共查询到20条相似文献，搜索用时 31 毫秒
1.
A monoclonal antibody bound to a protein antigen slows the rate of chemical modification of amino acid residues located at the epitope. By comparing the degree of acetylation of 18 lysine and 7 threonine residues in free and antibody-bound horse cytochrome c, a discontiguous, conformational epitope was characterized on this protein antigen. The new approach is particularly suitable to probe discontiguous and conformational epitopes, which are difficult to analyze by other procedures. 相似文献
2.
Fluorescence properties of calmodulin-binding peptides reflect alpha-helical periodicity 总被引：9，自引：0，他引：9
K T O'Neil H R Wolfe S Erickson-Viitanen W F DeGrado 《Science (New York, N.Y.)》1987,236(4807):1454-1456
A basic amphiphilic alpha-helix is a structural feature common to many calmodulin-binding peptides and proteins. A set of fluorescent analogues of a very tight binding inhibitor (dissociation constant of 200 picomolar) of calmodulin has been synthesized. The fluorescent amino acid tryptophan has been systematically moved throughout the sequence of this peptide. The fluorescence properties for the peptides repeat every three to four residues and are consistent with the periodicity observed for an alpha-helix. 相似文献
3.
In vivo half-life of a protein is a function of its amino-terminal residue 总被引：108，自引：0，他引：108
When a chimeric gene encoding a ubiquitin-beta-galactosidase fusion protein is expressed in the yeast Saccharomyces cerevisiae, ubiquitin is cleaved off the nascent fusion protein, yielding a deubiquitinated beta-galactosidase (beta gal). With one exception, this cleavage takes place regardless of the nature of the amino acid residue of beta gal at the ubiquitin-beta gal junction, thereby making it possible to expose different residues at the amino-termini of the otherwise identical beta gal proteins. The beta gal proteins thus designed have strikingly different half-lives in vivo, from more than 20 hours to less than 3 minutes, depending on the nature of the amino acid at the amino-terminus of beta gal. The set of individual amino acids can thus be ordered with respect to the half-lives that they confer on beta gal when present at its amino-terminus (the "N-end rule"). The currently known amino-terminal residues in long-lived, noncompartmentalized intracellular proteins from both prokaryotes and eukaryotes belong exclusively to the stabilizing class as predicted by the N-end rule. The function of the previously described posttranslational addition of single amino acids to protein amino-termini may also be accounted for by the N-end rule. Thus the recognition of an amino-terminal residue in a protein may mediate both the metabolic stability of the protein and the potential for regulation of its stability. 相似文献
4.
Conserved folding in retroviral proteases: crystal structure of a synthetic HIV-1 protease 总被引：57，自引：0，他引：57
A Wlodawer M Miller M Jaskólski B K Sathyanarayana E Baldwin I T Weber L M Selk L Clawson J Schneider S B Kent 《Science (New York, N.Y.)》1989,245(4918):616-621
The rational design of drugs that can inhibit the action of viral proteases depends on obtaining accurate structures of these enzymes. The crystal structure of chemically synthesized HIV-1 protease has been determined at 2.8 angstrom resolution (R factor of 0.184) with the use of a model based on the Rous sarcoma virus protease structure. In this enzymatically active protein, the cysteines were replaced by alpha-amino-n-butyric acid, a nongenetically coded amino acid. This structure, in which all 99 amino acids were located, differs in several important details from that reported previously by others. The interface between the identical subunits forming the active protease dimer is composed of four well-ordered beta strands from both the amino and carboxyl termini and residues 86 to 94 have a helical conformation. The observed arrangement of the dimer interface suggests possible designs for dimerization inhibitors. 相似文献
5.
Amino acid replacements that compensate for a large polypeptide deletion in an enzyme 总被引：1，自引：0，他引：1
Deletion of more than 400 amino acids from the carboxyl terminus of an enzyme causes a severe reduction in catalytic activity. Selected point mutations within the residual protein partially reverse the effects of the missing segment. The selection can yield mutants with activities at least ten times as high as those of the starting polypeptides. One well-characterized mutation, a single amino acid replacement in the residual polypeptide, increases the catalytic activity of the polypeptide by a factor of 5. The results suggest substantial potential for design of protein elements to compensate for missing polypeptide sequences. They also may reflect that progenitors of large aminoacyl-tRNA (transfer RNA) synthetases--one of which was used in these studies--were themselves much smaller. 相似文献
6.
