多肽的固相合成法研究进展

介绍了多肽的固相合成法,包括多肽合成原理、发展简史、固相多肽合成的分类、合成中常用的树脂、合成步骤、合成过程中可能出现的副反应以及较长肽链、某些蛋白质的合成策略。     

海洋药物新技术研究进展

近年来生物研究技术的发展,为开发海洋药物提供了新的方法、思路和方向。介绍了海洋药物研究的新技术,包括生物筛选技术、多肽固相合成法、超临界流体色谱法生产技术,指出了海洋药物研究存在的问题,并对相关研究进行了展望。     

蛋白质的折叠调控与包涵体的形成

新合成的多肽链必须先经折叠和装配后形成特定的三维结构才有活性.分子伴侣和蛋白酶可有效地调控多肽链的正确折叠.然而,在多肽链的折叠过程中,往往也会产生一些折叠异常的蛋白,形成集聚体即包涵体.本文主要对蛋白质的折叠机制、分子伴侣和蛋白酶在折叠中的作用,以及集聚和包涵体的特性、形成机理等做一综述.     

大豆水解蛋白注射液的制备

蛋白质是机体维持生命活动的最基本的物质基础。在机体内,它们具有多种多样的生理功能,有的是酶,有的是抗体,有的是激素等。蛋白质的结构虽然极为复杂,但其基本结构都是由各种氨基酸分子借肽键相连所形成的多肽链所构成的。因此,氨基酸在生命过程中的重要性就是非常明显的了。目前巳发现的氨基酸达百余种,但构成机体的氨基酸却只有20多种。其中8种氨基酸是     

多肽简介及应用

多肽,是指分子结构介于氨基酸和蛋白质之间的一类化合物.氨基酸是组成多肽和蛋白质的基本基团.一般来讲,多肽的含义更广泛一些,多肽和蛋白质之间并没有严格的区分,多肽指由低于五十个氨基酸组成的化合物,如由三个氨基酸组成叫三肽,四个组成叫四肽,顺此类推;高于五十个氨基酸以上的化合物通常称为蛋白质,如:治疗糖尿病的药物胰岛素就是一种多肽,它由51个氨基酸组成,称为51肽.自1902年,伦敦大学医学院的Bayliss和Starling从动物的胃肠发现一种能引起胰腺分泌活动的物质,称为促胰液素(Secretin),这是人类第一次发现活性多肽物质.伴随着分子生物学、生物化学技术的飞速发展,多肽的研究取得了惊人的、划时代的进展,到目前为止,人们发现存在于生物体的多肽有数万种.     

口蹄疫病毒部分免疫功能肽段的合成、鉴定及免疫功能评价

利用微波多肽合成仪Liberty,合成O型口蹄疫病毒VP1 140~160和200~213氨基酸序列的两条肽段,并用高压液相色谱仪及质谱分析仪就合成的多肽片段进行分析纯化和鉴定;将合成的多肽片段作为半抗原与载体蛋白BSA偶联,免疫小鼠,进行血清制备和抗体效价测定.结果表明:成功合成了口蹄疫2条免疫功能短肽,其纯度均达到80%以上.半抗原成功与载体蛋白偶联;小鼠抗血清经过抗体效价检测证明半抗原与载体蛋白偶联组的抗体水平高于其余2个对照组,但是达不到免疫保护的水平.同时说明Liberty是一种操作简单、方便,合成效率高的多肽合成仪,可高效合成研究用多肽.     

