N-磷酰化肽酯及小肽与氨基酸相互作用的ESI-MS研究

采用ESI-MS研究了一系列结构具有可比性的N-二异丙氧基磷酰化肽酯及小肽同20种蛋白氨基酸及3种D型氨基酸(D-Ala、D-Ser、D-Phe)的非共价相互作用。结果表明,可形成π-π共轭体系的芳香环,可显著增强磷酰化肽酯及小肽与氨基酸的相互作用力,π-π堆积力是首要的非共价相互作用力;可形成氢键的极性基团有利于形成复合物,但能否形成氢键还要受到分子柔顺性的影响;另外,分子大小、空间位阻对复合物的形成也有影响;而氨基酸的手性对它们的相互作用在质谱条件下没有表现出影响。     

N-磷酰化多巴胺与溶菌酶相互作用的ESI-MS研究

采用电喷雾离子肼-质谱(ESI-MS)研究了一系列结构具有可比性的N-磷酰化多巴胺与溶菌酶的非共价相互作用,比较了磷上不同取代基对相互作用的影响.结果表明,磷上的烷氧取代基上烷基碳原子的个数及排列顺序对二者相互作用有较大影响;取代基上碳链越长,溶液中溶菌酶的构象越趋于收缩,二者之间越容易形成带低电荷和高质核比的复合物,且其稳定性也随着取代基的增长而增强;当取代基碳原子数相同时,直链取代的磷酰化多巴胺与溶菌酶形成的复合物比支链取代的底物与溶菌酶形成的复合物稳定.     

ESI质谱法对黄酮-7-磷酰化氨基酸酯与溶菌酶相互作用的研究

采用电喷雾(ESI)质谱技术,研究了4种黄酮-7-磷酰化氨基酸酯与溶菌酶的弱相互作用,实验结果表明4种化合物均能与溶菌酶形成非共价复合物,在相同条件下,未检测到黄酮与溶菌酶形成的非共价复合物,说明在黄酮分子中引入N-磷酰化氨基酸,能改变黄酮的分子极性,从而使其与生物大分子之间的相互作用情况发生变化;通过改变锥孔电压,分别对4种黄酮-7-磷酰化氨基酸酯-溶菌酶复合物的耐压能力进行检测.结果显示,黄酮-7-磷酰化氨基酸酯b与溶菌酶形成的复合物最稳定,它们之间存在最强的弱相互作用.     

大豆苷元磷酰化衍生物的合成及其与溶菌酶复合物的ESI研究

通过改进的Atherton-Todd反应,得到了5个新的大豆苷元磷酰化衍生物,其结构被X-ray,IR, NMR和ESI确认. ESI质谱证实在气态下磷酰化大豆苷元能和溶菌酶形成非共价复合物,而大豆苷元与溶菌酶的非共价复合物未能检测到. 通过变换ESI的orificevoltage,检测了不同的磷酰化大豆苷元与溶菌酶非共价复合物的相对稳定性.     

荧光及ESI质谱法研究溶菌酶与磷酰化黄酮的相互作用

分别用荧光法和ESI质谱法研究了磷酰化黄酮和溶菌酶的相互作用 .结果均显示磷酰化黄酮能够和溶菌酶发生弱相互作用 ,与黄酮相比它对溶菌酶更具亲和力 .根据荧光猝灭双倒数图计算了磷酰化黄酮与溶菌酶之间的结合常数为k2 0℃ =1.68× 10 4L/mol,k3 7℃ =1.0 6× 10 4L/mol,实验证明随着温度的升高 ,磷酰化黄酮与溶菌酶的结合常数逐渐降低 ,说明了两者之间形成了复合物 ,此荧光猝灭过程为静态猝灭 .根据F ster能量传递原理计算出磷酰化黄酮在溶菌酶上的结合距离 ,并根据热力学参数确定了磷酰化黄酮与溶菌酶之间的作用力类型为电荷作用力     

