短芽孢杆菌低温弹性蛋白酶酶学特性分析

旨在从短芽孢杆菌(Bacillus brevis)XZE116发酵液中分离纯化低温弹性蛋白酶,并对酶学性质进行研究。利用硫酸铵分级盐析、DEAE-Sepharose阴离子交换层析和Sephadex G-75分子筛凝胶过滤层析等方法进行纯化。结果显示,分离纯化到了均一的酶蛋白,酶纯度提高了37.21倍,回收率为35.3%。SDS-PAGE及Sephadex G-75分子筛凝胶过滤层析显示酶蛋白为单亚基蛋白,分子量是32.6 kD。最适作用温度25℃。在pH7.5-10.5范围内酶活性及稳定性较高,最适作用pH9.0,Mg2+对酶有明显激活作用。丝氨酸蛋白酶特异性抑制剂强烈抑制酶活性,表明所纯化到的弹性蛋白酶属于丝氨酸蛋白酶。酶对阴离子表面活性剂(0.1%SDS)、阳离子表面活性剂(0.1%CTAB)和非离子型表面活性剂(1%Tween80)均具有很强的稳定性。鉴于短芽孢杆菌XZE116弹性蛋白酶具有以上优良酶特性,它在肉品嫩化领域具有潜在的应用价值。     

番茄感染TMV诱导的β-1,3-葡聚糖酶的纯化和性质

番茄系统感染TMV诱导对胞外β—1,3—葡聚糖酶活性升高。番茄叶胞外提取液经冰冻干燥浓缩、-20℃丙酮沉淀、CM-Sephadex C-25离子交换层析和PBE 94聚焦层析纯化,获得PAGE和SDS-PAGE均一的β—1,3—葡聚糖酶。测得该酶的分子量为22kD;以昆布多糖为底物,该酶的最适pH5.4,最适温度30～40℃;K_m和V_(max)值分别为5.64mg/ml和 0.328nmol/s。在感染TMV的番茄叶中,β—1,3—葡聚糖酶活力大部分位于胞外,它是番茄叶胞外提取液中主要的病原相关蛋白。     

固氮鱼腥藻的蛋白水解酶及其部分性质的研究

应用溶菌酶处理,超声破碎细胞,通过差异离心和解离剂处理,将细胞的不同部分分开。以水解α-酪蛋白反应检测蛋白水解酶活性,结果表明,在细胞的可溶部分、内细胞质膜、外膜及胞浆周围区均存在蛋白水解酶活性。异形胞可溶部分的蛋白酶活比营养细胞可溶的蛋白酶活高4—5倍。在固氮条件下,营养细胞可溶性蛋白酶反应最适温度为50—55℃,65℃时,酶活迅速下降。有Ca^2 5mmol／l时,蛋白酶在60℃稳定,无Ca^2 存在下,酶液在60℃预处理10分钟,酶活性丧失80％以上。酶反应的最适pH为8—10。而且氮饥饿之后,培养基的pH值对细胞蛋白酶活水平有明显影响,氮饥饿24小时内,蛋白酶活迅速增加,但在碱性条件下,酶活水平比在中性条件下要高得多。邻菲哕啉对蛋白酶活性有严重的抑制,EDTA仅有轻微抑制,而PMSF对细胞蛋白酶活的抑制作用,与细胞氮饥饿时间有关。     

短小芽孢杆菌2080碱性蛋白酶的纯化与性质

短小芽孢杆菌（Bacillus pumilus）2080碱性蛋白酶的发酵液经超滤、硫酸铵沉淀、CM Sepharose Fast Flow和DEAE Sepharose Fast Flow离子交换层析得到了纯化的组分。SDS-PAGE电泳分析显示其分子量约为61kDa。酶学性质研究表明,该纯化酶的最适pH为10．5,最适温度为50℃。     

嗜热芽孢杆菌XJT—9503高温中性蛋白酶的研究 Ⅱ.酶的提纯及酶学特性研究

嗜热芽孢杆菌XJT—9503菌的发酵液经硫酸铵和丙酮分级沉淀分离纯化得到聚丙烯酰胺凝胶电泳均一的高温中性蛋白酶制品。SDS—PAGE测得酶分子量为3000。当以酪蛋白为底物时,酶反应最适温度为65℃,最适pH为7．在PH6．5—9范围内稳定。在65℃、0、02MpH7．5的磷酸缓冲液中的半衰期为54min。金属离子铜、汞、铝强烈抑制酶活,钙离子,镁离子对酶活有促进作用。     

M-26碱性木聚糖酶的分离纯化及酶学性质研究

从Bacillus pumilus M-26发酵液中分离纯化碱性木聚糖酶,进行酶学性质研究,同时制备工业用碱性木聚糖酶制剂。首先将M-26发酵液进行硫酸铵盐析,制备工业用碱性木聚糖酶干品;然后进行sephadexG-25层析脱盐和cellulose DE-52层析得以纯化。硫酸铵的饱和度50%,酶制剂的酶活可达9 000 IU/g,收率为85%;分离纯化使酶的比活为126.32 IU/mg蛋白,纯化倍数为19.89,酶的回收率12.83%;分子量约为20 ku;M-26碱性木聚糖酶的最适温度和pH分别是55℃和pH 8.0,具有一定的耐碱性;该酶无纤维素酶活性,Fe2＋对其有激活作用;Mn2＋、Zn2＋、Fe3＋、Cu2＋对其具有抑制作用。短小芽胞杆菌M-26碱性木聚糖酶具有纸浆生物漂白应用前景。     

