用基因工程方法制成人生长激素

去年七月,J A Martial等人和美国基因技术公司研究小组分别实验成功用遗传工程方法制造人生长激素。但他们所用的方法却不同。Martial等人先分离生长激素mRNA,经反转录法合成cDNA,cDNA经分子扩增后,插入表达性载体。这样大肠杆菌生产的是生长激素前体。这种前体需切掉多余的肽腱,才能     

人造激素已用于人体临床实验尿激酶细菌合成获得成功

初步材料证明,细菌制造的人生长激素具有天然产品的生物活性,但其活性还不及天然产品那样高,1980年在基因工程历史上细菌合成的人生长激素第一次注入到人体中,这是在英国伦敦出现的事,开始在健康人身上实验人造胰岛素(SN;118(4):53)这种胰岛素很有效地使血糖水平降低。以后继续在糖尿病患者进行类似的实验,可以预     

国际矿产化学公司打算使重组体猪生长激素商品化

国际矿产化学公司(IMC)希望最早在1988年能大规模生产重组体猪生长激素。猪生长激素将是为制造动物产品而建的100万美元的生物技术新设施的第一批产品。如果走运的话,设施的设计和建造将同时进行,届时 IMC 也将完成其开发工作和得到联邦政府的产品许可证。IMC 将根据与 Biogen 公司的许可协议生产生长激素,Biogen 公司几年前为 IMC 克隆了猪和牛的生长激素。     

人造激素已用于人体临床实验尿激酶细菌合成获得成功

初步材料证明,细菌制造的人生长激素具有天然产品的生物活性,但其活性还不及天然产品那样高,1980年在基因工程历史上细菌合成的人生长激素第一次注入到人体中,这是在英国伦敦出现的事,开始在健康人身上实验人造胰岛素(SN;118(4):53)这种胰岛素很有效地使血糖水平降低。以后继续在糖尿病患者进行类似的实验,可以预     

分泌型重组人生长激素的研制

从人脑垂体组织中克隆了人生长激素基因并构建了分泌型表达基因工程菌Ｅ．ｃｏｌｉＫ８０２／ｐＡＶＧＨ。研制的ｒｈＧＨ中试产品,各项技术指标均达到临床应用要求     

毕赤酵母高效分泌长效人生长激素的研究

目的:为了延长人生长激素(HGH)在血浆中的半衰期,构建了高效分泌表达人血清白蛋白(HSA)与HGH融合蛋白(HSA-HGH)的工程毕赤酵母菌株。方法:从人胎肝cDNA文库中扩增HSA基因,从HGH工程菌载体中扩增HGH基因,将其克隆至真核表达载体pHIL-D2,载体线性化后采用电击法转化毕赤酵母GS115。通过原位双层膜法筛选高效分泌表达菌株。分别采用SDS-PAGE和Western印迹鉴定融合蛋白。对工程酵母培养条件进行研究,发酵液经离子交换层析、亲和层析和分子筛层析纯化。纯化的蛋白经N端序列测定,分子量测定和等电聚焦电泳进行鉴定。冻干的蛋白制剂经食蟹猴试验进行药代动力学和药效动力学测试。结果:确立了工程酵母的最佳培养工艺,融合蛋白表达量达100mg/L。纯化后蛋白纯度达95%以上,得率达42%。融合蛋白与预期结果一致,经食蟹猴试验,显示有良好的生物活性,与等摩尔剂量的重组人生长激素相比,半衰期延长6.8倍,清除率慢44倍。结论:融合蛋白呈现明显的长效动力学特征,为开发重组长效人生长激素HSA-HGH融合蛋白药物(rHSA-HGH)奠定了基础。     

人生长激素研究进展

综述了人生长激素的结构,及最近几年国内外对人生长激素在分子结构、基因改造、制备、提纯及检测等方面的最新进展和研究趋势,对各种可能影响生长激素分泌的因素进行了分析、讨论。     

在大肠杆菌中温度诱导高效表达猪生长激素

本实验构建了温度诱导的表达猪生长激素的表达载体,转化大肠杆菌N4830后,经温度诱导,获得了高效表达．由SDS-聚丙烯酰胺凝胶电泳及Westerm blot证实表达产物为猪生长激素,经扫描估测猪生长激素的表达量占大肠杆菌细胞全蛋白的30％左右。     

