利用基质抑制效应检测小质量的气溶胶粒子

研究了气溶胶粒子的基质辅助激光解吸附电离质谱，在基质对分析物的摩尔比较高时，同时出现了基质和分析物离子峰；在基质对分析物的摩尔比低于5：1时，出现了基质抑制效应。基质抑制效应可以产生高质量的质谱，即：质谱中分析物信号较强，基质信号很弱或者消失。因此，利用基质抑制效应，可以检测低分子量的分析物。     

壳聚糖的基质辅助激光解吸电离飞行时间质谱分析

利用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)分析甲壳素脱乙酰化降解产物——壳聚糖,对基质、制样方法等影响MALDI-TOF-MS测定结果的因素进行了研究。实验发现,以2,5-二羟基苯甲酸(DHB)为基质,二次结晶法制样分析壳聚糖,既获得了壳聚糖的分子量信息,又可以推断壳聚糖的脱乙酰度,对壳聚糖的制备及其质量与性能控制有着十分重要的指导意义。     

磁性颗粒在基质辅助激光解吸电离飞行时间质谱分析多肽类物质中的应用北大核心CSCD

制备了由SmFeN磁性颗粒(MPs)和芥子酸(SA)组成的复合基质,并应用于基质辅助激光解吸电离飞行时间质谱法(MALDI-TOF-MS)分析典型的低分子多肽类物质,使分析物相关的质谱峰明显增强。试验确定复合基质中SA和MPs的质量比的最佳值为4∶0.5,此时,[Sub P+Na]^+的信号强度增加了约40倍。同时,采用紫外-可见漫反射光谱法对复合基质的工作机理作了初步探讨。     

激光解吸电离质谱新型液相基质研究

选用包括纳米粒子在内的多种基质化合物,构成了多种不同组成的液相基质.以多肽、蛋白、大环寡糖和有机小分子等数种类型化合物为样品,系统地考察了不同液相基质在基质辅助激光解吸电离飞行时间质谱(MALDI-TOF)分析中的应用情况,探讨了与固体制样方法的异同点.实验结果表明,有些液相基质对多类化合物具有较好的通用性,而有些液相基质对某些特定类型化合物的分析特别有效.     

用基质辅助激光解吸电离飞行时间质谱法测定钙调蛋白的纯度与分子量

采用基质辅助激光解吸电离飞行时间质谱法测定了钙调蛋白的纯度与分子量,并对所得的结果进行了讨论,实验结果表明本方法具有灵敏度高,分析速度快,重复性好,信息直观等特点,是其他传统测定蛋白质分子量的方法无法比拟的。     

香豆素类新基质用于基质辅助激光解吸／电离飞行时间质谱对聚乙二醇的测定

首次以6种香豆素衍生物--3-氨基香豆素(3-AC)、3-羟基香豆素(3-HC)、3-羧基香豆素(3-CC)、4-甲基-7-羟基香豆素(4-M-7-HC)、3-乙酰氨基香豆素(3-AcAC)和3-苯基-7-乙酰氨基香豆素(3-ph-7-AcAC)为基质对聚乙二醇样品进行基质辅助激光解吸/电离飞行时间质谱(MALDI TOF-MS)分析.结果表明:3-AC、3-HC和3-CC均能有效解吸电离聚乙二醇样品,产生分辨率高、离子信号强、信噪比高的质谱图,不仅测定了聚乙二醇样品的数均相对分子质量、重均相对分子质量和聚合度分布,还能够准确地推测出样品的端基结构和重复单元,将为改善高分子合成反应条件和机理推导提供确凿依据.3-AC、3-HC和3-CC香豆素衍生物将为MALDI TOF-MS分析高分子聚合物提供新的基质选择.     

蛋白质组学中基质辅助激光解吸电离的基质研究进展

基质辅助激光解吸电离(MALDI)技术是近年来发展起来的新的质谱离子化技术。本文较为系统地综述了应用于蛋白质组学中的MALDI基质的最新进展以及不同的基质的优缺点及应用范围,并且归纳了其发展趋势。     

应用基质辅助激光解吸电离飞行时间质谱法测定牛甲状腺球蛋白的分子量

应用基质辅助激光解吸电离飞行时间质谱法测定了牛甲状腺球蛋白的纯度与相对分子量.选择芥子酸为适宜的基质,并对所得的结果进行了讨论.实验结果表明分析方法具有灵敏度高、重现性好、信息直观等特点,明显优于其他传统测定蛋白质的方法.     