猪对氨基酸和能量需求的分析

正1猪对氨基酸的需求氨基酸通过不同的组合连接在一起形成不同的蛋白质。构成蛋白质的氨基酸约有22种,猪能在体内合成其中的大多数,还有一部分则不能在体内合成,并且是正常健康和代谢过程所必需的,称之为必需氨基酸。猪的必需氨基酸包括:精氨酸、异亮氨酸、组氨酸、亮氨酸、赖氨酸、含硫氨基酸(蛋氨酸+胱氨酸)、芳香族(苯丙氨酸+酪氨酸)、苏氨酸、色氨酸、缬氨酸。     

玉米生物活性肽脱苦工艺技术研究

<正>一、脱苦工艺技术水解物中的疏水基多肽会带来蛋白质水解物的苦味,当人体的味蕾与含有较多疏水基团的多肽接触就会形成苦味。苦味与蛋白的水解度有着直接的关系,夏伦贝格尔理论认为是呈味分子的疏水基会导致苦味,通常蛋白质的疏水基被包裹在分子内部,加上蛋白质本身体积较大,因此疏水基没有机会接触到感受器,因此苦味没有被体现出来。然而,当经过水解作用将蛋白质分解成小分子活性肽时,疏水性氨基酸残基就会暴露出来,形成了苦味。因此,玉米蛋白水解物在食品中的     

插切矩形齿廓花键轴节圆半径的确定

用展成法加工各种共轭曲面具有诸多优点。齿廓为矩形的花键轴可用展成法加工。在加工时,如果工件节圆选得不当,就会产生顶切或其他问题。本文针对这一问题进行探讨。     

插切矩形齿廓花键轴节圆半径的确定

用展成法加工各种共轭曲面具有诸多优点，齿廓为矩形的花键轴可用展成法加工。在加工时，如果工件圆选得不当，就会产生顶切或其他问题，本文针对这一问题进行探讨。     

Chain initiation and control of protein synthesis

Analysis of the enzymatic mechanism of chain extension during protein synthesis and studies with N-formylmethionyl-sRNA suggest that chain initiation requires formylation of the amino group of the amino acid destined to start chain growth. The existence of a set of starting triplets coding for a special set of N-formylaminoacyl-sRNA's is postulated. These triplets might be ambiguous in the sense that they specify different amino acids, depending on whether they are at the beginning of or within a message. A number of starting triplets and their NH(2)-terminal amino acids are predicted from previously suggested ambiguities. The biochenmical, regulatory, and genetic implications of a formylation step controlling chain initiation are discussed.     

The E5 transforming gene of bovine papillomavirus encodes a small, hydrophobic polypeptide

Bovine papillomavirus (BPV-1) contains two independent transforming genes that have been mapped to the E5 and E6 open reading frames (ORF's). The E5 transforming protein was identified by means of an antiserum against a synthetic peptide corresponding to the 20 COOH-terminal amino acids of the E5 ORF. The E5 polypeptide is the smallest viral transforming protein yet characterized; it had an apparent size of 7 kilodaltons. The transforming polypeptide is encoded entirely within the second half of the E5 ORF and its predicted amino acid composition is very unusual; 68% of the amino acids are strongly hydrophobic and 34% are leucine. Cell fractionation studies localized this polypeptide predominantly to cellular membranes.     

橡胶树乳管HbPMP1基因的克隆与表达分析

过氧化物酶体膜蛋白PMP是ABC转运蛋白ABCD亚家族蛋白之一．存在于过氧化物酶体膜上。研究表明．拟南芥中的ABCD亚家族ABC转运蛋白AtABCD1主要通过参与部分物质运输进入过氧化物酶体．其中包括茉莉酸合成的前体OPDA。本研究通过RACE技术克隆了一个ABCD亚家族ABC转运蛋白基因HbPMP1．并进行表达分析。结果表明：HbPMP1全长4011bp．编码1337个氨基酸残基,其表达产物与拟南芥AtABCDl有较高的相似性（氨基酸一致性为78％）：该基因在伤害及外源茉莉酸诱导下呈上调表达．推测其可能参与内源茉莉酸合成相关物质时的运输．     

猪源新城疫病毒SP13株的F基因克隆及序列分析

采用RT-PCR方法对猪源新城疫病毒(NDV)SP13株的F基因进行了扩增与克隆,并测定出F基因的核苷酸全序列,推导出氨基酸序列.F基因全长为1662 bp,单一的开放阅读框,编码553个氨基酸的长肽,裂解位点的氨基酸序列为112G-R-Q-G-R-L117,与弱毒株在这一区域的序列(112G-R/K-Q-G/S-R-L117)相符;F蛋白有6个潜在的糖基化位点和13个Cys残基位点,其疏水构型有3个强疏水区.通过同源率、系统发育、致病性、疏水性和抗原性等比较分析的结果表明,SP13与LaSota、Clone 30株不但同源性达到99.9%,而且在致病性、疏水性和抗原性等方面也极为相似.     