乳酸菌Enterococcuse faecalis TN-9低温蛋白酶的提纯及性质

对产自乳酸菌Enterococcuze fecalis TN-9的蛋白酶,进行了硫酸铵沉淀,DEAE—Sephadex A-25以及DEAE Cellulofine A-500离子交换层析的3步纯化和特性研究。纯化酶Native PAGE显示1条蛋白带。SDSPAGE和凝胶层析分子量分别为30ku及69ku。纯化酶最适作用温度为30℃,最适作用PH为7．5～8．0,在pH6．0～9．5和45℃以下条件下稳定,在0℃下显示了6．1％的相对活性,60℃以上热处理完全失去酶活。该酶被EDTA-2Na,Hg^2＋、Cu^2＋、Ni^2＋、Ag^2＋、Co^2＋及Pepstatin A不完全抑制。Zn^2＋对蛋白酶具有明显的激活作用。纯化酶作用于偶氮酪蛋白的Km和Vmax分别为0．098％和72mg／（h·mg）。该酶为N末端VGSEVTLKNS的明胶酶（Gelatinase）的一种,性质属于低温蛋白酶。     

十二节杆菌胞外脂肪酶的纯化和性质研究

十二节杆菌发酵得到的胞外脂肪酶,在5L发酵罐经过34h培养,最高酶活可达75 U/mL。通过硫酸铵梯度沉淀和疏水层析纯化,脂肪酶纯化26倍,总得率24.3%。SDS-PAGE显示脂肪酶分子量为33 kD,脂肪酶在40℃和pH 7.0时酶活力最高,同时在24℃经过48h仍保持一半左右的活力。该脂肪酶的酶活受K ,Mg2 激活,而受Zn2 与Co2 的抑制。     

红树林微生物DH-2胞外蛋白酶的性质及产酶条件优化

从大亚湾红树林土壤样品中分离得到产蛋白酶菌株,鉴定所产胞外蛋白酶的酶学性质以及菌株的最佳发酵培养条件。采用平板透明圈法筛选菌株,福林酚显色法测定蛋白酶的酶活,通过单因素和正交试验确定其最佳发酵培养基以及发酵条件。从壤样品中分离得到一株产蛋白酶的枯草芽孢杆菌DH-2,该菌株分泌的蛋白酶最适反应pH和温度分别为8.0和65℃,50℃保温处理60 min后,剩余酶活仍保留80%以上。该蛋白酶对多种金属离子、有机溶剂及表面活性剂均有较好的耐受性。确定该菌株产蛋白酶的最适条件:1%(m/V,下同)可溶性淀粉,1%胰蛋白胨、1%NaCl,初始pH 5.5及7%的接种量,40℃培养36 h。在最适条件下测得其发酵液的酶活为236.30 U/mL,约为初筛时的酶活的8倍。该蛋白酶具有较为广阔的作用温度和pH范围,金属离子、有机溶剂及表面活性剂耐受性好,酶的性质比较稳定。     

家蚕肠道枯草杆菌产蛋白酶的发酵条件与酶学性质

肠道微生物分泌的蛋白酶可促进家蚕对桑叶养分的消化吸收,枯草芽孢杆菌是家蚕肠道内一种重要的产蛋白酶菌株。为提高枯草芽孢杆菌蛋白酶的高效利用,对该菌株适宜发酵条件及酶学性质进行了研究。结果表明：各因素对枯草芽孢杆菌产酶活性影响的大小顺序依次为：pH值〉培养温度〉培养时间〉装液量;最适的产酶条件为：pH=7,培养温度：30 ℃,培养时间：36 h;对枯草芽孢杆菌产蛋白酶进行初步提纯后并研究得出该酶反应的最适pH 10.0,最适反应温度为：60 ℃;该酶为碱性蛋白酶、不耐高温、不耐酸,但在35 ℃条件下热稳定性较好。     

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.     

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.     

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。     

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.     

真菌类遗传学分析的知识结构教学

本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。 Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching.     

（鱼句）亚科花（鱼骨）型鱼类骨骼系统的比较

对我国花型Hemibarbuspattern鱼类作了骨骼系统比较,结果表明,此类型鱼类脑颅较长,副蝶骨平直或稍弯曲,眶蝶骨腹纵嵴发达(铜鱼Coreius septentrionalis例外),下颞窝和咽突中等大,基枕骨后突发达;脑颅中的上筛骨的后突、侧筛骨的外筛突,蝶耳骨的外突、上耳骨的后突、围眶骨和后颞窝等均有明显的差异;咽颅中的舌颌骨、尾舌骨、鳃盖骨和下咽齿的列数等又有显著的区别;附肢骨骼中的腰带骨、脊椎骨中的复合神经骨和第4椎骨腹侧的悬器等也有不同之处。据此,这些差异和区别可作为属间或种间的分类依据。