Synthesis of cyclic precursors of poly(ether ether ketone)

A novel synthetic route to cyclic PEEK precursors is described. These new cyclic oligomers have been prepared from hydroquinone and N-phenyl(4,4'-difluorodiphenyl) ketimine. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis unambiguously confirmed the cyclic nature.

Synthesis and characterization of a water-soluble endohedral metallofullerol

A water-soluble endohedral metallofullerol, Pr@C82Om(OH)(n)(m approximate to 10 and n approximate to 10), was successfully synthesized through the reaction of a pure endohedral metallofullerene, Pr@C-82, with a concentrated nitric acid and a subsequent hydrolysis process. The formation of endohedral metallofullerols Pr@C82Om(OH)(n) is thought to involve a NO2 radical formation step, in much the same way as the reaction of empty fullerenes. FT-IR, XPS, and LD-TOF MS techniques were employed to characterize the structure of the endohedral metallofullerol from the above reaction.

长白山白眉蝮蛇蛇毒酶的基质辅助激光解吸质谱分析

用基质辅助激光解吸飞行时间质谱(MALDI-TOF-MS)法对长白山眉蝮蛇蛇毒所含4种主要酶:磷脂酶A_2、精氨酸酯酶、纤溶酶及L-氨基酸氧化酶进行了纯度鉴定和分子量测定,结果表明WALDI-TO-FMS具有灵敏度高、分辨能力强、分析时间短及样品用量少等优点.用MALDI-TOFMS法分析蛇毒酶的纯度和分子量简捷、快速且重现性好,是SDS聚丙烯酰胺凝胶电泳所无法比拟的.

白眉蝮蛇蛇毒L-氨基酸氧化酶的纯化与表征

用离子交换和凝胶过滤层析技术从长白山白眉蝮蛇蛇毒(A gkistrodon blom hoffii ussurensis)中分离得到了L氨基酸氧化酶(L-amino acid oxidase)，经SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)和基体辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)鉴定，发现L-氨基酸氧化酶由两个不相等的亚基组成，一个亚基的分子量约为36000，另一个亚基分子量约为57000．以L-亮氨酸作为底物进行L-氨基酸氧化酶活力测定时发现，其反应的适宜PH值为45.5和89，紫外吸收光谱明显表现出核黄素蛋白的特征

长白山白眉蝮蛇蛇毒磷脂酶A2的分离和初步表征

东北长白山白眉蝮蛇(Agkistrodon blom hoffii Ussurensis)蛇毒经DEAE-Sephadex A-50离子交换层析柱，连续3步Sephadex G-75凝胶过滤柱得到了磷脂酶A2(PLA2)的纯品。SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)以及基质辅助激光解析电离飞行时质谱(MALDI/TOF/MS)表征为单一蛋白，其准确分子量为(14.008±0.007）kD。最适PH范围8.0～9.0，最适的反应温度为45℃。在溶液中有多聚体的存在。

聚芳醚酮环状低聚物的基质辅助激光解吸电离质谱表征

采用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)技术分别对2种合成的聚芳醚酮环状低聚物进行了分析研究 ,并讨论了低聚物中不同聚合度离子组分的分布规律。实验结果表明MALDI-TOF-MS是分析环状低聚物直观、准确、快速的分析工具。

应用激光解吸质谱和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析蛇毒精氨酸酯酶的纯度和分子量

应用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)和SDS-聚丙烯酰胺凝胶电泳对吉林省两地市的同种白眉蝮蛇蛇毒中具有抗栓塞药效的精氨酸酯酶进行了分析和比较。MALDI-TOF-MS法具有快速、准确度高、灵敏度高的优点,两种方法结合,互为补充,取得了令人满意的结果,MALDI-TOF-MS完全可以直接用作蛇毒成分分离过程中重要的研究手段。

快速和灵敏地分析常见氨基酸

利用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)和电子轰击(EI)质谱法快速、灵敏地分析了常见的八种氨基酸。并讨论了在不同电离方式下这八种氨基酸的质谱行为,分析结果表明两种方法对测定氨基酸均具有独特之处。

Synthesis of novel cyclic aryl ether thioether ketone (Sulfone) oligomers

Two kinds of macrocyclic oligomers containing aromatic sulfide linkages have been synthesized by the solution polycondensation in high yield. The cyclic compounds were characterized by H-1 and C-13 NMR, by and MALDI - TOF MS.

