半乳糖修饰人血清白蛋白的质谱分析

研究发现,存在于哺乳动物肝细胞膜上的血浆无唾液酸糖蛋白受体(asialoglycoproteinreceptor,ASGP-R)是一种肝结合蛋白(hepaticbindingprotein,HBP),能专一性识别分子末端带有半乳糖残基的糖蛋白并与之结合,定向转到肝细胞内的溶酶体进行代谢,针对ASGP-R作为靶点的肝靶向药物载体半乳糖化人血白蛋白偶合物(galactosyl-neoglycoalbumin,NGA),已引起药物研究工作者的极大重视。将药物与带有半乳糖残基的蛋白偶合,可提高药物的肝靶向性,提高治疗指数,减少非靶器官的毒副作用。大量研究表明,肝结合蛋白受体介导的肝靶向给药系统是最具研究价值和应用前景的肝靶向给药系统之一。     

Molecular structure investigations on fluorine containing polyazomethines by means of the MALDI-TOF-MS technique

Three new aromatic polyazomethines have been synthesized by solution polycondensation reactions of terephthalic dialdehyde with fluorine containing aromatic diamines. The polymers were obtained in high yields. The investigation of these polymers by means of matrix-assisted laser desorption ionization-time-of-flight-mass spectrometry (MALDI-TOF-MS) proved the initial members of the four theoretical possible series of the corresponding oligomers with 2-10 repeating units per molecule.     

基质辅助激光解析飞行时间质谱快速测定水解胶原蛋白粉分子量

应用基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MS)快速测定了水解胶原蛋白粉的分子量.分别以α-氰基-4-羟基内桂酸、2,5-二羟基苯甲酸和芥子酸为基质,在正离子模式下对水解胶原蛋白粉分子质量分布进行测定.结果显示:芥子酸为最适宜基质,分析条件为线性方式和反射方式相结合,可准确、快速确定水解胶原蛋白粉的分子...     

Characterization of polyoxyalkylene block copolymers by combination of different chromatographic techniques and MALDI-TOF-MS

Polyoxyalkylene diblock copolymers (consisting of PEO as hydrophilic block and PBO or PHO as hydrophobic block) are characterized by combination of two dimensional liquid chromatography and MALDI-TOF-MS. Liquid chromatography under critical conditions (LCCC) is used as first dimension and fractions are collected, mobile phase evaporated and diluted in the mobile phase used in the second dimension (SEC, LCCC or LAC). This two-dimensional chromatography in combination of MALDI-TOF-MS gives information about purity of reaction products, presence of the byproducts, chemical composition and molar mass distribution of all the products.     

Enhancing plasma peptide MALDI-TOF-MS profiling by mesoporous silica assisted crystallization

Promising profiling techniques based on new material/solid phase extraction for capturing “molecular signatures” from body fluids are being coupled to MALDI-TOF-MS. Sample preparation significantly influences spectrum quality in this ionization method. Mesoporous silica beads (MSB), by the means of nano-sized porous channels with high surface area, enable harvesting of peptides from plasma and serum excluding large size proteins. We have investigated the morphology of a sample slurry, developed as a new tool for plasma peptides enrichment based on mesoporous materials. Our study highlights a correlation between crystals morphology and enhanced performances in MALDI-TOF-MS analysis. This is the first report which correlates the increase in signal intensity with crystal formation in samples preparations which make use of various kinds of slurries for the analysis of samples clinically relevant like human plasma.     

应用激光解吸电离飞行时间质谱法研究芳香聚硫醚醚砜环状低聚物

应用激光解吸电离飞行时间质谱法对芳香环状聚硫醚醚砜低聚物结构进行了分析,比较了四种不同基质对环状物结构分析结果的影响,发现1,8,9-蒽三酚为此类芳香环状低聚物的有效基质。探讨了金属阳离子对此类芳香环状低聚物的影响,认为三氟乙酸银是此种芳香环状低聚物的有效阳离子剂。     

Analysis of human histone H4 by capillary electrophoresis in a pullulan-coated capillary,LC-ESI-MS and MALDI-TOF-MS

The object of the present study was the analysis of the human histone H4 (a core histone) in order to evaluate the state of its acetylation. Capillary electrophoresis (CE) using a pullulan-coated capillary provides a rapid and efficient approach to the separation of monoacetylated, diacetylated and triacetylated H4 isoforms from human cells. By using a simple running buffer of 100 mM triethanolamine-phosphate solution at pH 2.5 and exploiting the effectiveness of pullulan-based coverage in preventing adsorptive phenomena, the separation of the differently acetylated isoforms was achieved in less than 15 min with high efficiency and reproducibility. The proposed method was for the first time applied in the analysis of histone H4 fractions obtained from cell lines treated with different histone deacetylase (HDAC) inhibitors, used as potential anticancer drugs. Matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) analysis demonstrated that the acetylation occurred in the histone H4 tail, whereas the CE separation allowed for a fast determination of the percentages of H4 acetylated isoforms in real samples; the results were in agreement with those obtained from liquid chromatography electrospray ionisation mass spectrometry (LC-ESI-MS) analysis. Therefore, the proposed CE method is a useful complementary support to the hyphenated techniques for the rapid monitoring of the activity of HDAC inhibitors.     