一系列阳离子性卟啉化合物的基质辅助激光解吸质谱行为

应用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)研究了一系列阳离子性卟啉化合物的质谱行为.结果表明,阳离子性卟啉与非离子性卟啉化合物的激光解吸电离方式有明显不同.对于四-氮R基(R=甲基,乙基,丙基,苄基)吡啶基卟啉,吡啶基氮上的侧链基团(R)可明显影响该类化合物在MALDI-TOF-MS测试过程中离子形成方式;R基团的增大以及平衡阴离子半径的增大可增加平衡阴离子与卟啉环阳离子之间相互作用力的共价成分,因此在MALDI-TOF-MS测定过程中能够得到卟啉环阳离子与多个平衡阴离子结合在一起的较高质量数的离子峰.另外,还初步探讨了阳离子性卟啉化合物的激光解吸电离机理.     

Biotinylation of Peptides/Proteins Using Biocytin Hydrazide

Biocytin hydrazide is widely used to biotinylate the carbohydrate moieties of glycoproteins. In this study, however, biocytin hydrazide was found to be able to directly biotinylate peptides and proteins. This phenomenon may cause false identification of non‐glycopeptides/non‐glycoproteins as glycopeptides/glycoproteins. Here, we report a systematic investigation of the reaction of peptides/proteins with biocytin hydrazide. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry is used to analyze the biotinylation reaction between peptides/proteins and biocytin hydrazide. Peptides/proteins were reacted with biocytin hydrazide in diverse solvent systems with different biocytin hydrazide concentrations for up to 96 h at temperatures ranging from 4 °C to 65 °C. Singly biotinylated or multiply biotinylated peptides/proteins are observed. The efficiency of the biotinylation reaction increases with higher temperature, higher biocytin hydrazide concentration, or longer reaction time. The influence of buffer pH on the biotinylation reaction of peptides/proteins is less pronounced. The biotinylation efficiency is optimum at neutral pH. Data suggests that the peptides are biotinylated as efficiently as proteins. The observation that peptides/proteins condense only with biocytin hydrazide, 2‐iminobiotin hydrazide, adipic dihydrazide and phenyl hydrazine but not with biocytin HCl and 2‐iminobiotin, indicates that the biotinylation reaction of peptides/proteins occurs with the hydrazide moiety but not with biotin moiety of the biotinylated reagent. The postsource decay data of biotinylated P₁₄R indicates that biocytin hydrazide condenses with the guanidino group of arginine's side chain of P₁₄R, indicating that besides N‐terminal and lysine residue of peptides/proteins, arginine residue is capable of reacting with biocytin hydrazide.     

Preparation and Anti-oxidative Effects of Corn Peptides

IntroductionBioactive peptides include the natural peptidesfrom organism itself and the active peptide fromhydrolysate of protein. In the pastfew years,someresearchers have found that small peptides derivedfrom the hydrolysates of food proteins play animportant role in regulating autonomic nervoussystem,activating the cellular immunity function,ameliorating the cardiovascular function,antioxidizing and antiaging,etc.[1— 7] . Smallpeptides prepared from food proteins becomenitrogenous source f…     

Applications of Synthetic Peptides

Peptide chemists are increasingly concerned with the synthesis of polypeptides of biological and medical interest. This article describes several important applications of synthetic peptides in biochemistry, molecular biology, immunology, and medicine. Synthetic peptides may be useful in structure-function studies of polypeptides, as peptide hormones and hormone analogues, in the preparation of cross-reacting antibodies, and in the design of novel enzymes. Peptide chemists can actively contribute to progress in these fields if they are aware of the current problems in the life sciences.     