Intensity exaggeration of endohedral metallofullerenes in laser-desorption-ionization time-of-flight mass spectrometry

The laser-desorption-ionization time-of-flight mass spectrometry and desorption-electron-ionization mass spectrometry were employed for the characterization of metallofullerenes extract. it was found that the relative intensities of metallofullerenes in this positive-ion, negative-ion LD-TOF MS and DEI MS were much different. This phenomenon should have relationship with the peculiar ionization energies and electron affinities of metallofullerenes.

Hydrophobic pocket modification and humanized catalytic antibodies with glutathione peroxidase activity (I) - Preparation and characterization of haptenes and conjugates

The thiol group of glutathione (GSH) was protected by 2,4-dinitrochlorobenzene (DNCB), the product S-substituted dinitrophenyl GSH(GSH-S-DNP) was alcoholized to obtain haptenes 4 and 5 respectively. As haptenes, the two GSH derivatives were characterized by means of H-1 NMR, MALDI-TOF-MS and IR, followed by individually coupling with bovine serum albumin (BSA) via glutaraldehyde. BSB-Hp4 and BSA-Hp5 were purified by Sephadex G-25 gel filtration chromatography. For each conjugate, the average haptene-BSA ratio was 12 : 1. The electrophoresis analysis showed that the average molecular weight of each conjugate was 76 500. The CD spectrum indicated that the conjugates had more a-helix content than BSA did.

Synthesis and polymerization of some macrocyclic (arylene ether sulfone) containing cardo groups and macrocyclic (arylene ether ketone sulfone) oligomers

Some novel macrocyclic (arylene ether sulfone) containing cardo groups and (arylene ether ketone sulfone) oligomers have been synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-difluorophenylsulfone with bisphenols in the presence of anhydrous potassium carbonate under a pseudo-high-dilution condition. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), fast atom bombardment mass spectrometry (f.a.b.-m.s.), nuclear magnetic resonance spectrometry (n.m.r.) and single-crystal X-ray structure analysis confirms their cyclic nature, and the composition of the oligomeric mixtures is provided by g.p.c. analysis. Ring polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 59.1 k was achieved by heating at 290 degrees C for 40 min in the presence of a nucleophilic initiator. (C) 1998 Elsevier Science Ltd. All rights reserved.

Macrocyclic oligomeric arylene ether ketones: Synthesis and polymerization

Some novel macrocylic(arylene ether ketone)oligomers were synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-dinitrobenzophenone with bisphenols in the presence of anhydrous potassium carbonate under pseudo-high-dilution conditions. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), H-1 NMR and FT-IR confirmed their cyclic nature and the compositions of the oligomeric mixtures was indicated by GPC analysis. Ring-opening polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 52.3 and M-n of 17.2 k was achieved by heating at 280 degrees C for 40 min in the presence of a nucleophilic initiator.

Characterization of cyclic (aryletherketone)s by matrix-assisted laser desorption ionization time of flight mass spectrometry

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) was used to identify cyclic(aryl ether ketone) oligomers, using 2,5-dihydroxybenzoic acid as a matrix, and Na+ and K+ as cationization agents, The existence of different ring-sized cyclic oligomers up to 9 and their distribution were determined and compared with GPC results, The results indicated that MALDI-TOF MS was a powerful and rapid analytical tool for the cyclic oligomers.

Behavior of silver cluster on laser desorption/ionization time-of-flight mass spectrometry

A successful analysis of silver was reported utilizing laser desorption/ionization time-of-flight mass spectrometry (LDI/TOF-MS) in this paper, The silver cluster ions Ag-n(+) and AgnO+ (n=2 similar to 5) were formed during laser desorption/ionization. In the presence of I-, K+ and Na+, the peaks corresponding, to the cluster ions [AgnIn-1](+) (n=2 similar to 6) and the adduct ions [AgI](+), [AgI]Na+ and [AgI]K+ were observed in the positive ion spectrum; the peaks corresponding to [AgnIn+1](-) (n=1 similar to 3) were found in the negative ion spectrum, all of which accompanied by sliver isotope distribution, The formation of silver cluster ions was accomplished through two-stage reaction: the first step was the generation of clusters, which was followed by the processes of photoionization and ion/molecule reaction.