鳖甲活性多肽的合成及对肝星状细胞增殖的抑制作用(英文)

探讨鳖甲活性多肽的固相合成及对肝星状细胞(HSC-T6)增殖的抑制作用。根据鳖甲活性多肽的序列结构,采用固相方法对多肽进行全合成,并用MALDI-TOFMS质谱对合成多肽进行分析鉴定;肝星状细胞(HSC-T6)培养至对数生长期后,加入不同浓度合成多肽作用肝星状细胞株HSC-T6,采用MTS法分析HSC-T6生长的抑制作用;使用AnnexinV-FITC/PI法检测HSC凋亡率。结果显示通过固相合成可以得到与原序列结构一致的鳖甲合成多肽;鳖甲合成多肽浓度依赖性地抑制肝星状细胞增殖,并能显著提高肝星状细胞早期凋亡率。因此,可以成功地合成鳖甲活性多肽,且对肝星状细胞增殖有明显的抑制作用。     

鳖甲抗肝纤维化活性多肽的固相合成

目的固相合成鳖甲抗肝纤维化活性多肽,为开发抗肝纤维化多肽药物提供结构明确的受试品。方法采用固相合成法,以Fmoc保护氨基酸和Wang树脂为原料,经1 氧 3 双二甲胺羧基苯骈三氮唑四氟化硼盐、N 甲基吗啡啉缩合,以20%哌啶的N,N 二甲基甲酰胺溶液进行脱保护,用三氟乙酸切割试剂将多肽粗品从Wang树脂上切割下来。结果经反相高效液相色谱分析纯化,可得纯度>98%的目的肽,经质谱鉴定其相对分子质量与理论值一致。结论该合成方法条件温和、副反应少,操作简便,纯化效率高,可用于大规模合成目的肽。     

脊髓肽MP1的固相合成工艺及其免疫活性的研究

目的：对脊髓肽MP1的固相合成工艺进行优化，并研究其免疫活性。方法：采用Fmoc法对脊髓肽MP1进行固相合成，利用反相高效液相、质谱和氨基酸分析的方法对其进行性质鉴定，并采用MTT法对其进行免疫活性检测。通过探索不同的缩合时间、氨基酸用量和切割条件对合成效率的影响，由此找出适宜的合成条件。结果：以DMF为反应溶剂、HBTU／HOBt为缩合剂、缩合时间50min和氨基酸过量两倍进行多肽MP1的合成，并采用配方为：TFA-水-EDT-TES（90：6：3：1）的切割剂进行常温切割3．5h，此条件下粗品纯度可达到83．20％。质谱分析的分子离子峰[M＋H]＋是681．4与脊髓肽MPl的理论分子量680．80基本一致，氨基酸分析结果表明：脊髓肽MPl的氨基酸残基的实测摩尔比与理论摩尔比基本一致。纯化后的MP1具有明显的促进ConA刺激脾淋巴细胞增殖的作用。结论：本实验建立的固相合成工艺条件可以成功地合成具有免疫活性的脊髓肽MP1。     

肽合成

药用多肽因其涉及范围广、药用活性高、生物利用性好、副作用少等优点正被越来越多的药学工作者列为将来药物发展的主要方向。目前多肽合成方面主要以液相合成为主,本文在查阅大量文献的基础上对肽合成过程中,氨基酸的保护、肽键缩合等常见的方法做了总结,希望为科研工作者对肽类药物开发提供参考。     

盐酸环丙沙星制备中哌嗪缩合的绿色合成

目的改进盐酸环丙沙星制备中的哌嗪缩合反应。方法根据绿色化学的特点和要求,对环丙沙星合成工艺进行优化,避免了哌嗪缩合反应过程中使用有机溶媒,实现了哌嗪缩合的水相合成。结果及结论后处理过程得到简化,保护了自然环境。     

抗胆碱药α-环戊基苯甲氧基烃胺类化合物的合成

本文报道了一系列α-环戊基苯甲氧基烃胺类抗胆碱化合物的合成。所用的原料。α-环戊基苯甲醇系由澳代环戊烷和苯甲腈进行格氏反应,得到的环戊基苯基酮,再以四氢铝锂还原成相应的醇。此法制备的较文献方法的产率高,且为纯品。以α-环戊基苯甲醇和氯代烃胺在氢化钠存在下缩合或以。α-环戊基-α-氯代苯甲烷与氮杂环烷醇缩合制得目的物。药理筛选结果显示,所合成的化合物都有不同程度的抗胆碱作用。     

