过 DEAE—Sephadex A_59柱层析,可得较高纯度的腺三磷酶制剂。经免疫沉淀反应、需镁腺三磷酶活和 SDS—聚丙烯酸胺凝胶电泳证明,这种豌豆叶绿体偶联因子腺三磷酶具有五种蛋白带,与菠菜叶绿体偶联因子腺三磷酶的五种亚单位(α,β,γ,δ和ε亚单位)具有相近的分子量,但两者的α和β亚单位大小有异。     

玉米叶绿体atpB基因表达产物的特性及其抗体对CF_1功能的影响

利用大肠杆菌获得玉米叶绿体ａｔｐＢ融合基因及非融合基因的高效表达。从大肠杆菌中部分分离纯化得到的这些ａｔｐＢ基因表达产物都表现出微弱的水解ＡＴＰ的活力。由其中一种融合蛋白β_１制备得到的抗血清对菠菜叶绿休偶联因子的光合磷酸化功能影响不明显,对游离ＣＦ_１的Ｃａ~（２＋）－ＡＴＰ酶活力也无明显影响,但却能明显地促进它的Ｍｇ~（２＋－）ＡＴＰ酶活力。     

利用CHAPS分离豌豆叶绿体偶联因子复合物

近年来不少工作者对叶绿体偶联因子复合物的结构、功能和发生的问题颇为关注(程秋琛等 1986,Merchant等 1985,Nelson 1982,Pick等1979,Strontman等1983,Suss等 1983)。分离生物膜蛋白质的     

小麦原生质体和叶绿体分离及其光合速率的测定

具有光合能力的叶绿体,必须具有完整的被膜,分离这种叶绿体多采用短时间高速冷冻离心的方法。但此法仅适用于菠菜和豌豆等植物。在小麦上至今未见成功的报道。     

叶片预照光对光合磷酸化和电子传递偶联效率的促进作用

菠菜叶片经预照光处理后提取的叶绿体,不但光合磷酸化活力增加,而且偶联效率P/O也提高,其提高P/O的作用与多粘菌素的作用不能叠加,叶片预照光可能通过使偶联因子产生漏能减少的变构而提高p/O的。用两阶段光合磷酸化法测得叶片预照光,在促进光合磷酸化时也能促进高能态积累。用CF_1抗体,NEM和五羟黄酮等处理叶绿体的研究表明,叶片预照光引起CF_1的构象变化——γ,亚单位上的SH基内埋而α.β亚单位上的催化中心却更加暴露。活体中的P/O值也许会比一般离体的高。     

水分胁迫对甘薯叶肉细胞光合电子传递的影响

水分胁迫降低了甘薯叶肉细胞的光合能力。在有解偶联剂存在时,水分胁迫对叶肉细胞的光合电子传递没有影响,但在无解偶联剂存在下,水分胁迫促进了甘薯叶肉细胞的光合电子传递,表现出明显的解偶联效应。水分胁迫伤害了甘薯叶绿体偶联因子结构,使ATP合成受阻,叶肉细胞的光合滞后期加长。     

水分胁迫对甘薯叶肉细胞光合电子传递的影响

水分胁迫降低了甘薯叶肉细胞的光合能力。在有解偶联剂存在时,水分胁迫对叶肉细胞的光合电子传递没有影响,但在无解偶联剂存在下,水分胁迫促进了甘薯叶肉细胞的光合电子传递,表现出明显的解偶联效应。水分胁迫伤害了甘薯叶绿体偶联因子结构,使ＡＴＰ合成受阻,叶肉细胞的光合滞后期加长。     

叶绿体蛋白质组研究进展

亚细胞蛋白质组学是近年来蛋白组学研究中的一个热点。通过细胞器的纯化和亚细胞组分的分离,降低了样品的复杂性,增大了相应蛋白质组分的富集,有利于由此分离获得的蛋白质的序列分析及功能鉴定。叶绿体蛋白质组为植物亚细胞蛋白质组学研究中相对全面的一部分,利用亚细胞分离结合双向电泳技术系统地鉴定叶绿体中蛋白质组分是获取叶绿体蛋白质信息、确定其功能的重要技术手段。本文就近年来植物叶绿体蛋白质组涵盖的叶绿体内、外被膜、叶绿体基质、类囊体膜和类囊体腔蛋白的研究进行综述,以全面认识叶绿体蛋白的组成、特点及其在叶绿体生理生化代谢网络中的作用。     

