眼镜蛇毒心脏毒素的毒理及机制

眼镜蛇毒中含丰富的心脏毒素(Cardiotoxin,简称CTx),已分离提纯近60种,每种蛇毒中含2—4种CTx。1984年杜雨苍从广东产中华眼镜蛇毒(Naja Naja atra)中分离出该毒的第五种CTx,并命名为“细胞膜毒素     

眼镜蛇神经毒的免疫化学研究（摘要）

台湾产的眼镜蛇(Naja naja)的蛇毒经分离所得结晶体,属强碱性的突触后神经毒素,分子量为7000,是双硫键结合的多肽物,(如图1)     

眼镜蛇毒抗炎成分研究概况

<正>蛇毒是一种天然的生物学资源,是由蛇毒腺分泌的混合物,主要用于防卫和消化捕获的食物。蛇毒具有特殊的腥味,弱酸,其中含有多种生物活性物质,属于生物毒素。主要含神经毒素、心脏毒素、蛇毒因子和神经生长因子等,不同蛇种分泌的蛇毒成分也有所差异。蛇毒含水量在70%左右,每100ml毒汁中可得干毒20~29g。蛇毒的干物质中90%以上是蛋白质,是其毒性和生物学活性的主要成分。祖国传统医学认为,眼镜蛇及其毒性成分可通经络,祛风湿,并具有强     

中华眼镜蛇心脏毒素(CardiotoxinⅢ)的克隆及其在大肠杆菌和酵母中的表达

心脏毒素cardiotoxinⅢ（CTXⅢ）是中华眼镜蛇毒主要组分之一,根据Genbank中已有的CTXs序列设计特异性引物,从中华眼镜蛇毒中克隆出208bp的CTXⅢ片段,并将该基因片段分别克隆至大肠杆菌His—patch ThioredoxinB载体中,重组CTXⅢ经渗透休克分泌至胞外。将CTXⅢ基因插入酵母pPIC9K分泌型表达载体重组表达,N端带有3个氨基酸（GYT）残基的重组CTXⅢ（rCTXⅢ）分泌量达9．5mg／L,经一步凝胶过滤纯化,其纯度达90％以上,纯化率达65％。经细胞毒性实验检测,纯化的rCTXⅢ 12h的IC50为4．66μg／ml,证实重组蛋白具有良好的生物学活性。     

中华眼镜蛇心脏毒素（cardiotoxinⅢ, CTXⅢ）的克隆及其在大肠杆菌和酵母中的表达

心脏毒素cardiotoxinⅢ (CTXⅢ)是中华眼镜蛇毒主要组分之一,根据Genbank中已有的CTXs序列设计特异性引物,从中华眼镜蛇毒中克隆出208bp的CTXⅢ片段,并将该基因片段分别克隆至大肠杆菌His-patch ThioredoxinB载体中,重组CTXⅢ经渗透休克分泌至胞外。将CTXⅢ基因插入酵母pPIC9K分泌型表达载体重组表达,N端带有三个氨基酸（GYT）残基的重组CTXⅢ（rCTXⅢ）分泌量达9.5mg/L,经一步凝胶过滤纯化,其纯度达90％以上,纯化率达65％。经细胞毒性实验检测,纯化的rCTXⅢ 12h的IC50为4.66?g/ml,证实重组蛋白具有良好的生物学活性。     

MTT法测定眼镜蛇毒细胞毒素的抗癌活性

目的测定眼镜蛇毒细胞毒素（Ｃｏｂｒａｖｅｎｏｍｃｙｔｏｔｏｘｉｎ,ＣＶ－ＣＴＸ）对体外培养的人癌细胞的杀伤作用。方法溴化二苯四偶氮盐（ＭＴＴ）比色法。结果ＣＶ－ＣＴＸ对ＳＧＣ－７９０１,Ｂｅｌ－７４０２,Ｋ５６２和Ｕ９３７４种人癌细胞有很强的杀伤作用,量效关系明显,ＩＣ５０分别为４．１０,２．０８,０．２９和０．１７μｇ／ｍｌ。结论ＭＴＴ法检测ＣＶ－ＣＴＸ的抗癌活性,操作简便、快速和准确。     

蓝色染料配基亲和纯化眼镜蛇心脏毒素的研究

探索了蓝色染料（Cibacron Blue F3G-A）亲和分离中华眼镜蛇心脏毒素的可能性。采用环氧基活化法制备蓝色染料亲和介质,中性条件下提取眼镜蛇粗毒中的心脏毒素。Tricine系统SDS-PAGE多肽电泳和Lowry法蛋白定量分析纯化效果,发现蓝色染料琼脂糖一步纯化中华眼镜蛇心脏毒素的纯度达到84%,结合量为6.9mg/ml介质。这是首次利用小分子亲和配基纯化心脏毒素。与生物大分子配基相比,活性染料分子具有价格便宜,易于合成,性质稳定,不易降解和适合大规模生产等优点。     