Coupling microchip electrophoresis with MALDI-TOF-MS based on a freezing technique

A freezing technique protocol was proposed for coupling microchip electrophoresis with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALD1-TOF-MS).The microfluidic flow was frozen immediately after electrophoresis on microfluidic chip and the separated analyte molecules were kept in their zone pattern in the electrophoresis.Then,the frozen-chip was lyophilized and sent into TOF-MS instrument as a MALDI target,and the analyte molecules in the microfluidic channels were subjected to analysis by mass spectrometry.This approach could eliminate sample cross-contamination, providing a new interface for microchip electrophoresis and MALDI-MS.     

用MALDI-TOF-MS法表征系列环状预聚体

应用基质辅助激光解吸电离飞行时间质谱（MALDI－TOF－MS）技术对系列环状预聚体进行了表征,分别确定了系列环状预聚体各自不同的聚合度,同时对它们的结构进行了确认,获得了满意的结果。实验结果表明MALDI－TOF－MS是分析环状预聚体准确、快速工具之一。     

Synthesis and MALDI-TOF-MS of PS-PMA and PMA-PS block copolymers

The synthesis of well-defined block copolymers from styrene and methyl acrylate via ATRP is discussed in this contribution. Kinetic studies on these block copolymerizations as well as characterization studies were performed to investigate the monomer composition in the respective PS and PMA blocks. MALDI-TOF-MS was performed to clarify the exact number of repeating units of each block and the total number of units in the block copolymer. Block copolymers up to 22 kDa could be analyzed by MALDI-TOF-MS, whereby polymers with PMA as first block showed a large second distribution corresponding to PMA homopolymers. However, SEC demonstrated that only a small amount of homopolymer was present indicating that care needs to be taken with interpreting MALDI-TOF-MS data, which is a qualitative rather than a quantitative technique.     

臭氧降解法制备壳低聚糖及其结构表征

以85％脱乙酰度、相对分子质量为25×10^4的壳聚糖为原料,在20℃、pH为3、氧气流量0．7m^3／h的条件下降解6h,降解液用氨水调至pH为9,无沉淀,分别用截留相对分子质量为2k、3k、5k、10k的中空纤维膜超滤,获得所需聚合度的壳低聚糖。降解产物的结构用红外光谱、核磁共振碳谱表征,结果说明降解前后的结构基本没有变化。降解产物的聚合度用飞行时间质谱表征,其中经过2k中空纤维膜超滤后的壳低聚糖聚合度主要为4～10。     

芳香环状聚酯二聚体的结构表征

通过基质辅助激光解析电离飞行时间质谱以及核磁共振技术对芳香环状聚酯二聚体的结构进行了表征.质谱分析结果发现除了目标化合物的质子化分子离子峰外,未出现更多的碎片峰,而核磁共振结果对芳香环状齐聚物的氢以及碳的位置给予了确认.从而为芳香环状齐聚物的结构分析提供了一种新的分析方法.     

Characterization of oligomeric polypropyleneglycol acrylate by GC, SFC and MALDI-TOF-MS.

Polypropyleneglycol acrylate (PGA), one of the typical acrylic oligomers manufactured industrially, was comprehensively characterized by gas chromatography (GC), supercritical fluid chromatography (SFC) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The homologous series of polypropyleneglycol diacrylate (DA), polypropyleneglycol monoacrylate (MA), and unreacted polypropyleneglycol (PG) were observed as Na adducts in the MALDI-MS spectra of the PGA samples. The relative intensities of these peaks reflect the distributions of the homologues, although their accurate quantification was generally difficult because of change in the ionization efficiency depending on the chemical structure and the molecular weight of the species. On the other hand, the DA and the MA homologues were observed in the chromatograms obtained by SFC in a temperature-programming mode, while the PG homologues were not detected under the given SFC conditions using UV detection. Here, the determination of the degree of polymerization of each component in the chromatograms was accomplished through SFC fractionation for the corresponding peaks, followed again by MALDI-TOF-MS measurement. Furthermore, most of the components in the PGA samples were almost completely separated in the resulting gas chromatograms, and their unequivocal assignments were made also using the retention data on the gas chromatograms of the SFC fractions. As for the quantitative analysis, the relative abundances among DA, MA and PG for lower degrees of polymerization can be easily calculated based on the observed gas chromatograms, whereas the distribution of DA and MA can be estimated from the observed SFC data even for the relatively higher molecular weight fractions, which are generally difficult to determine accurately by GC because of their lower volatility. These results demonstrated that even the complex PGA samples were able to be characterized in detail by using GC, SFC and MALDI-TOF-MS complementarily.     

Characterization of Metallo-Supramolecular Systems by MALDI-TOF Mass Spectrometry

MALDI-TOF mass spectrometry was used for the characterization of metallo-supramolecular coordination arrays with molecular weights between 500 and 4000 g/mol. The stepwise loss of the counterions was used as an additional fingerprint for the investigated species. The isotope pattern yielded further information, especially in combination with simulations.     