编码人生长激素的DNA序列在大肠杆菌中的直接表达

编码人生长激素的DNA通过用化学合成的DNA与酶促制备的CDNA连接而建立。这一“杂化物”基因在乳糖操纵子控制下在大肠杆菌中表达,产生的肽在大小和免疫学性质上具有成熟的人的生长激素的特性。 人生长激素(HGH)是垂体前叶合成的具有191个氨基酸的蛋白质。垂体机能减退 的侏儒因HGH缺陷而身材矮小,在儿童期使用人生长激素可以治疗这一缺陷症。另外,HGH在治疗各种创伤疾病如骨折、皮肤烧伤、溃疡等被证实是有效的。由于生长激素具种属专一性,人的尸体成为HGH的唯一来源。 生长激素mRNA的初级翻译产物是一个蛋白前体,含有与生长激素N末端相接的一段信号肽。这种信号或“前”序列是分泌蛋白的特征。对于大鼠生长激素(RGH),已经鉴定了由RGH mRNA制备的CDNA序列中前序列的26个氨基酸残基。由人生长激素cDNA序列获得的信息,我们设计并建立了一个细菌质粒,它可以在微生物细胞中指导合成大量的成熟HGH。     

家族性单纯生长激素缺乏症的分子生物学研究

家族性单纯生长激素缺乏症的分子生物学研究于丽莉,王亚新（上海第二医科大学生化教研室,上海２０００２５）关键词生长激素缺乏症,发病机理人的生长、发育和代谢与垂体分泌的一种１９１个氨基酸组成的激素──人生长激素（ｈＧＨ）有关,它的异常会导致人身体生长发育...     

Purification and characterization of human transcortin.

Human transcortin was purified to apparent homogeneity from plasma by a two-step procedure involving affinity and hydroxyapatite chromatography. The affinity gel incorporated denatured bovine serum albumin as the spacer and cortisol hemisuccinate as the ligand. Although isolated transcortin showed a propensity for spontaneous polymerization according to a geometric progression (1, 3, 9) only one band was observed on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Cortisol-binding activity of the isolated protein gave an apparent association constant of 2.5 X 10(8) M-1 at 4 degree C in equilibrium dialysis. Isoelectric focusing of purified native transcortin showed six discrete bands, five between pH 3.75 and 4.15 and another, possibly desialylated, at pH 6.15. Desialylated transcortin also gave six bands on isoelectric focusing, with pI values ranging from 4.90 to 6.30.     

Immunoaffinity chromatography as a means of purifying legumin from Pisum (pea) seeds.

The potential of immunoaffinity chromatography as a means of purifying legumin from a wide range of Pisum (pea) types was assessed. The method required small amounts of highly purified legumin from a single Pisum type, and this was obtained by salting out with (NH4)2SO4 followed by zonal isoelectric precipitation, ion-exchange chromatography on DEAE-cellulose and sucrose-density-gradient centrifugation. Some physiocochemical properties of purified legumin were determined, a number of which (Strokes radius, subunit molecular weights, subunit N-terminal residues and subunit molar ratios) have not previously been reported for Pisum legumin. Examination of Pisum legumin by two-dimensional gel isoelectric focusing/electrophoresis indicated the existence of extensive subunit heterogeneity, and polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate showed apparent variation in the nature of this heterogeneity from one Pisum variety to another. Despite this variation, immunoaffinity chromatography on immobilized anti-legumin (which was prepared by affinity chromatography on the immubolized purified legumin from the single Pisum type) was shown to be a generally applicable method for the purification of undegraded legumin from a range of pisum types, including two primate lines.     