Structural features that stabilize halophilic malate dehydrogenase from an archaebacterium 总被引：1，自引：0，他引：1
The high-resolution structure of halophilic malate dehydrogenase (hMDH) from the archaebacterium Haloarcula marismortui was determined by x-ray crystallography. Comparison of the three-dimensional structures of hMDH and its nonhalophilic congeners reveals structural features that may promote the stability of hMDH at high salt concentrations. These features include an excess of acidic over basic residues distributed on the enzyme surface and more salt bridges present in hMDH compared with its nonhalophilic counterparts. Other features that contribute to the stabilization of thermophilic lactate dehydrogenase and thermophilic MDH-the incorporation of alanine into alpha helices and the introduction of negatively charged amino acids near their amino termini, both of which stabilize the alpha helix as a result of interaction with the positive part of the alpha-helix dipole-also were observed in hMDH. 相似文献
7.
黑灵芝(Ganoderma astum)是灵芝家族中一个重要成员,克隆和分析黑灵芝免疫调节蛋白基因,可为进一步了解真菌免疫调节蛋白在种群中的分布打下基础。以黑灵芝为材料,采用同源克隆方法,对真菌免疫调节蛋白(FIPs)基因进行PCR扩增,并对其核苷酸编码序列进行了生物信息学分析。结果表明:黑灵芝真菌免疫调节蛋白基因序列包含336bp,可编码111个氨基酸残基,命名为FIP-gas。FIP-gas分子量为12.4kD,理论等电点为4.80,符合FIPs的特性,是FIPs家族一新成员。对FIP-gas进行序列分析发现其氨基酸序列具有FIPs的保守序列模式,与紫灵芝(G.japoncium)、紫芝(G.sinensis)、小孢灵芝(G.microsporum)、赤灵芝(G.lucidum)、松杉灵芝(G.tsugae)、金针菇(Flammulina velutipes)及草菇(Volvariella volvacea)的FIP序列的同源性分别为99%、98%、87%、86%、86%、61%、55%。系统进化树分析表明黑灵芝的FIP与紫芝的FIP亲缘性最高,与金针菇和草菇的FIP亲缘性相对较远。该研究为进一步了解免疫调节蛋白在灵芝种群中的分布提供了较详细的数据。 相似文献
8.
根据已公布的Hom eobox基因氨基酸序列保守区设计简并引物,利用PCR技术从内蒙古绒山羊血液基因组DNA中扩增Hom eobox基因家族成员。目的基因片段纯化后连接到pGEM-T载体上,经鉴定得到重组质粒。将110个重组质粒进行测序,测序结果通过与GenBank中序列比对分析,确定86条序列为Hom eobox基因,得到14个Hom eobox基因家族成员:Hoxa4,Hoxa5,Hoxa6,Hoxa7,Hoxb1,Hoxb2,Hoxb3,Hoxb6,Hoxb7,Hoxc6,Hoxd1,Hoxd3,Gbx1,Gbx2。每个基因片段由117个核苷酸组成,编码39个氨基酸。氨基酸序列非常保守,和其他物种的同源性非常高。 相似文献
9.
The prediction of protein structure from amino acid sequence is a grand challenge of computational molecular biology. By using a combination of improved low- and high-resolution conformational sampling methods, improved atomically detailed potential functions that capture the jigsaw puzzle-like packing of protein cores, and high-performance computing, high-resolution structure prediction (<1.5 angstroms) can be achieved for small protein domains (<85 residues). The primary bottleneck to consistent high-resolution prediction appears to be conformational sampling. 相似文献
10.
根据已发表的Bm86基因序列,设计表达型引物,利用RT-PCR技术,从微小牛蜱饥饿幼蜱的研磨物中扩增Bm86基因,将PCR产物连入pGEM-T Easy载体,构建重组克隆载体pGEM-T easy-Bm86.测序分析表明:克隆的微小牛蜱Bm86基因序列与GenBank上登录的Bm86基因的核苷酸和氨基酸序列的同源性分别为97%和95.6%.然后对重组克隆载体pGEM-T easy-Bm86进行双酶切,获得带有粘性末端的Bm86基因片段,并将此片段定向亚克隆入原核表达载体pGEX-4T-1,构建重组原核表达载体pGEX-4T-1-Bm86,将其转化到BL21宿主菌中,用IPTG进行诱导表达.SDS-PAGE检测表明表达产物为分子量为88 Ku的融合蛋白,目的蛋白约占蛋白总量的39%,表达量约为1.08 mg/mL.Western blot分析表明此表达产物能被兔抗微小牛蜱阳性血清所识别. 相似文献
11.