维拉卡肽的固液相结合合成及其活性检测

目的 研究维拉卡肽固液相结合合成方法，并检测其钙敏受体激动活性。方法 选用Rink-Amide-AM氨基树脂，固相合成中采用HOBt/DIC缩合体系，液相形成二硫键采用TFA∶PhSMe∶H₂O∶TIS(V∶V)=91∶3∶3∶3条件裂解，经2,2′-二硫二吡啶活化后，偶联L-半胱氨酸。通过测试其钙敏受体激动活性来评估多肽活性。结果 合成粗肽经高效制备色谱纯化与RP-HPLC分析，纯度为99.9%(HPLC法，220 nm),合成收率为79.5%。目标化合物对钙敏受体激动活性的EC₅₀=12.75μmol·L^-1,与文献报道相当。结论 该合成方法优化了二硫键形成条件，适合工业化生产。     

Fmoc 策略固相合成磷酰化肽研究进展

蛋白质的磷酰化和去磷酰化对多种生命活动的调节起着关键的作用,磷酰化肽是研究这些生命调节过程中一类非常重要的物质。自 20 世纪 40 年代人类首次成功地合成出磷酰化肽以来,磷酰化肽的研究就引起了化学家和生物学家的广泛关注。由于Fmoc 固相合成策略在多肽的合成中被普遍应用,因此,Fmoc 固相合成策略也已经成为目前磷酰化肽最主要的合成手段。该文对近年来采用 Fmoc 固相合成策略进行磷酰化肽合成的方法（包括整体磷酰化法和磷酰化单体合成法）进行了总结,并对各种合成方法的优缺点进行了讨论。     

试论外科"双师型"教师的培养

通过对我省卫生职业学校（院）中外科“双师型”师资的现状调查，发现“双师型”外科教师严重匮乏且培养起来比较困难，鉴于“双师型”外科教师在培养“技能型”、“临床思维型”卫生技术人才中的重要性，提出了建立健全“双师型”教师培养激励机制、发展附属医院和院校合作等途径来培养“双师型”外科教师的具体措施。     

固相法在多肽合成领域的应用

综述近年来固相多肽合成方法在聚合物载体、连接分子、保护基、缩合方法和切割条件等方面的应用进展。多肽的全合成不仅具有重要的理论意义，而且具有重要的应用价值。特别是固相多肽合成方法的创立和发展，是多肽合成领域的一个重大突破，对化学、生化、医药、免疫及分子微生物学等领域都起了巨大的推动作用。     

Application of triazine "superactive esters" in the repetitive synthesis of oligopeptides. Part 2. Synthesis of N-terminal hexapeptide of emerimicin III

N-terminal fragment of emerimicin III has been synthesized by the repetitive method in solution, involving triazine ,,superactive esters". The synthetic protocol, equivalent to the classic REMA procedure, has been applied in the step by step approach, and in the fragment coupling affording all the peptide bonds. By monitoring the progress of the synthesis by FAB-MS, 1H-NMR and HPLC, the structure and high purity of the final products have been confirmed.     

Application of carboxylic-phosphinic mixed anhydrides in the fragment peptide synthesis of protected analogues of substance P

Mixed carboxylic-phosphinic anhydrides derived from peptide acids and 1-oxo-1-chlorophospholane have been applied in the synthesis of the protected [Leu¹¹]-SP_1-11 by the fragment coupling strategy. The yields from fragment couplings were ca. 75%, the products were of high purity while the conditions of formation and coupling of the corresponding mixed phosphinic anhydrides, for optimum yields, have been evaluated.     

Solid-phase peptide synthesis using tert.-butyloxycarbonylamino acid pentafluorophenyl esters

Boc-amino acid pentafluorophenyl esters have been successfully used in solid-phase peptide synthesis. The coupling rates and the purity of the products are comparable to those with the symmetrical anhydrides. These active esters require modified Merrifield resin, polar medium for coupling and in some cases, base catalysis.     

Targeting "hydrolytic" activity of the S-adenosyl-L-homocysteine hydrolase

Substrates that are specific for the "hydrolytic" activities of AdoHcy hydrolase have been recently identified. Upon interaction with the AdoHcy hydrolase such substrates generate the "active" electrophiles which then react with the enzyme nucleophiles to produce covalent inhibition. Dihalohomovinyl and haloacetylene analogues derived from adenosine as well 5'-S-allenyl-5'--thioadenosine derivative have been characterized as the first type II mechanism-based inhibitors of AdoHcy hydrolase that rely only on the "hydrolytic" activity. Design and synthesis of the novel adenine nucleosides as well their interaction with AdoHcy hydrolase are discussed in this review.     