眼镜蛇毒细胞毒素的抗肿瘤作用

目的　研究眼镜蛇毒细胞毒素（ Ｃ Ｖ Ｃ Ｔ Ｘ）的体内抗肿瘤作用。方法　小鼠皮下、腹腔接种 Ｓ１８０ 、 Ｅ Ａ Ｃ后, 于接种部位注射不同剂量的 Ｃ Ｖ Ｃ Ｔ Ｘ, 每天 １ 次, 连续１０ 天, 观察瘤重抑制率和生命延长率。结果　适当剂量（０２～０８ｍ ｇ／ｋｇ） 的 Ｃ Ｖ Ｃ Ｔ Ｘ 能明显抑制肿瘤的生长 （ Ｐ＜ ００１）,小鼠的存活时间明显延长（ Ｐ ＜ ００１）。结论　 Ｃ Ｖ Ｃ Ｔ Ｘ 在小鼠体内对 Ｓ１８０ 、 Ｅ Ａ Ｃ有明显地抗肿瘤作用。     

眼镜蛇甲状腺结构的年周期变化律

本文报道眼镜蛇甲状腺结构的年周期变化规律;发现：（１）眼镜蛇甲状腺的滤泡、滤泡柱状上皮和吞饮泡的总数均值皆近似单峰曲线的年周期变化。滤泡、滤泡柱状上皮和吞饮泡的总数均值的高峰时间分别为６月１７日、５月２７日和５月３０日。眼镜蛇甲状腺结构３项指标总数均值的高峰期处于血浆ＴＳＨ浓度高峰期后,血浆Ｔ３,Ｔ４浓度高峰期前。     

Cobra Venom Contains a Protein of the CRISP Family

Amino acid sequences of several fragments of the 25k protein (molecular mass 24 953 Da) previously isolated from cobra Naja kaouthia(Kukhtina et al.,Bioorg. Khim., 2000, vol. 26, pp. 803–807) were determined. Their comparison with the primary structures of known proteins showed that the 25k protein belongs to the CRISP family and is the first protein of this type identified in cobra venoms.     

Proteomic analysis and antivenomics study of Western India Naja naja venom: correlation between venom composition and clinical manifestations of cobra bite in this region

Background: Snakebite is a severe problem in the tropical countries including Indian subcontinent. Premier cases of cobra bites are being reported from western India (WI).

Research design and methods: The proteome of WI N. naja venom (NnV) was deciphered by high resolution mass spectrometry analysis of venom, further fractionated by gel filtration (GF) or RP-HPLC followed by SDS-PAGE and then tandem mass spectrometric analysis of protein bands. The efficacy of commercial polyantivenom (PAV) towards WINnV was assessed by ELISA, immuno-blot, neutralization, and venom-PAV immunoaffinity chromatography studies.

Results: Proteomic analysis of WINnV, GF fractions, and SDS-PAGE protein bands of RP-HPLC and GF peaks identified 14, 34, 40, and 54, distinct proteins, respectively, when searched against Elapidae database. The biochemical properties of WINnV correlated well with its proteome composition and pathophysiology of cobra envenomation, including neuroparalysis. This study also highlighted the differences in proteome composition between WINnV and previously reported Eastern India NnV. The tested antivenoms exhibited poor immuno-recognition and neutralization of low molecular mass proteins (<20 kDa), such as three-finger toxins, the major class of protein in WINnV.

Conclusion: Improvements in production protocols of antivenoms is the necessity of the hour, supplemented with antibodies raised against the poorly recognized toxins.     

Proteome analysis of snake venom toxins: pharmacological insights

Snake venoms are an extremely rich source of pharmacologically active proteins with a considerable clinical and medical potential. To date, this potential has not been fully explored, mainly because of our incomplete knowledge of the venom proteome and the pharmacological properties of its components, in particular those devoid of enzymatic activity. This review summarizes the latest achievements in the determination of snake venom proteome, based primarily on the development of new strategies and techniques. Detailed knowledge of the venom toxin composition and biological properties of the protein constituents should provide the scaffold for the design of new more effective drugs for the treatment of the hemostatic system and heart disorders, inflammation, cancer and consequences of snake bites, as well as new tools for clinical diagnostic and assays of hemostatic parameters.     

Characterization of diphtheria toxin's catalytic domain interaction with lipid membranes

In response to a low environmental pH and with the help of the B fragment (DTB) the catalytic domain of diphtheria toxin (DTA) crosses the endosomal membrane to inhibit protein synthesis. In this study, we investigated the interaction of DTA with lipid membranes by biochemical and biophysical approaches. Data obtained from proteinase K and trypsin digestion experiments of membrane-inserted DTA suggested that residues 134-157 may adopt a transmembrane orientation and residues 77-100 could be membrane-associated, adopting either a surface or a transmembrane orientation. Fourier transform infrared spectroscopy analysis (FTIR) was used to characterize the secondary and tertiary structure of DTA along its pathway, from the native secreted form at pH 7.2 to the refolded structure at neutral pH after interaction with and desorption from a lipid membrane. We found that the association of DTA with lipid membranes at low pH was characterized by an increase of β-sheet structures and that the refolded structure at neutral pH after interaction with the membrane was identical to the native structure at the same pH. We also investigated the desorption of DTA from the membrane at neutral pH as a function of temperature. Although a complete desorption was observed at 37 °C, no desorption took place at 4 °C. A model of translocation involving the possibility that DTA might insert one or several transient transmembrane domains during translocation is discussed.     