蛋白质、多肽类药物控制释放体系的研究

近年来,蛋白质、多肽类药物广泛应用于各类疾病的治疗。本文对聚乙二醇修饰的蛋白质及蛋白质类药物控制释放这两大体系的研究进展做了较系统的总结和评述,并就更高级的靶向、易吸收的蛋白质药物体系的发展进行了展望。     

Does in-source decay occur independent of the ionization process in matrix-assisted laser desorption?

The influence of the acidic and basic characters of constituent amino acid residues on the peptide fragment ions produced by in-source decay under matrix assisted laser desorption/ionization (MALDI) conditions has been studied using positive- and negative-ion experiments. Whereas the in-source decay spectra of peptides containing basic Arg and/or Lys residues near the N-terminus showed so-called c_n- and a_n-series ions in positive-ion mode, a peptide that has an acidic amino acid cluster near the N-terminus and a basic residue near the C-terminus characteristically formed y_n- and z_n-series ions in the positive-ion in-source decay spectrum. These results indicated that fragment ion series produced by in-source decay depend strongly upon the acidic and basic characters of the constituent amino acid residues and the near N- and C-termini. It was suggested that in-source decay processes occur intrinsically at NH–C^α and CO–NH bonds independent of the formation of molecular-related ions, and that the cleavages at the NH–C^α and CO–NH bonds occurred independently and were dependent on the matrix used.     

Conformational Requirements for Sweet-Tasting Peptides and Peptidomimetics

The molecular basis o taste has been extensively studied over many years. The research carried out in our laboratories is focused on the elucidation of detailed structure–taste relationships of peptides and peptidomimetics using an “integrated” approach employing synthesis, analysis of NMR spectra, computer simulations, and X-ray crystallography. Various peptidomimetic residues have been incorporated to introduce predictable structural constraints into taste ligands. These constraints eliminate some of the molecular flexibility and allow us to develop structure–activity relationships. We describe here the topochemical requirements of the sweet and bitter taste receptor(s) and develop detailed structure-taste relationships with considerable predictive power for peptides and related molecules.     

Electrochemical Nickel-Catalyzed Selective Inter- and Intramolecular Arylations of Cysteine-Containing Peptides**

Here we report a simple electrochemical route towards the synthesis of S-arylated peptides by a site selective coupling of peptides with aryl halides under base free conditions. This approach demonstrates the power of electrochemistry to access both highly complex peptide conjugates and cyclic peptides.     

多肽的快原子轰击质谱／质谱研究

通过快原子轰击质谱（ＦＡＢＭＳ）可确定多肽的分子量，而在此基础上采用活化碰撞（ＣＡ）技术可对氨基酸的序列进行识别。     

Construction of Thioamide Peptides from Chiral Amino Acids

Thioamide peptides were synthesized in a straightforward one-pot process via the linkage of diverse natural amino acids in the presence of thiolphosphonate and trichlorosilane, wherein carbonyl groups were replaced with thiono compounds with minimal racemization. Experimental and computational mechanistic studies demonstrated that the trichlorosilane enables the activation of carboxylic acids via intense interactions with the Si−O bond, followed by coupling of the carboxylic acids with thiolphosphonate to obtain the key intermediate S-acyl dithiophosphate. Silyl-activated quadrangular metathesis transition states afforded the thioamide peptides. The potential applications of these thioamide peptides were further highlighted via late-stage linkages of diverse natural products and pharmaceutical drugs and the thioamide moiety.     

功能多肽在肿瘤治疗中的应用及研究进展

多肽具有生物相容性好,功能多样化,生物体内响应性高及合成修饰方法简单易行等优点,已被广泛用于构建靶向药物传递系统。以具有靶向功能和刺激响应性的多肽为基础构建的药物传递系统,能够将药物定向地运送到肿瘤区域。药物传递系统到达肿瘤组织后,在肿瘤组织特殊微环境或外源刺激下,实现药物的精准释放。这种具有特异性肿瘤靶向和刺激响应型的多肽载体可以最大程度地提高药物的抗肿瘤效果,降低药物的毒副作用。本文简要介绍了常用的靶向多肽和刺激响应型多肽,并讨论了基于功能型多肽的药物载体在肿瘤治疗方面的应用。