具有NGF活性通过二硫键连接的 2个小分子多肽的制备及鉴定(英文)

神经生长因子 (NGF)作用广泛 ,β NGF是神经生长因子的活性部分 .由于 3对二硫键的影响 ,体外表达NGF很难形成正确折叠的肽链 .由于神经系统血脑屏障的存在 ,大分子肽链的给药途径是一个不可忽视的难题 .根据NGF的氨基酸序列及其晶体构象资料 ,选择CNBr在 9位Met处 ,胰蛋白酶在Arg或Lys处裂解 β NGF .经过SephadexG 5 0层析、DE 5 2纤维素离子交换层析和反相高压液相层析分离纯化后获得NGF活性片段 .氨基酸组成分析及氨基酸序列分析结果表明 ,此片段由 16肽GEFSVCDSVSVWVGDK与 14肽HWNSYCTTTHTFVK通过 1对二硫键连接而成 .8日龄鸡胚背根神经节生物活性分析表明 ,其最佳作用浓度为 0 0 0 1～ 0 1μg L .它的成功分离和鉴定为合成或表达高活性小分子神经营养物质奠定了关键而重要的基础 .     

神经生长因子对成纤维细胞生长的负调节作用

从小鼠颌下腺分离所得的神经生长因子(nervegrowth factor,NGF)是分子量为130000的多肽,其沉降系数为7S,由三种亚基α,β,γ组成,化学式为α_2βγ_2,其中β亚基可以完全表现NGF的生理效应.NGF的生物学效应比较广泛,它对神经系统的发育、分化有重要促进作用,在神经系统损伤后起修复、营养作用.另外,NGF对免疫系统、生殖系统也有一定作用.近年来,NGF与肿瘤关系的研究尤其     

小鼠颌下腺粗提物中神经生长因子活力的测定

神经生长因子(Nerve Growth Factor,简称 NGF)系1951年 Levi-Montalcini 发现。大量的体内外实验证明,它对交感神经细胞和感觉神经细胞有促进成熟与分化的作用。NGF 广泛存在于动物体内,以成年雄性小鼠颌下腺中含量最高,其次是豚鼠前列腺和蛇毒中。它为一蛋白质,分子量130000,通常称为7S NGF,由5个亚基组成,只有β亚基具有促进神经生长的特性。用不同方法提取,可     

神经生长因子:分布、化学及功能

神经生长因子(nerve growth factor,NGF)是目前唯一被阐明并确定化学结构的典型营养物质,其生物学功能已经披露。它是外周感觉和交感神经元分化与生存所必需的一种蛋白质。它的首次发现应追溯到1948年     

神经生长因子在脑损伤后可预防神经元坏死

神经生长因子(NGF)对外周交感和感觉神经节的正常发育和维持起决定性作用,在哺乳类中枢神经系统可能也具有营养作用。据认为,中枢胆碱能神经元在其轴突被切断后所发生的退化、坏死,是由于失去了一种逆向转运的神经营养因子,它可能是 NGF。美国乔治敦大学 L.F.Kromer 博士最近对此进行了实     

肌肉注射人神经生长因子基因逆轴突传递修复神经损伤的研究进展

神经生长因子(NGF)促进中枢及外周神经系统神经元细胞存活、分化、轴突再生等重要作用已得到临床的广泛证实。目前临床上主要以局部或肌肉注射NGF蛋白的方式对神经系统的损伤进行治疗。但NGF半衰期短、局部应用副作用大、费用昂贵、难以透过血脑屏障等缺点而限制临床应用。长期以来,科研工作者致力于寻求一种理想的途径或方法以克服这一缺陷。随着基因工程技术的飞速发展,研究人员发现通过骨骼肌肌肉注射途径,以非病毒载体介导外源的NGF基因体内表达并逆轴突传递到神经损伤部位,有望解决这一难题。本文将就NGF及受体的基本结构和特性、逆轴突传递的机制、非病毒载体结合骨骼肌肌肉注射的基因治疗等方面进行总结和阐述。     

人神经生长因子的原核高效表达

神经生长因子(nerve growth factor,NGF)是神经系统最重要的生物活性分子之一,也是最早发现和最典型的神经营养因子。它影响外周和中枢神经系统某些神经元的存活与分化;NGF在神经损伤时可保护其效应神经元,促进神经纤维再生,增加脑移植中某些神经元的存活;它对外伤、中毒、老化等因素引起的脑疾患有治疗作用,并具有神经修复功能,尤其是对早老性痴呆症、帕金森氏病的治疗作用比较乐观。虽然NGF在神经损伤和神经退行性病变的诊断和治疗中有巨大的临床应用价值,但天然NGF受到雄性小鼠颌下腺这     

神经生长因子促进坐骨神经再生修复的酶组织化学研究

目的研究对兔右坐骨神经损伤后局部给予蛇毒神经生长因子(NGF),观察坐骨神经酶活性变化和超微结构的恢复情况,探讨NGF对神经再生的影响.方法乙酰胆碱酯酶(AChE)、酸性磷酸酶(ACPase)的酶组织化学技术和电镜技术.结果神经损伤后:AChE活性明显下降,NGF组的AChE活性恢复快于盐水对照组;ACPase活性逐渐增高,NGF组的ACPase活性恢复时间短于盐水对照组.坐骨神经的超微结构在神经损伤后也发生变化,NGF组的变化程度小于盐水对照组,恢复时间短于对照组.结论NGF可通过影响酶物质的代谢而起到加快受损神经恢复的作用.为临床上应用蛇毒NGF治疗周围神经损伤提供形态学依据.     

鸡胚背根神经节培养法测定神经生长因子(NGF)活性的条件优化

目的探索一套稳定可靠的鸡胚背根神经节测定NGF活性的实验条件.方法通过观察培养基、鸡血浆和鸡胚浸液的比例、背根神经节部位、培养时间等条件对NGF刺激神经节生长的影响,从而建立一套该培养法检测NGF活性的优化条件.结果以DMEM为母液,在含20%鸡血浆和15%鸡胚浸液的培养基中,利用伊莎褐鸡胚腰椎背根神经节,在终浓度为30 ng/ml的蛇毒NGF的刺激下,培养36h可以得到较好的实验结果.结论该条件简单实用、分辨率高、重复性好.     

C-H_3加强神经生长因子对培养的鸡胚背根神经节细胞的作用

在培养的鸡胚背根神经节上观察了 C-H_3(GhineseH_3)、神经生长因子(NGF)以及 C-H_3和 NGF 的混合剂对神经细胞的影响。主要结果如下:1.C-H_3处理的标本和对照组没有差别。培养3d 的节神经细胞数平均约420个;6d 时,部分细胞衰退,降到200个。2.NGF 能促进节神经纤维外长,增加神经母细胞向神经元的转变。培养3d 的节神经细胞数平均约700个;6d 时720个。NGF 维持神经元的存活,延缓神经元的衰退。3.C-H_3和NGF 的混合剂不仅增进节神经纤维的长出,而且还延缓了长出纤维的消退,消失时程比NGF 组延长一倍。培养3d 的节神经细胞数平均约1000个,是2.4倍于对照,1.4倍于 NGF组;培养6d 时1120个,为对照组的5倍,NGF 组的1.5倍。混合剂的效果比 NGF 更好。结果表明,C-H_3增强 NGF 对培养的节神经细胞存活的效应。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.