细胞粘附肽Arg-Gly-Asp的合成与生物活性检测

采用固相多肽合成法合成Ag-Gly-Asp(RGD)三肽,以天门冬氨酸计RGD三肽收率为75%,采用MTT法进行合成肽RGD抑制人纤维肉瘤细胞HT1080转移机理方面的研究,证实了人工合成的RGD肽能抑制人纤维肉瘤细胞HT1080与纤维连接蛋白(FN)的粘附.     

抗HIV-1gp41合成多肽gp41-5单克隆抗体的制备及初步鉴定

制备抗HIV-1 gp41合成多肽gp41-5的单克隆抗体（mAb）,为筛选抗HIV-1多肽及分析gp41的抗原表位提供有用工具。常规动物免疫、细胞融合、克隆化制备抗gp41-5多肽mAb,并用ELISA法对其特异性、抗原识别表位及相对亲和力等做了初步鉴定。获得了4株抗gp41-5多肽的mAb,这4株mAb均特异识别gp41-5多肽,但不与gp41的N36或C34多肽片段反应。得到的4株mAb能特异结合gp41核心结构的空间构象。     

花生种子贮藏蛋白发育和萌发过程中17.5×103多肽的合成降解规律

目的 :分析花生球蛋白、伴花生球蛋白Ⅰ和伴花生球蛋白Ⅱ及其组成多肽的氨基酸组成 ,筛选高甲硫氨酸多肽并研究其在花生种子发育和萌发过程中的合成降解规律 方法 :花生球蛋白、伴花生球蛋白Ⅰ和Ⅱ经SephadexG - 10 0纯化后 ,再以制备电泳和电泳洗脱得到高纯度的 5种多肽 ;酸水解法测定了花生球蛋白、伴花生球蛋白Ⅰ和Ⅱ以及 5种多肽的氨基酸组成 ;WesternBlot分析了种子发育和萌发过程中 17 5× 10 3多肽的合成降解规律 结果 :花生球蛋白、伴花生球蛋白Ⅰ和Ⅱ以及 5种多肽均含有 17种氨基酸 (包括 8种必需氨基酸 ) ,其中天冬氨酸、谷氨酸和精氨酸含量为最高 ,约为总量的 4 5% ;而甲硫氨酸含量水平都极低 在这 5种多肽中 ,17 5× 10 3多肽的甲硫氨酸含量最高 17 5× 10 3多肽在花生种子发育早期开始合成 ,而在种子吸涨 60h时发生降解 结论 :17 5× 10 3多肽的甲硫氨酸含量最高 ,在花生种子发育和萌发过程中它的合成降解规律与花生球蛋白和伴花生球蛋白Ⅰ不同     

内吗啡肽-2的合成研究

用液相多肽合成法合成具有镇痛作用的μ阿片受体的内源性配体———内吗啡肽-2.直接使用叔丁氧羰基保护的有关氨基酸,采用DCC/HOB t缩合法和混合酸酐法分别合成N-端二肽片段和C-端二肽片段,然后将N-端二肽片段和C-端二肽片段缩合成四肽,最后用50%的TFA/DCM脱除保护基,成功地合成了内吗啡肽-2.本实验方法与文献相比,步骤减少,后处理简便,收率提高.     

甘丙肽受体新配基的合成

基于目标化合物的结构和液相肽片段合成方法的优点,设计采用液相合成方法,以混合酸酐法使羧基和氨基缩合,经缩合、脱除Fmoc保护基、缩合、脱除Boc保护基4步反应,共合成了5个中间体和3个新甘丙肽受体新配基,目标化学物和部分中间体的结构经1H NMR或MS确证.所有反应均在温和条件下进行,操作简便,收率较高.     

细胞粘附肽Arg-Gly-Asp的合成与生物活性检测

采用固相多肽合成法合成Ag-G ly-Asp(RGD)三肽,以天门冬氨酸计RGD三肽收率为75%,采用MTT法进行合成肽RGD抑制人纤维肉瘤细胞HT1080转移机理方面的研究,证实了人工合成的RGD肽能抑制人纤维肉瘤细胞HT1080与纤维连接蛋白(FN)的粘附。     

碳末端修饰的内吗啡肽类似物的合成和活性测定

本文采用片段缩合的液相多肽合成方法合成了内吗啡肽母体及其类似物共8个化合物,通过质谱鉴定其分子量,通过豚鼠回肠纵行肌实验（GPI）和小鼠输精管实验（MVD）鉴定它们的离体活性,结果表明内吗啡肽碳末端为中性或弱碱性有利于内吗啡肽跟μ阿片受体的结合,不利于跟δ阿片受体的结合;芳环朝向能大大影响其受体亲和性和选择性。     

化学-酶法合成RGD三肽

采用化学法和酶法相结合的合成策略,合成具有高生物活性肽RGD.先采用DCC合成GD二肽(HCl*Gly-Asp(oBzl)2),然后利用胰蛋白酶(trypsin)催化合成 RGD三肽(Z-Arg-Gly Asp(oBzl)2).实验结果表明,其中GD二肽在反应10 h,两底物G与D的摩尔比为1.5∶1时,得率为77.7%;RGD三肽在微水-1,4-丁二醇反应体系中得率为41.9%.     