A synaptic vesicle protein with a novel cytoplasmic domain and four transmembrane regions 总被引：29，自引：0，他引：29
T C Südhof F Lottspeich P Greengard E Mehl R Jahn 《Science (New York, N.Y.)》1987,238(4830):1142-1144
Complementary DNA and genomic clones were isolated and sequenced corresponding to rat and human synaptophysin (p38), a major integral membrane protein of synaptic vesicles. The deduced amino acid sequences indicate an evolutionarily highly conserved protein that spans the membrane four times. Both amino and carboxyl termini face the cytoplasm, with the latter containing ten copies of a tyrosine-rich pentapeptide repeat. The structure of synaptophysin suggests that the protein may function as a channel in the synaptic vesicle membrane, with the carboxyl terminus serving as a binding site for cellular factors. 相似文献
12.
川芎甜菜碱醛脱氢酶基因的克隆及序列分析 总被引：1，自引：0，他引：1
以川芎(Liqusticum churning Franch Hort)为材料,采用RT-PCR和RACE方法,从新鲜的嫩叶中克隆出甜菜碱醛脱氢酶(betaine aldehyde dehydrogenase,BADH)基因的cDNA序列。克隆到的cDNA序列全长为2 211 bp,编码一条由508个氨基酸残基组成的多肽,其核酸序列与人参的BADH基因的cDNA序列同源性为86%,对应编码氨基酸序列同源性为91%。将得到的序列提交GenBank,序列号为HM352764。与其他植物BADH的氨基酸序列比对,川芎BADH具有相同功能区域,包括N-端信号肽、底物结合及酶催化位点,因而可以参与甜菜碱的合成反应。对川芎BADH与其他植物BADH的氨基酸序列的进化分析表明,其与五加科人参的同源性较近。 相似文献
13.
枸杞胆碱合成关键酶基因PEAMT的克隆及生物信息学分析 总被引：1，自引：0，他引：1
利用RT-PCR和RACE结合的方法,获得了枸杞磷酸乙醇胺N-甲基转移酶PEAMT基因cDNA全序列(命名为LbPEAMT).LbPEAMT cDNA全长1 863 bp,开放读码框1 497 bp,编码一个由498个氨基酸构成的多肽,理论分子量为56.53 kDa,等电点pⅠ为5.50.通过多种序列比对,该基因编码的氨基酸序列与番茄PEAMT氨基酸的相似性为93％.二级结构预测LbPEAMT蛋白由44.98％的α-螺旋、17.67％的延伸链、6.63％的β-转角和30.72％的不规则卷曲组成.LbPEAMT是一个亲水蛋白.含有2个S-腺苷甲硫氨酸依赖催化活性结构域,分别位于N端65-164 aa和C端290-392aa.每个活性区都包含有4个部分基序,分别为Ⅰ、post Ⅰ、post Ⅱ和post Ⅲ.LbPEAMT的这2个活性区在蛋白、磷脂和小分子甲基转移酶中都是相对保守的. 相似文献
14.
Molecular structure of troponin C from chicken skeletal muscle at 3-angstrom resolution 总被引：19，自引：0，他引：19
M Sundaralingam R Bergstrom G Strasburg S T Rao P Roychowdhury M Greaser B C Wang 《Science (New York, N.Y.)》1985,227(4689):945-948
The x-ray structure of chicken skeletal muscle troponin C (TnC), the Ca2+-binding subunit of the troponin complex, shows that the protein is about 70 angstroms long with an unusual dumbbell shape. The carboxyl and amino domains are separated by a single long alpha helix of about nine turns. Only the two high-affinity Ca2+-Mg2+ sites of the COOH-domain are occupied by metal ions resulting in conformational differences between the COOH- and NH2-domains. These differences are probably important in the triggering of muscle contraction by TnC. Also the structure of TnC is relevant in understanding the function of other calcium-regulated proteins, in particular that of calmodulin because of its strong similarity in amino acid sequence. 相似文献
15.