日光温室光温因子对黄瓜叶绿体超微结构及其功能的影响

在日光温室内,研究了光温因子对黄瓜叶绿体超微结构及其功能的影响．结果表明,因季节之间光、温条件不同,日光温室黄瓜叶片显微结构和叶绿体超微结构有一定差异,1月份光照弱叶肉细胞较大,而5月份光照强叶绿体数较多．在该试验条件下,未发现叶片光合速率与叶绿体超微结构之间有直接或密切的相关性．在各生长季节其光合速率均为第4叶>初展叶>基部叶,与叶龄及各叶位的受光量有关．如果将不同叶位叶放在相同的光照下,则差异明显减少．黄瓜叶片的叶肉细胞、叶绿体和淀粉粒的大小以及叶绿体数、基粒数、基粒厚度、基粒片层数都随叶位的下降而呈增加趋势。不同品种、同品种不同生长时期的叶片显微结构和叶绿体超微结构及其功能也有一定的差异．限制日光温室冬季黄瓜光合作用的主要因素是光照弱、有效光照时数少,而在晴天温度的限制作用相对较小。阴天因光照弱而导致的室内低温则是限制黄瓜生长的关键因素．     

多粘菌素B对光合磷酸化的促进作用

多粘菌素B在低浓度的磷酸盐存在下,抑制光合磷酸化和电子传递,但在较高浓度的磷酸盐存在下,却能促进光合磷酸化和提高P/O值。多粘菌素B在促进光合磷酸化时与无机磷酸之间存在着类似竞争的关系,并显示出能增加叶绿体的毫秒延迟发光和用中性红表示的类囊体膜内外的pH变化,多粘菌素B亦能促进光下的ATP_P_j交换。根据上述实验结果;我们推测多粘菌素B在类囊体膜上可能有两个作用部位,一个在类囊体膜上,另一个在偶联因子(CF_1)的β亚单位上。     

不同浓度亳菊水提物对秀丽隐杆线虫脂滴凝聚影响观察

目的探讨毫菊对秀丽隐杆线虫脂肪沉积的影响。方法用不同浓度毫菊水提取液配制NGM培养基,培养同步化秀丽隐杆线虫,成虫经油红0染色,异丙醇萃取,测定OD值,并与普通NGM培养基培养的同步化线虫相比较。结果随着浓度的提高,线虫体内的脂肪沉积量呈现出一定的曲线变化,其具体机制有待于进一步研究。     

重组人钙调素的制备及其对细胞增殖作用影响的研究

用PCR方法获得人钙调素基因Ⅲ(hCaMⅢcDNA),将其插入表达载体pBV220,构建重组表达质粒hCaMⅢ/pBV220,阳性重组子在大肠杆菌DH5α中经温度诱导可高效表达CaM蛋白,经15%SDS-PAGE分析,可观察到一分子量与理论值相符(约17kD)的诱导表达条带.进一步分析表达产物的性质表明,CaM主要以可溶性形式表达.Westernblot结果证实,17kD的表达条带可与标准鼠抗CaMMcAb起特异反应.用Phenyl-SepharoseCL-4B疏水亲和层析法纯化重组菌超声上清表达产物,可获得纯度达95%以上的CaM,每1L菌液可获CaM纯品3～4mg.生物活性测定结果提示,rhCaM具有与标准人脑CaM(Sigma)同样的激活NAD激酶的活性.将K562细胞及SP2/0细胞分别接种于24孔或96孔培养板,加入不同浓度rhCaM、CaM拮抗剂三氟拉嗪(TFP),培养48h后,用MTI比色法检测细胞增殖状况.rhCaM在一定浓度范围内与细胞增殖率成显著正相关;CaM拮抗剂TFP可抑制细胞增殖.将rhCaM加入已受TFP抑制的细胞,可恢复正常的细胞增殖功能.     

大肠杆菌O157菌体抗原基因检测芯片的制备

选择编码O157菌体抗原特异合成酶的rfbE基因设计引物于口探针,并制备检测芯片,通过两次PCR扩增,制备荧光标记的靶序列,并与芯片进行杂交,检测O157菌株和非O157病原体。结果所有O157菌株均在芯片相应探针处出现阳性信号,非O157杂交结果均为阴性;芯片检测灵敏度比PCR检测高50倍。说明基因芯片可以快速、灵敏、特异地检测O157菌体抗原,为建立快速灵敏的检测细菌病原体特征和鉴别诊断的自动分析系统提供了新方法。     

蟛蜞菊的生化他感作用及生化他感作用物的分离鉴定

蟛蜞菊是华南常见的园林绿化草本植物。植被调查表明其群落中杂草很少,形成蟛蜞菊纯群落。用琼脂培养基培养蟛蜞菊发现其分泌物对萝卜和黄瓜的萌发和幼草生长有生化他感作用。蟛蜞菊的组织抽提物对萝卜、稗草、马唐、窝苣和苜蓿５种植物幼苗生长都有抑制作用。用蟛蜞菊作覆盖物对马唐、大画眉草和空心莲子草幼苗生长有抑制作用。用真空液相色谱、快速柱色谱等赍蟛蜞菊地上部分离出２个纯化合物和１个较纯组分。纯化合物用质谱、红外     