G-protein coupled receptor structure

Because of their central role in regulation of cellular function, structure/function relationships for G-protein coupled receptors (GPCR) are of vital importance, yet only recently have sufficient data been obtained to begin mapping those relationships. GPCRs regulate a wide range of cellular processes, including the senses of taste, smell, and vision, and control a myriad of intracellular signaling systems in response to external stimuli. Many diseases are linked to GPCRs. A critical need exists for structural information to inform studies on mechanism of receptor action and regulation. X-ray crystal structures of only one GPCR, in an inactive state, have been obtained to date. However considerable structural information for a variety of GPCRs has been obtained using non-crystallographic approaches. This review begins with a review of the very earliest GPCR structural information, mostly derived from rhodopsin. Because of the difficulty in crystallizing GPCRs for X-ray crystallography, the extensive published work utilizing alternative approaches to GPCR structure is reviewed, including determination of three-dimensional structure from sparse constraints. The available X-ray crystallographic analyses on bovine rhodopsin are reviewed as the only available high-resolution structures for any GPCR. Structural information available on ligand binding to several receptors is included. The limited information on excited states of receptors is also reviewed. It is concluded that while considerable basic structural information has been obtained, more data are needed to describe the molecular mechanism of activation of a GPCR.     

广东眼镜蛇蛇毒与眼镜王蛇蛇毒冻干粉的鉴别及质量控制的研究 V．广东眼镜蛇蛇毒与眼镜王蛇蛇毒的氨基酸分析

本文采用日立８３５－５０型氨基酸自动分析仪测定了广东眼镜蛇蛇毒与眼镜王蛇蛇毒的氨基酸成分,结果表明两种蛇毒的氨基酸组成基本相同,但多种氨基酸的含量存在明显差异,为蛇毒鉴别和质控提供实验依据。     

NMR structure and dynamics of recombinant wild type and mutated jerdostatin, a selective inhibitor of integrin α1β1

NMR analysis of four recombinant jerdostatin molecules was assessed to define the structural basis of two naturally occurring gain-of-function events: C-terminal dipeptide processing and mutation of the active residue K21 to arginine. Removal of the highly mobile and a bulky C-terminal dipeptide produced pronounced chemical shift changes in the sequentially unconnected but spatially nearby α(1)β(1) inhibitory loop. Analysis of chemical shift divergence and (15)N backbone relaxation dynamics indicated differences in motions in the picosecond to nanosecond time scale, and the higher T(2) rate of S25, S26, and H27 of rJerK21 point to a slowdown in the microsecond to millisecond motions of these residues when compared with rJerR21. The evidence presented in this article converges on the hypothesis that dynamic differences between the α(1)β(1) recognition loops of rJerR21 and rJerK21 may influence the thermodynamics of their receptor recognition and binding. A decrease in the μs-ms time scale may impair the binding affinity by reducing the rate of possible conformations that the rJerK21 can adopt in this time scale.     

New insights into the structure and oligomeric state of the bacterial multidrug transporter EmrE: an unusual asymmetric homo-dimer

EmrE is a small multidrug transporter that contains 110 amino acid residues that form four transmembrane alpha-helices. The three-dimensional structure of EmrE has been determined from two-dimensional crystals by electron cryo-microscopy. EmrE is an asymmetric homo-dimer with one substrate molecule bound in a chamber accessible laterally from one leaflet of the lipid bilayer. Evidence from substrate binding analyses and analytical ultracentrifugation of detergent-solubilised EmrE shows that the minimum functional unit for substrate binding is a dimer. However, it is possible that EmrE exists as a tetramer in vivo and plausible models are suggested based upon analyses of two-dimensional crystals.     

Structures of the FXYD regulatory proteins in lipid micelles and membranes

The FXYD membrane proteins constitute a family of conserved auxiliary subunits of the Na,K-ATPase, and have been the focus of recent attention due to their ability to finely regulate the activity of the enzyme complex in various physiological settings. In this review we describe the structures of the proteins, as well as their dynamics and their associations with the lipid bilayer membrane, which we have recently determined by NMR spectroscopy. Although the proteins are relatively small, their genes contain as many as six to nine small exons, and the coincidence of structured protein segments with their genetic elements suggests assembly from discrete structural modules through exon shuffling. The three-dimensional structures and backbone dynamics provide the foundation for understanding their intra-membrane association with the Na,K-ATPase α subunit, and the structure of FXYD1 suggests a mechanism whereby the phosphorylation of conserved Ser residues, by protein kinases A and C, could induce a conformational change in the cytoplasmic domain of the protein, to modulate its interaction with the α subunit.