从核桃(Juglans regia)中首次克隆得到黄烷酮3-羟化酶基因的cDNA片段,并命名为JrF3H,GenBank登录号为FJ966204.JrF3H长1 029 bp,编码342个氨基酸.蛋白质序列多重比对结果表明,推导的JrF3H蛋白质与其他植物F3H蛋白质具有很高的相似性,JrF3H蛋白质与茶学、拟南芥、大豆、烟草、小麦和银杏F3H蛋白质序列的同源性分别为86%、85%、85%、82%、80%和79%.此外,JrF3H在相似的位置存在结合亚铁离子和酮戊二酸的保守位点.F3H系统进化树表明,JrF3H与乔木类植物的F3H基因聚类关系最近.JrF3H基因的克隆将有助于弄清该基因在核桃黄酮代谢途径中所起的作用. 相似文献
16.
【目的】制备非洲猪瘟病毒（African swine fever virus,ASFV）p30蛋白的单克隆抗体（monoclonal antibodies,MAbs）并初步分析其所识别的线性抗原表位,为ASFV及其抗体检测方法的建立及p30蛋白结构和功能的研究奠定基础。【方法】将原核表达并纯化的p30重组蛋白作为免疫原,免疫6—8周龄BALB/c雌鼠,每两周免疫1次,共免疫3次,首次免疫是抗原与等体积的弗氏完全佐剂乳化后免疫,第二次和第三次免疫与等体积的弗氏不完全佐剂乳化,3次免疫后1 w断尾采血,间接酶联免疫吸附试验（ELISA）检测血清抗体效价,选择血清效价最高的小鼠进行加强免疫,3 d后取小鼠脾淋巴细胞与SP2/0骨髓瘤细胞按照4﹕1的比例使用PEG进行常规细胞融合。利用重组p30蛋白作为包被抗原,间接ELISA筛选阳性杂交瘤细胞,有限稀释法进行克隆纯化,直至筛出能够稳定分泌抗体的MAbs。将ASFV接种于猪肺泡巨噬细胞,以筛选的MAbs为一抗、兔抗鼠HRP-IgG为二抗,进行间接免疫荧光试验（IFA）。将感染和未感染ASFV的细胞沉淀处理后进行 SDS-PAGE并转印至硝酸纤维素膜,分别以IFA鉴定为阳性的MAbs上清为一抗、兔抗鼠HRP-IgG为二抗,进行Western blotting分析,筛选获得p30 MAbs。根据已知序列设计引物扩增p30ab与p30bc两段截短基因,其中p30ab代表由第86—153位氨基酸残基的截短体,p30bc代表由第120—187位氨基酸残基的截短体,原核表达部分重叠的截短p30蛋白,最终获得重组蛋白GST-p30ab与重组蛋白GST-p30bc。分别以GST-p30ab和GST-p30bc融合蛋白为包被抗原,以5株MAbs为一抗,以兔抗鼠HRP-IgG为二抗, 通过间接ELISA方法初步定位p30蛋白的抗原表位。【结果】以纯化的重组蛋白为包被抗原,经间接ELISA试验筛选出25株可分泌抗重组 p30蛋白的杂交瘤细胞株。IFA结果显示,5株MAbs（8F4、1D3、1H2、6C3和8E11）与ASFV感染的猪肺泡巨噬细胞IFA 试验呈阳性;Western blotting结果显示,5株MAbs均能够与ASFV感染的细胞呈阳性反应,与未感染病毒的细胞呈阴性反应。试验构建的p30截短体重组蛋白GST-p30ab以可溶和包涵体两种形式表达,而GST-p30bc仅以包涵体形式表达,以两组截短体融合蛋白为包被抗原,通过间接ELISA检测出MAbs 8F4、1H2和6C3与两个重组蛋白均能有效结合,证明MAbs 8F4、1H2和6C3抗原识别区域为两组截短蛋白重叠区域,即第120—153位氨基酸;MAbs 8E11与1D3则只能与GST-p30ab蛋白结合, 证明MAbs 8E11与1D3抗原识别区域为两个重组蛋白的非重叠区域,即第86—119位氨基酸。【结论】本研究可溶性地表达了p30蛋白的第86—153位氨基酸截短体重组蛋白,制备了5株p30 MAbs,定位到2个p30蛋白抗原表位。结合ELISA和IFA,可建立十分可靠的ASFV及其抗体的检测手段。 相似文献
17.