Quality control mechanisms during translation

Translation uses the genetic information in messenger RNA (mRNA) to synthesize proteins. Transfer RNAs (tRNAs) are charged with an amino acid and brought to the ribosome, where they are paired with the corresponding trinucleotide codon in mRNA. The amino acid is attached to the nascent polypeptide and the ribosome moves on to the next codon. The cycle is then repeated to produce a full-length protein. Proofreading and editing processes are used throughout protein synthesis to ensure the faithful translation of genetic information. The maturation of tRNAs and mRNAs is monitored, as is the identity of amino acids attached to tRNAs. Accuracy is further enhanced during the selection of aminoacyl-tRNAs on the ribosome and their base pairing with mRNA. Recent studies have begun to reveal the molecular mechanisms underpinning quality control and go some way to explaining the phenomenal accuracy of translation first observed over three decades ago.     

Microtubule-associated protein MAP2 shares a microtubule binding motif with tau protein

The microtubule-associated protein MAP2 is a prominent large-sized component of purified brain microtubules that, like the 36- to 38-kilodalton tau proteins, bears antigenic determinants found in association with the neurofibrillary tangles of Alzheimer's disease. The complete sequence of mouse brain MAP2 was determined from a series of overlapping cloned complementary DNAs. The sequence of the carboxyl-terminal 185 amino acids is very similar (67 percent) to a corresponding region of tau protein, and includes a series of three imperfect repeats, each 18 amino acids long and separated by 13 or 14 amino acids. A subcloned fragment spanning the first two of the 18-amino acid repeats was expressed as a polypeptide by translation in vitro. This polypeptide copurified with microtubules through two successive cycles of polymerization and depolymerization, whereas a control polypeptide derived from the amino-terminal region of MAP2 completely failed to copurify. These data imply that the carboxyl-terminal domain containing the 18-amino acid repeats constitutes the microtubule binding site in MAP2. The occurrence of these repeats in tau protein suggests that these may be a general feature of microtubule binding proteins.     

对几种食物混合后蛋白质的氨基酸分的质疑

为了更正食物混合后蛋白质的氨基酸评分表中的数据错误。利用WHO／FAO提供的标准蛋白质中的氨基酸含量与各类食物中的同种氨基酸含量进行重新计算,并对原表中的数据进行比较和校对,提供正确的理论依据。结果标明原表中的数据、结论与实际有很大的出入。如谷类、豆类和奶粉的混合比例应为67％、22％、11％,谷类、豆类和奶粉的氨基分为44、69和83,混合后的第一限制性氨基酸是赖氨酸（而非苏氨酸）,其氨基酸分为75,第二限制性氨基酸为色氨酸,其氨基酸分为83。     

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

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.     

基于转录组信息的艾纳香牻牛儿基牻牛儿基焦磷酸合成酶基因(BbGGPS)的克隆及序列分析

采用RT-PCR和RACE(Rapid amplification of c DNA ends)技术,从艾纳香(Blumea balsamifera L·DC)的叶片中克隆到二萜化合物合成的关键酶牻牛儿基牻牛儿基焦磷酸合成酶(Bb GGPS)基因。结果显示:Bb GGPS基因的c DNA全长1475 bp,包含开放阅读框(ORF)1002 bp,编码334个氨基酸;亚细胞结构定位于叶绿体,既非膜蛋白也非分泌性蛋白。疏水性分析显示,Bb GGPS是亲水性蛋白。同源性比对结果显示,Bb GGPS蛋白与其他植物中GGPS蛋白具有高度的相似性。系统发育分析表明,所有序列被聚为5大类,Bb GGPS与菊科植物刺菜蓟聚(Cynara cardunculus var)为一类,表明与其亲缘关系最近。