甲烷磺酸N-羟基琥珀酰亚胺酯的制备及其在寡肽合成中的应用

制备甲烷磺酸N-羟基琥珀酰亚胺酯,并将其应用于寡肽的液相合成.以N-羟基琥珀酰亚胺与甲烷磺酰氯反应制备甲烷磺酸N-羟基琥珀酰亚胺酯,并使其与Boc保护的酪氨酸、丙氨酸或Boc保护的酪氨酰脯氨酸发生SN2取代反应,生成相应的N-羟基琥珀酰亚胺活泼酯而活化羧基,并成功用于内吗啡肽-2和力肽的液相合成;N-羟基琥珀酰亚胺活泼酯的制备和应用反应条件温和、副产物少、收率较高.实验结果表明,甲烷磺酸N-羟基琥珀酰亚胺酯可用于寡肽的液相合成.     

乙酰乙酰氨基酸合成方法的改进

由氨基酸合成蛋白质或多肽时,使它的氨基与苄氧羰基或乙酰乙酰基等结合,作为保护基团,使它的羧基成为单一转化中心,反应完成后,可通过还原等方法将保护基除去.制备乙酰乙酰氨基酸的方法过去主要采用氨基酸的水溶液,在等当量的氢氧化钠存在下,与双烯酮(diketene)在0℃左右的低温下进行反应:     

机械振荡对多态四膜虫胞口分化中多肽合成的影响

通过对~(35)S~-甲硫氨酸标记细胞的双向电泳表明,多态四膜虫Tetrahymena vorax小胞口细胞转化为大胞口细胞后,合成了大胞口特异类型的多肽。而且,机械振荡对于胞口类型分化的影响,也在于影响这些大胞口细胞形成所需的多肽。     

Production of multiple plant hormones from a single polyprotein precursor.

Some animal and yeast hormone genes produce prohormone polypeptides that are proteolytically processed to produce multiple copies of hormones with the same or different functions. In plants, four polypeptides have been identified that can be classed as hormones (intercellular chemical messengers) but none are known to be produced as multiple copies from a single precursor. Here we describe a polyprotein hormone precursor, present in tobacco plants, that gives rise to two polypeptide hormones, as often found in animals and yeast. The tobacco polypeptides activate the synthesis of defensive proteinase-inhibitor proteins in a manner similar to that of systemin, an 18-amino-acid polypeptide found in tomato plants. The two tobacco polypeptides are derived from each end of a 165-amino-acid precursor that bears no homology to tomato prosystemin. The data show that structurally diverse polypeptide hormones in different plant species can serve similar signalling roles, a condition not found in animals or yeast.     

光对小麦幼苗poly(A)mRNA及其体外翻译产物的影响

用亲和层析、体外翻译、~3H-亮氨酸参入和放射自显影研究了光对小麦幼苗叶内RNA、poly(A)mRNA和体外翻译产物的影响。光引起小麦幼苗叶内ENA和mRNA含量提高,SDS-PAGE表明体外的翻译产物也有变化、主要表现在照光后29～32KD前体蛋白出现并增多;77.6、73、67、47.3、20、17KD多肽也增加,而121.4、15.8KD蛋白减少。光影响了小麦叶基因的表达。     

诸葛菜花粉不同发育时期特异性蛋白多肽研究

对诸葛菜(Orychophagmus violaceus)花粉不同发育时期蛋白多肽进行双向电泳，结果发现花粉发育的3个时期出现蛋白多肽点的数量为：单核期121个，二核期192个，三核期275个,3个时期共有(指等电点和分子量相同)的蛋白多肽点有100个．各时期特有的蛋白多肽点分别为：单核期9个，二核期15个，三核期110个。三核期蛋白多肽点数量和特有蛋白多肽点数量的大量增加，说明诸葛菜花粉发育晚期蛋白表达异常活跃，为受精提供了物质上的准备，同时还发现不同发育时期的花粉，其相应蛋白多肽的含量有增有减。     

Nanoengineered polypeptides from tetraphenylethylene-functionalized N-carboxyanhydride: Synthesis,self-assembly and intrinsic aggregation-induced emission

Ring-opening polymerization of N-carboxyanhydrides (NCAs) bearing pendant groups creates functional polypeptides. In this paper, we report the design, synthesis and polymerization of tetraphenylethylene (TPE)-modified NCA, which is used to incorporate aggregation-induced emission (AIE)-active segments into polypeptides. Specifically, we attempted the synthesis of amphiphilic methoxy poly(ethyleneglycol)-block-poly(γ-benzyl-_l-glutamate)-block-poly(γ-4-(1,2,2-triphenylvinyl)benzyl-_l-glutamate) (PEG-PBLG-PTPELG), which had well-controlled molecular weight and narrow polydispersity. The hydrophilic PEG and hydrophobic PBLG-PTPELG assembled into micelles in aqueous solution with diameter around 70 ​nm, displaying AIE at 480 ​nm. Our work demonstrates that the TPE-modified NCA is applicable for the preparation of the AIE-active polypeptides, integrating the AIE luminogens into the polypeptides which may offer unique opportunities for tuning AIE properties by adjusting the composition and conformation of polypeptides. We preliminarily explored the use of the amphiphilic polypeptides for the formulation of doxorubicin-containing micelles that can potentially be used for real-time monitoring of the nanomedicine distribution.     