Purification and some properties of rat intestinal ornithine decarboxylase

Ornithine decarboxylase (ODC) was induced in rat small intestine by treatment with hypotonic solution in vitro and purified by two procedures, a conventional procedure and an immunoaffinity procedure. SDS-polyacrylamide gel electrophoresis showed that the molecular weight of the preparation purified by the immunoaffinity procedure (Mr = 53,000) was slightly larger than that of the preparation obtained by the conventional procedure (Mr = 52,000). Values for the Km for L-ornithine (0.1 mM), the isoelectric point (5.4), and the final specific activity (5.1-5.5 x 10(5) nmol CO2/mg protein/30 min) of the two preparations were similar to those reported for the rat liver ODC. Addition of a protease inhibitor (limabean trypsin inhibitor) to the crude extract prevented the appearance of the smaller enzyme (Mr = 52,000) obtained by the conventional purification procedure. Our result indicates that the large enzyme is native ODC and the smaller one is a partial proteolysis product of native ODC.     

Characterization of intact and trypsin-digested biosynthetic human growth hormone by high-pressure liquid chromatography

The structural properties of purified human growth hormone (hGH) produced by Escherichia coli K-12 into which the hGH gene has been inserted have been fully characterized by high-pressure liquid chromatography of native hGH and tryptic digests of hGH. All of the tryptic peptides have been separated by high-pressure liquid chromatography and their sequence determined. Comparison of the primary structure with that of the purified pituitary-derived hGH has established the integrity of the biosynthetic hGH disulfide arrangement and amino acid sequence with the presence of an extra NH₂-terminal methionine.     

D-glucose dehydrogenase from Bacillus megaterium M 1286: purification, properties and structure.

1) Glucose dehydrogenase from Bacillus megaterium has been purified to a specific activity of 550 U per mg protein. The homogeneity of the purified enzyme was demonstrated by gel electrophoresis and isoelectric focusing. 2) The amino acid composition has been determined. 3) The molecular weight of the native enzyme was found to be 116000 by gel permeation chromatography, in good agreement with the values of 120000 and 118000, which were ascertained electrophoretically according to the method of Hedrick and Smith and by density gradient centrifugation, respectively. 4) In the presence of 0.1% sodium dodecylsulfate and 8M urea, the enzyme dissociates into subunits with a molecular weight of 30000 as determined by dodecylsulfate gel electrophoresis. These values indicate that the native enzyme is composed of four polypeptide chains, each probably possessing one coenzyme binding site, which can be concluded from fluorescent titration of the NADH binding sites. 5) In polyacrylamide disc electrophoresis, samples of the purified enzyme exhibit three bands of activity, which present the native (tetrameric) form of glucose dehydrogenase and two monomeric forms (molecular weight 30000), arising under the conditions of pH and ionic strength of this method. 6) The enzyme shows a sharp pH optimum at pH 8.0 in Tris/HCl buffer, and a shift of the pH optimum to pH 9.0 in acetate/borate buffer. The limiting Michaelis constant at pH 9.0 for NAD is 4.5 mM and 47.5 mM for glucose. The dissociation constant for NAD is 0.69 mM. 7) D-Glucose dehydrogenase is highly specific for beta-D-glucose and is capable of using either NAD or NADP. The enzyme is insensitive to sulfhydryl group inhibitors, heavy metal ions and chelating agents.     

Immunoaffinity purification of rat liver transketolase: evidence for multiple forms of the enzyme

Rat liver transketolase (TK) has been purified, in a single step, by immunoaffinity chromatography on specific TK antibodies covalently linked to Sepharose 4B. The procedure described also involves the raising and isolation of rabbit TK antibodies to the conventionally purified enzyme [F. Paoletti (1983) Arch. Biochem. Biophys. 222, 489-496]. Affinity chromatography allows a 100-fold purification of TK from the cell cytosol and a recovery of about 70% of the original activity. The TK isolated has a specific activity of 2.7-3.2 at 25 degrees C and migrates as a single band on polyacrylamide gel electrophoresis at pH 9.1. Multiple forms of the enzyme, with distinct pI values in the range 7-8, have been detected in purified preparations by means of analytical isoelectric focusing and staining for TK. No addition of either Mg2+ or thiamine pyrophosphate is required for the activity of the enzyme which, in the native form, exhibits a molecular weight of about 139,000. Two moles of thiamine pyrophosphate can be resolved for each mole of enzyme. Affinity TK preparations are virtually free of glyceraldehyde-3-phosphate dehydrogenase, pentose-phosphate epimerase, and isomerase, although slight contamination by phosphohexose isomerase may occur.     