Incorporation of azaglutamine residues into peptides synthesised by the ultra-high load solid (gel)-phase technique

The solid (gel)-phase peptide synthesis of peptides, each containing an azaglutamine residue, has been examined. Procedures using various mono-, di- and tripeptide and carbazate fragments containing or relating to an azaglutamine (1) residue have been evaluated. N-Activation of the amino-terminus of a resin-bound peptide with bis-(2,4-dinitrophenyl)carbonate (2) yielded the terminal isocyanate species, which reacted with protected carbazates to give resin-bound protected peptides containing the aza-residue. By contrast, coupling of activated amino-acid derivates to the free amino-group of a resin-bound peptide with an aza-residue at the N-terminus was a slow and unsatisfactory process. It is concluded that the route yielding the best results involves the reaction of a protected amino-acyl carbazate to a resin-bound isocyanate-activated peptide.     

Multiple peptide synthesis using a single support (MPS3)

An automated multiple peptide synthesis method to synthesize, cleave, and purify several peptides simultaneously in a single batch has been developed. The technique is based on the synthesis of multiple peptides on a single solid phase support and is easily adapted to manual or to automated methods. The approach relies on coupling of amino acid mixtures to the resin and it has been found that DCC/HOBt gives the best coupling performance. Fast Atom Bombardment Mass Spectrometry (FAB-MS) was used to rapidly and efficiently identify the peptides in each synthetic mixture which significantly assisted the purification process by HPLC. The method has been successfully applied to the synthesis of magainin 2 and angiotensinogen peptides.     

Incomplete Fmoc deprotection in solid-phase synthesis of peptides

During solid-phase peptide synthesis of homo-oligopeptides containing leucine or alanine using the Fmoc strategy, we have observed ineffective N-α-deprotection with piperidine in a sequence-dependent manner. Incomplete deprotection was found to be associated with subsequent slow or incomplete amino acid coupling. Optimization of the deprotection step was carried out by varying the experimental conditions e.g. deprotection time, temperature, solvents and addition of chaotropes. Coupling and deprotection steps have been investigated using color monitoring, as well as FAB MS and HPLC for product analysis. The phenomena of difficult coupling and deprotection steps in the investigated systems have been demonstrated to have the same physical chemical origins, p-sheet formation. © Munksgaard 1994.     

Role of the signal peptide in the synthesis and processing of the glucagon-like peptide-1 receptor

Background and purpose:

The glucagon-like peptide-1 receptor (GLP-1R) belongs to Family B of the G protein-coupled receptor superfamily and is a target for treatment of type 2 diabetes. Family B G protein-coupled receptors contain a putative N-terminal signal peptide, but its role in receptor synthesis and trafficking are unclear. Further, the signal peptide is not cleaved in at least one family member.

Experimental approach:

We examined receptor glycosylation and the role of the signal peptide in GLP-1R synthesis and trafficking using constructs containing epitope tags at the N- and/or C-terminus and in which the signal peptide sequence was either present or absent.

Key results:

The signal peptide was absolutely required for GLP-1R synthesis but could be substituted to some extent by increasing positive charge in the N-terminal region of the receptor flanking the signal peptide. The signal peptide is cleaved during synthesis and processing of the receptor. An enhanced GFP-epitope tag at the N-terminus of the receptor permitted synthesis of the receptor but blocked signal peptide cleavage and prevented trafficking to the plasma membrane. Cleavage site mutation allowed synthesis of a full-length receptor, blocked signal peptide cleavage and caused retention within the endoplasmic reticulum.

Conclusions and implications:

Signal peptide cleavage was not essential for receptor synthesis but was obligatory for processing and trafficking of receptors to the plasma membrane. Further, the GLP-1R is subject to N-linked glycosylation and only the mature, fully glycosylated form of the receptor is present in the plasma membrane. Inhibition of glycosylation prevents processing and cell surface expression of the GLP-1R.     

Use of Mpc-amino acids in solid phase peptide synthesis leads to improved coupling efficiencies

The Mpc-group has a somewhat better stability than the Fmoc-group, resists catalytic hydrogenolysis, is highly stable in acidic media and its elimination product does not polymerize spontaneously. In a direct comparison of coupling efficiencies obtained in solid phase peptide syntheses using Mpc- or Fmoc-amino acids it is shown that the use of Mpc-amino acids leads to better coupling efficiencies and, consequently, a more homogeneous peptide. An improved synthesis of Mpc-ONSu and of Mpc-amino acid derivatives is presented.