Evidence for the formation of heteromultimeric potassium channels in Xenopus oocytes

Potassium channels show a wide range of functional diversity. Nerve cells typically express a number of K+ channels that differ in their kinetics, single-channel conductance, pharmacology, and sensitivity to voltage and second messengers. The cloning of the Shaker gene in Drosophila, and of related genes, has revealed that the encoded K+ channel polypeptides resemble one of the four internally homologous domains of the alpha-subunits of Na+ channels and Ca2+ channels, indicating that K+ channels may form by the co-assembly of several polypeptides. In this report we provide evidence that the Shaker A-type K+ channels expressed in Xenopus oocytes contain several Shaker polypeptides, that heteromultimeric channels may form through assembly of different channel polypeptides, that the kinetics or pharmacology of some heteromultimeric channels differ from those of homomultimeric channels, and that channel polypeptides from the fruit fly can co-assemble with homologous polypeptides from the rat. We suggest that heteromultimer formation may increase K+ channel diversity beyond even the level expected from the large number of K+ channel genes and alternative splicing products.     

超高压辅助酶法脱除黄曲霉毒素B1工艺对米糠多肽品质的影响

研究了超高压辅助酶法脱除黄曲霉毒素B₁优化工艺对米糠多肽品质的影响。研究表明,在超高压300MPa条件下,随着超高压处理时间(0、1、3、5、7、9min)的延长,超高压辅助酶法制备无毒米糠多肽的多肽得率、水解度、溶解性、起泡稳定性、乳化性和乳化稳定性先提高后下降,起泡性和持油性显著提高,而持水性呈下降趋势。因此,该工艺不仅能确保米糠多肽产品安全无毒,还可提高米糠多肽的品质。     

植物胞外多肽与人细胞因子的结构特征比较

植物细胞外多肽信使已经被证实是植物信号转导中重要的第一信使,运用生物信息学的方法,分析比较了已知的植物胞外多肽和人的细胞因子的氨基酸序列,发现这些来自不同界别的胞外多肽具有某些共同的结构特征,利用在线工具对胞外多肽的结构特征进行了验证,并根据细胞外多肽的结构特征推测了钙调素受体的三维结构,这些结果对发现新的植物胞外多肽及推测其可能的受体有重要意义.     

大豆ASR蛋白富含组氨酸结构域在结合金属离子中的作用

利用固相亲和层析实验结果表明,GmASR蛋白及其含组氨酸结构域A1~A5短肽可与金属离子Cu2+和Cd2+结合；采用Cu-抗坏血酸体系检测了GmASR蛋白及A1~A5清除羟基自由基的能力，证明GmASR蛋白及A1~A5短肽中组氨酸数目与清除羟基自由基能力呈正相关；GmASR蛋白及A1~A5可保护DNA分子免受Cu2+造成的氧化损伤.CD实验和SDS-PAGE实验结果发现，GmASR蛋白及A1~A5短肽与Cu2+结合后将引起可逆性聚集及沉淀.可见GmASR蛋白通过组氨酸结合过多的金属离子，维持细胞内离子平衡，是保护植物免受重金属毒害的重要机制之一.     

H-2-linked low-molecular weight polypeptide antigens assemble into an unusual macromolecular complex

The major histocompatibility complex (MHC) is a cluster of tightly linked genes whose products are of central importance in the functioning of the immune system. Class I and II MHC antigens are integral membrane proteins which regulate cell-surface interactions between T cells and their targets, while class III antigens are components of the complement system of serum proteins. All available evidence indicates that the structure and function of the MHC and its gene products are highly conserved among species (for review, see ref.5). We recently reported the existence in murine cells of a fourth class of MHC-linked polypeptides which are biochemically and genetically distinct from previously identified MHC gene products: BALB.B anti-BALB/c (anti-H-2d) antiserum immunoprecipitates a set of 16 cytoplasmic low-molecular weight polypeptides (LMP) from BALB/c spleen cells and from the WEHI-3 cell line. The production of these peptides is coordinately regulated (by immune interferon) with the production of the class I and II MHC antigens, suggesting that they too are functionally relevant to the immune system. We demonstrate here that these 16 polypeptides are associated with one another in vivo as a very large (580,000-molecular weight, Mr) noncovalent complex. The unusual nature of this complex has allowed the non-immunochemical identification of similar complexes from (serologically negative) H-2b murine cells and from a human cell line. Thus, LMP antigens display two properties in common with other MHC antigens: they are both polymorphic and genetically conserved across species.