不同氮水平对高油玉米吉油一号籽粒产量及其营养品质的影响 总被引：15，自引：0，他引：15
不同氮营养水平对高油玉米吉油一号籽粒产量、蛋白质、氨基酸和油脂的影响的研究表明,不同氮营养水平对高油玉米籽粒产量影响较大,施氮增产10.5%～22.9%。在本试验条件下的经济最佳施氮(N)量为180.3 kg·ha-1。不同施氮水平较不施氮均能明显增加高油玉米籽粒蛋白质及其组分中醇溶蛋白和谷蛋白含量,分别增加7.1%～13.3%(平均10.6%)、22.1%～39.1%(平均29.9%)和25.0%～40.7%(平均35.0%),其中施氮175 kg·ha-1时蛋白质含量最高(10.75%),施氮125 k 相似文献
18.
为了解烟草种子萌发时可溶性蛋白质含量与游离氨基酸含量之间的关系,研究以烤烟K326种子和白肋烟TN86种子为材料,采用紫外分光光度法,探索了烤烟K326种子和白肋烟TN86种子从萌发时第0小时至第336小时共十六个时期的萌发过程中,可溶性蛋白质含量及游离氨基酸含量的变化规律。结果表明:烤烟K326种子可溶性蛋白质含量高峰,在第96小时达最大值,而白肋烟TN86种子可溶性蛋白质含量高峰,则在168小时达最大值;烤烟K326种子和白肋烟TN86种子游离氨基酸含量最大值,均在第336小时;两种类型烟草种子萌发期间种子中可溶性蛋白质含量与游离氨基酸含量之间均呈极显著正相关。 相似文献
19.
Enhancing boll protein synthesis and carbohydrate conversion by the application of exogenous amino acids at the peak flowering stage increased the boll Bt toxin concentration and lint yield in cotton 
下载免费PDF全文
下载免费PDF全文 《农业科学学报》2023,22(6):1684-1694
In Bacillus thuringenesis (Bt) transgenic cotton, the cotton boll has the lowest insecticidal protein content when compared to the other organs. The present study investigated the effects of amino acid spray application at the peak flowering stage on the cotton boll Bt toxin concentration and yield formation. Boll protein synthesis and carbohydrate conversion were also studied to reveal the fundamental mechanism. Three treatments (i.e., CK, the untreated control; LA1, five amino acids; LA2, 21 amino acids) were applied to two Bt cultivars of G. hirsutum (i.e., the hybrid Sikang 3 and the conventional Sikang 1) in the cotton-growing seasons during 2017 and 2018. Amino acid spray application at the peak flowering stage resulted in an increase of 5.2–16.4% in the boll Bt protein concentration and an increase of 5.5–11.3% in the seed cotton yield, but there was no difference between the two amino acid treatments. In addition, amino acid applications led to increases in the amino acid content, soluble protein content, glutamate pyruvate transaminase (GPT) activity, glutamate oxaloacetate transaminase (GOT) activity, glucose content, fructose content and soluble acid invertase (SAI) activity. This study also found that Bt protein content, enhanced boll number and the weight of opened bolls were closely related to carbon and nitrogen metabolism. The Bt protein content had significant linear positive correlations with amino acid and soluble protein contents. Enhanced boll number had significant linear positive correlations with the GPT and GOT activities from 15–25 days after flowering (DAF). The weight of opened bolls from 55–65 DAF had a significant linear positive correlation with the SAI activity. These results indicate that the enhancement of boll protein synthesis and carbohydrate conversion by amino acid application resulted in a simultaneous increase in the boll Bt protein concentration and cotton lint yield. 相似文献
20.
罗非鱼免疫球蛋白（IgM）重链基因全长cDNA序列分析 总被引：1，自引：0，他引：1
从已经构建的罗非鱼白细胞cDNA文库中测定获得罗非鱼免疫球蛋白（IgM）重链的eDNA序列,全长1885bp,有一个完整ORF阅读框长1770bp,5’UTR为29bp,3’-UTR为86bp,编码588个氨基酸。罗非鱼与大黄鱼、斜带石斑鱼、南极鳕鱼、乌鳢、鳜鱼、伯氏豚[鱼叚]虎鱼、牙鲆、花狼鱼、硬头鳟的IgM重链氨基酸序列有较高的同源性,最高达到69％,表明已经获得罗非鱼IgM重链基因;对所得氨基酸进行二级结构预测发现,罗非鱼IgM重链基因全长cDNA序列所编码的氨基酸分子量为41453．94Da。该试验结果为罗非鱼IgM重链基因功能的实验性鉴定工作奠定了基础。 相似文献