Structure and properties of albumin Tokushima and its proteolytic processing by cathepsin B in vitro

Albumin Tokushima is a Japanese genetic variant of human serum albumin. Two homozygous and 6 heterozygous subjects with this variant were found in a family. Albumin Tokushima was purified from sera of the homozygous subjects. Its amino acid composition and amino-terminal sequence were determined and compared with those of a normal serum albumin. Albumin Tokushima with the amino-terminal sequence of Arg-Gly-Val-Phe-His-Arg-Asp-Ala-His-Lys-Ser-Glu-Val-Ala-His-Arg-Phe-Lys- Asp- Leu-Gly-Glu-Glu-Asn-Phe was found to be the same abnormal proalbumin as proalbumin Lille (Abdo, Y. et al. (1981) FEBS Lett. 131, 286-288). The isoelectric points of albumin Tokushima were pH 4.70 and 4.90 as compared with pH 5.05 and 5.25 of a normal serum albumin. Albumin Tokushima was converted to normal serum albumin by purified cathepsin B in vitro. Albumin Tokushima can bind Ni2+ at 4 degrees C but binds little at 37 degrees C.     

Purification of human liver fumarylacetoacetase using immunoaffinity chromatography

A method is described to purify fumarylacetoacetase from crude human liver extracts using immunoaffinity chromatography. Immobilized rabbit antibodies specific for beef liver fumarylacetoacetase were used as an immunoadsorbent. With this rapid and specific procedure human liver fumarylacetoacetase could be purified to apparent homogeneity. The molecular weight of native human liver fumarylacetoacetase is approximately 83000 as estimated by gel filtration. The two subunits have a molecular weight of approximately 41000, as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Purified human liver fumarylacetoacetase has a broad pH optimum with a maximum at pH 7.2 and a K_m = 2.1 μM towards fumarylacetoacetate.     

Isoelectric focusing studies of bacteriorhodopsin

Purified bacteriorhodopsin (BR) samples show a minimum of four isoelectric forms in immobilized pH gradient isoelectric focusing gels. The bands occur as doublets with isoelectric points (pI) centered at 5.20 (principal species) and 5.60. In typical preparations additional bands may be observed at 4.90, 5.07 and 5.50. Purple membrane (PM) was proteolyzed with papain to calibrate the pI shift produced by changing the number of charges on the protein. Asp-242 is removed during the first cleavage between residues 239 and 240 resulting in the loss of a single negative charge and a shift of the principal doublet by +0.35 pH units to pI 5.55. The second papain cleavage occurs between residues 231 and 232 which removes Glu-232, -234 and -237 and shifts the pI by +0.60 pH units to pI 6.10. The +0.60 pH shift upon the second papain cleavage is consistent with the loss of two negative charges and is supported by prior evidence that at least one of the three glutamate residues lost during the second proteolysis step is protonated and neutral in the intact protein. The native and proteolyzed products of BR retain the characteristic 550 nm absorption maxima for solubilized BR. A model for the structural origin of the pI heterogeneity of BR species in proteolyzed PM is presented.     

Purification and characterization of a novel glutathione S-transferase from Atactodea striata

A novel GST isoenzyme was purified from hepatopancreas cytosol of Atactodea striata with a combination of affinity chromatography and reverse-phase HPLC. The molecular weight of the enzyme was determined to be 24 kDa by SDS-PAGE electrophoresis and 48 kDa by gel chromatography, in combination with GST information from literature revealed that the native enzyme was homodimeric with a subunit of M(r) 24 kDa. The purified enzyme, exhibited high activity towards 1-chloro-2,4-dinitrobenzene (CDNB) and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). Kinetic analysis with respect to CDNB as substrate revealed a K(m) of 0.43 mM and V(max) of 0.24 micromol/min/mg and a specific activity of 108.9 micromol/min/mg. The isoelectric point of the enzyme was 5.5 by isoelectric focusing and its optimum temperature was 38 degrees C and the enzyme had a maximum activity at approximately pH 8.0. The amino acid composition was also determined for the purified enzyme.