眼镜王蛇(Ophiophagus hannah)中L-氨基酸氧化酶(LAO)的纯化及某些理化性质和酶学性质的研究

本文报道了眼镜王蛇毒中LAO的纯化及某些性质,从眼镜王蛇毒中所分离的LAO在比活力、酶学性质及同工酶谱方面与从其他蛇毒来源的LAO存在显著不同. 聚丙烯酰胺凝胶电泳显示该酶是均一的.由梯度聚丙烯酰胺凝胶电泳测得全酶分子量约为1.5×105.SDS梯度聚丙烯酰胺凝胶测得亚基分子量为7.3×104.表明该酶是由二个分子量相同的亚基组成.吸收光谱显示每个分子含二个FAD. 酶氧化L-丙氨酸的最适pH为8.7—9.0.当底物浓度大于3n M时,出现明显产物抑制.该酶具有一定热稳定性,在55℃以下加热40分钟对酶活力基本无影响,当酶的浓度低于5.7微克/毫升时酶的浓度和酶反应速率呈线性关系.     

小鼠腹水癌细胞中一种DNA聚合酶-模板复合体的纯化和特性鉴定

本文通过两次不连续密度梯度离心和琼脂糖凝胶过滤,对小鼠腹水癌细胞中的DNA聚合酶一内源模板复合体进行了纯化,纯化后酶活性提高了500倍,经鉴定其分子大小为510,000道尔顿。电子显微镜下观察呈均匀球状,直径100—110埃。复合体经DEAE纤维素柱层析分离为两种酶蛋白组份和一种DNA模板。其中最主要的酶蛋白分子量为300,000道尔顿,沉降系数为9.5s;内源DNA模板经聚丙烯酰胺凝胶电泳分析呈单一区带,沉降系数为3.8s。     

不同动物毛的两向凝胶电泳鉴定及其角蛋白组成分析

本文报道一种用于鉴定不同种属动物毛的方法。以二硫苏糖醇为还原剂在尿素存在下,抽提出毛纤维中可溶性角蛋白,经羧甲基化修饰后,通过两向聚丙烯酰胺凝胶电泳,结合对电泳区带和特征斑点的扫描,可对动物毛角蛋白组成作定性和半定量分析。     

一种从人体胚胎中分离纯化的限制性核酸内切酶HsaI

从人、Homo sapiens、胚胎组织及细胞核的抽提物中分离纯化了一种核酸内切酶HsaI。它具有Ⅱ类核酸内切酶的功能、从该酶对λDNA的切割位点来看,它是EcoRI的同功酶,但在洗脱特性上不同于EcoRI。经SDS-聚丙烯酰胺凝胶电泳分析可得两条考马氏兰染色带,分子量分别为65000和22000 Daltons。     

蜂王浆超氧化物歧化酶分离纯化及部分性质研究

本文采用硫酸铵盐析、SephedexG-150柱层析从蜂王浆中分离出了超氧化物歧化酶（SOD）。经聚丙烯酰胺凝胶电泳显示单一蛋白区带。此酶比活力为1887 .4U/mg，纯化倍数为524.3，回收率为12.47%，最适pH8.3，最适温度为25℃。Mn^2,Cu^2 ,Ba^2 ,Mg^2 对此酶在有激活作用，Zn^2 则具有抑制作用。过氧化氢和乙醇-氯仿实验表明：蜂王浆中的SOD属Cu/Zn-SOD。     

CMC-g-DNA接枝共聚物的合成与表征

在磷酸盐缓冲溶液中用1-(3-二甲氨基丙基)-3-乙基碳二亚胺(EDC)与N-羟基琥珀酰亚胺(NHS)活化羧甲基纤维素钠(CMC)侧链上的羧基; 在室温下再将活化的CMC与5'端经氨基修饰的单链脱氧核糖核酸(DNA)齐聚物(ODNs)反应, 获得CMC上接枝ODNs的共聚物(CMC-g-ODNs), 以Lambda DNA为模板, 通过聚合酶链式反应(PCR), 将接枝的ODNs扩增为长度为1300个碱基对的双链DNA, 从而制得CMC侧链上接枝DNA的共聚物CMC-g-DNA. 采用傅里叶红外光谱仪测定CMC与NHS形成的中间体; 用水平式琼脂糖凝胶电泳和垂直板变性聚丙烯酰胺凝胶电泳对CMC-g-DNA接枝共聚物进行表征. 结果表明, 合成了CMC-g-DNA接枝共聚物, 且在酸性条件下CMC的活化效果更好; 同时, 接枝在CMC上的DNA在琼脂糖凝胶电泳中迁移速率加快, 而在聚丙烯酰胺凝胶电泳中迁移速率减慢.     

从猪血中分离纯化高纯度的猪血红蛋白

为了从猪血中分离纯化高纯度的猪血红蛋白,建立了通过超滤、DEAE-Sepharose Fast Flow离子交换色谱和Sephadex G-75凝胶 排阻色谱三步法制备高纯度猪血红蛋白的方法,并通过十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)、高效凝胶排阻色谱和反相高 效液相色谱方法,对纯化后的猪血红蛋白进行了鉴定。经三步分离纯化后,猪血红蛋白的纯度大于99%,含量为1.328 g/L。     

pH敏感相分离高分子的免疫分析应用研究

合成了溶解性受pH值影响的高分子化合物聚甲基丙烯酸甲酯-丙烯酸-顺丁烯二酸酐(MAM)及聚甲基丙烯酸一丙烯酰胺-N-羟基琥珀酰亚胺丙烯酸酯(MAN),分别与抗体进行了共价连接,将其用作免疫分析载体,利用其溶解性可调节特征,建立了新的免疫分析方法.以聚甲基丙烯酸-丙烯酰胺-N-羟基琥珀酰亚胺丙烯酸酯为载体,对血清中乙肝表面抗原进行了检测,阴阳性检出结果与常规ELISA方法相符.     

硝酸铈对大鼠体内酯酶酶谱的影响

采用聚丙烯酰胺凝胶电泳技术，研究了含不同浓度的稀土饲料喂养大鼠对大鼠体内9种器官和组织中（心脏，肝脏，肾脏，肌肉，胃，血清，睾丸，胰腺，肺）酯酶酶谱的影响，结果表明：稀土的作用导致酯酶酶谱发生显著的变化，原有的一些谱带消失，出现了一些新的谱带，这种影响随器官和组织的不同而不同，谱带强度的改变也因器官和稀土浓度不同而异。特别是在心，肝，肾，肌，胃中酯酶（EST）同工酶酶谱和稀土的浓度之间具有一定的相关性，对酶活性起着抑制或和激活作用，面对血清，睾丸，胰腺，肺中EST同工酶的影响则相对较小，可见，稀土对大鼠体内酯酶酶谱的影响是广泛而显著的。     

辣根过氧化物酶酶促体系引发丙烯酰胺聚合的研究

对辣根过氧化物酶(HRP)、H2O2和乙酰丙酮(ACAC)组成的三元醇促体系引发的丙烯酰胺(AAM)聚合进行了研究。在膨胀计中考察了反应温度和HRP、ACAC、H2O2及AAM初始浓度对酶促体系引发AAM聚合动力学行为的影响,确定了适宜的反应条件。用FTIR和GPC对聚合产物进行表征,得到的聚丙烯酰胺的数均分子量为10^5-10^6,分子量分布指教DI为2-3。     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.