Disruption of the gene (spo0A) encoding sporulation transcription factor blocks endospore formation and enterotoxin production in enterotoxigenic Clostridium perfringens type A

This study identified a functional spo0A ORF in enterotoxigenic Clostridium perfringens type A. To evaluate the function of spo0A, an isogenic spo0A knock-out mutant was constructed. The spo0A mutant was unable to form endospores and produce enterotoxin, however, these defects could be restored by complementing the mutant with a recombinant plasmid carrying the wild-type spo0A gene. These results provide evidence that spo0A expression is essential for sporulation and enterotoxin production in C. perfringens.     

A 31p and 15N NMR study of the extraction of uranyl nitrate by Di-2-ethylhexyl phosphoric acid

Low temperature ³¹P and ¹⁵N NMR spectroscopy was used to investigate the species forming in the organic layer following the extraction of uranium from nitric acid solutions with di-2-ethylhexyl phosphoric acid. It was found that uranium is extracted from neutral solutions as the 1:2 complex UO₂A₂ regardless of what anion is present. For dilute nitric acid solutions, the uranium is extracted both as associated and mixed nitrato species. As the nitric acid concentration of the aqueous layer increases, the mixed nitrato complex, UO2(NO₃)A·HA, becomes predominant.     

Crystal structure of (L-Arg)-BO bovine insulin at 0.21 nm resolution

The crystal structure of (L-Arg)-B0 bovine insulin has been determined, using data to 0.21 nm and atomic parameters of 2Zn porcine insulin as a starting model, by the difference Fourier method, the restrained least square method and X-PLOR package, interspersed with careful review of the electron density, to a final R-factor of 0.182 and r.m.s. deviation of 0.002 2nm for the bond lengths and 4.3° for the bond angles. The electron densities of additional (L-Arg)-B0 residues to B-chain N-terminus of two monomers in each asymmetric unit are very dear. The crystallographic micro-environment of the N-terminus of the B-chain is different from that of rhombohedral 2-zinc insulin.     

Head anatomy of adult Sisyra terminalis (Insecta: Neuroptera: Sisyridae) – Functional adaptations and phylogenetic implications

The external and internal head anatomy of Sisyra terminalis is described in detail and compared with data from literature. A salivary pump consisting of a peculiar reservoir and a hitherto unknown muscle, M. ductus salivarii, is newly described for Neuroptera. The upward folded paraglossae form a secondary prolongation of the salivary system. These structures are discussed as functional adaptations for feeding on aphids and desiccated honeydew. In a phylogenetic analysis the basal position of the Sisyridae within Neuroptera is retrieved. The following new synapomorphies are postulated: (1) for Neuropterida, the presence of a M. submentomentalis and prepharyngeal ventral transverse muscles, and the absence of a M. submentopraementalis; (2) for Neuroptera and Sialidae, the presence of a mandibular gland; (3) for Neuroptera, the presence of four scapopedicellar muscles; (4) for Neuroptera exclusive Nevrorthidae and Sisyridae, the weakening of dorsal tentorial arms, the presence of a M. tentoriomandibularis medialis superior and the shifted origin of M. tentoriocardinalis.     

Purification and Characterization of B2 Bradykinin Receptor from Rat Uterus

Abstract: A B₂ bradykinin (BK) receptor was solubilised and partially purified from rat uterine membranes by a combination of ammonium sulphate precipitation, desalting on Sephadex G-50, and hydroxyapatite and wheat germ agglutinin affinity chromatography. The partially purified BK receptor, enriched 1,500-fold, was then cross-linked to ¹²⁵l-Tyr⁰-BK using disuccinimidyl suberate and purified to homogeneity as a single protein species on two-dimensional gel electrophoresis with a molecular mass of 81 kDa. This molecular size was in agreement with the value of 80–120 kDa estimated from Sephacryl 300 size exclusion column chromatography of the B₂ receptor. The partially purified and the crude solubilised B₂ BK receptor from rat uterus showed similar affinities for BK and the BK analogues iodo-Tyr⁰-BK, D-Phe⁷-BK, and des-Arg⁹-BK, indicating that the ligand binding specificity of the receptor had been retained during the purification procedures. The biochemical properties of the solubilised B₂ BK receptor correspond to those of a hydrophobic acidic glycoprotein (isoelectric focusing gave a value of 4.5–4.7) that binds specifically to wheat germ agglutinin but has no affinity for either concanavalin A or lentil lectin, suggesting the absence of terminal mannose or glucose residues.