MALDI-TOF-MS用于组合化学肽库的鉴定

组合化学是一种快速制备大量相关化合物,并可快速对其进行生物活性筛选的革新性的技术和方法。组合化学法自问世以来在生命科学和医药科学技术等领域获得了飞速发展。组合化学肽库已成为同时制备大量不同序列多肽的方法,并已广泛用于抗原决定簇、生物分子相互作用、亲和抑制剂、新药筛选等研究。在亲和筛选研究中,合成组合肽库的评价以及结构鉴定是研究成败的关键步骤之一。     

Characterization of interaction between doxycycline and human serum albumin by capillary electrophoresis‐frontal analysis

The binding of doxycycline to HSA under simulated physiological conditions (pH 7.4, 67 mM phosphate, I=0.17, drug concentration 100 μM, HSA concentration up to 475 μM, 36.5°C) was studied by CE‐frontal analysis. The number of primary binding sites, binding constant and physiological protein‐binding percentage were 1.9, 1.51×10³ M^?1 and 59.80%, respectively. In addition, the thermodynamic parameters including enthalpy change (ΔH), entropy change (ΔS) and free energy change (ΔG) of the reaction were obtained in order to characterize the acting forces between doxycycline and HSA. Furthermore, to better understand the nature of doxycycline–HSA binding and to get information about potential interaction with other drugs, displacement experiments were performed. The results showed that doxycycline binds at site II of HSA.     

MALDI-TOF-MS法对重组人内皮抑素蛋白分子质量测定

肿瘤的生长依赖于血管的生成,新生血管不仅为肿瘤生长提供必需的营养物质,而且为肿瘤细胞扩散提供了重要的途径。1997年哈佛大学的O'Reilly等发现了一种内源性新血管生成抑制因子内皮抑素(Endoscatin),显示出特异抑制激活的血管内皮细胞增殖和肿瘤新血管生成的生物学活性,其抗肿瘤作用具有高效、低毒、无耐药性的优点。目前,内皮抑素的研究引起了国内外广泛的兴趣,在美国已进行以安全性为目的的I期临床实验,国内也有多家公司对内皮抑素进行了抗肿瘤研究并申报一类新药。内皮抑素有望成为医治肿瘤而又没有化疗和放疗的毒副作用的一种新的治疗方法,但是否能作为药物应用于临床,尚需对内皮抑素的结构特点及抑制肿瘤和内皮细胞的作用机制等方面进行许多深入的研究。     

Investigation of the Structure of Polymerizable Silsesquioxanes by GPC and MALDI-TOF-MS in Relation to their Viscosity

Summary. Hydrolytic condensation of different methacrylate groups containing alkoxy silanes yielded resins which showed interesting properties as a matrix for dental composites. For this purpose, resins of low viscosity are desired resulting in composites with a high amount of inorganic fillers. Our investigations demonstrated that the viscosity of the obtained polycondensates was predominantly influenced by the kind of organic spacer between the methacrylate group and the silicon atom. In addition, the viscosity also significantly changed in dependence of the kind of structure units built. NMR spectroscopic investigations as well as size exclusion chromatography (SEC) and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry showed that the formed structures depended both on the kind of catalyst used for hydrolysis/condensation and the bulkiness of the organic substituent at the silicon atom.     

A simple protocol for Matrix Assisted Laser Desorption Ionization- time of flight-mass spectrometry (MALDI-TOF-MS) analysis of lipids and proteins in single microsamples of paintings

A simple protocol, based on Bligh–Dyer (BD) extraction followed by MALDI-TOF-MS analysis, for fast identification of paint binders in single microsamples is proposed. For the first time it is demonstrated that the BD method is effective for the simultaneous extraction of lipids and proteins from complex, and atypical matrices, such as pigmented paint layers. The protocol makes use of an alternative denaturing anionic detergent (RapiGest™) in order to improve efficiency of protein digestion and purification step. Detection of various lipid classes, such as triacylglycerols (TAGs) and phospholipids (PLs), and their oxidation by-products was accomplished, whereas proteins could be identified by peptide mass fingerprinting. The effect of pigments on ageing of lipids and proteins was also investigated.     

Simultaneous Analysis of Phosphorylated Peptides by MALDI-TOF-MS

Six peptides with various phosphorylation sensitivities for protein kinase A (PKA) were used for the simultaneous analysis of phosphorylated peptides using matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry. The mixture of six peptides was reacted with PKA and was analyzed by MALDI-TOF mass spectrometry. The intensity of all peaks except one phosphorylated peptide peak was very low (<20%). Moreover, we examined whether the addition of diammonium citrate to CHCA matrix at concentrations of 1–20 mg mL^?1 can increase the peak intensity of peptides and phosphorylated peptides. The addition of diammonium citrate increased the peak intensity of peptides and phosphorylated peptides, but an increase in the intensity was unsatisfactory. Our study strongly suggests that MALDI-TOF mass spectrometry is not suitable for the simultaneous analysis of phosphorylated peptides.