N,N-二取代甘氨酸酯的ESI-MS/MS研究

应用多级质谱（＋）ESI—MS／MS考察了八种N,N-二取代甘氨酸酯化合物的质谱行为,并对其质谱裂解途径进行解析,为表征该类化合物提供了依据。     

ESI-MS研究N-苯甲酰基-脱氢枞胺衍生物与血管紧张肽Ⅲ的相互作用

采用电喷雾质谱法,考察了4种最新合成的N-苯甲酰基-脱氢枞胺衍生物（NBDD）——N-苯甲酰基-脱氢枞胺(NBD),N-邻氯苯甲酰基-脱氢枞胺(NClBD),N-苯甲酰基-脱氢枞胺-7-酮(NBDO),N-邻氯苯甲酰基-脱氢枞胺-7-酮(NClBDO)与具有重要生理作用的血管紧张肽Ⅲ（AngⅢ）的相互作用。结果表明,这4种化合物与AngⅢ以不同的摩尔比 (1:1,3:1,5:1)混合时,均可形成非共价复合物,并主要形成+2价复合物离子。对4种NBDD:AngⅢ为1:1的+2价复合物离子[NBDD-AngⅢ+2H]2+进行了2级质谱分析,并根据相对碰撞能的大小,比较了这4种复合物离子的稳定性。对NBDD:AngⅢ为2:1的+2价复合物离子[(NBDD)2-AngⅢ+2H]2+进行了2级和3级质谱分析,并探讨了(NBDD)2-AngⅢ复合物中NBDD分子与AngⅢ的结合方式。     

磷酰化对丙氨酸与溶菌酶相互作用的影响

在电喷雾离子阱质谱图中发现丙氨酸不能和溶菌酶形成二聚体, 而磷酰化丙氨酸(DIPP-Ala)能和溶菌酶形成二聚体. 进一步研究发现丙氨酸及其他氨基酸磷酰化后, 自身形成二聚能力大大增强. 在Silicon Graplics图形工作站上采用SYBYL 6.8软件, 利用Tripos力场和分子力学方法研究了DIPP-Ala最低能量构象, 并用分子对接(DOCK)研究了二聚体的形成. 结果说明磷氧双键的存在增强了分子间的相互作用.     

水溶液中磷酰化组氨酸与其它氨基酸的交叉成肽研究

水溶液中磷酰化组氨酸与其它氨基酸的交叉成肽研究沙耀武，赵玉芬（清华大学化学系，北京１０００８４）一些氨基酸在前生化时期的条件下，就可以由甲烷、氨和水通过高压放电生成［１，２］。如果向该反应体系中加入三氢化磷，生成的氨基酸的种类增多、结构的复杂性也提高...     

电喷雾质谱法研究人参皂苷与溶菌酶的相互作用

用电喷雾质谱法研究了溶菌酶与人参皂苷Rg1和Re的非共价相互作用。非共价复合物的解离常数可以由溶菌酶和复合物的峰高直接计算得到。由各个体系得到的溶菌酶与Rg1和Re的一级解离常数KD, 1是一致的,但是二级解离常数KD, 2的差别较大。由此可以推断出复合物的峰高越强,结果的精密度越好。当固定溶菌酶的浓度不变时,复合物的解离常数会随着人参皂苷的浓度的增加而略微的增大。而当固定人参皂苷的浓度时,复合物的解离常数会随着溶菌酶的浓度的增加而减小。计算结果还证明了人参皂苷Rg1与溶菌酶的结合能力大于Re。     

Direct Observation of Non-covalent Complexes for Phosphorylated Flavonoid-protein Interaction by ESI

Diethyl flavon-7-yl phosphate was synthesized by modified Atheron-Todd reaction. The result of ESI shows that the phosphated flavonoids possess stronger binding affinities toward proteins such as myoglobin, insulin and lysozyme and are easier to form the non-covalent complexes with them.     

Synthesis of Novel Phosphorylated Daidzein Derivatives and ESI Investigation on Their Non-Covalent Complexes with Lysozyme

Daidzein （7,4＇-dihydroxyisoflavone） was phosphorylated by a modified Atherton-Todd reaction. The structures of the five target product, were determined by X-ray, IR, NMR and ESI-MS. Electrospray ionization results show that in the gas phase all the phosphorylated daidzein derivatives could form non-covalent complexes with the protein lysozyme, while non-covalent complexes were not detected in the mixed solution of daidzein with lysozyme. Relative affinity of every non-covalent complex was obtained according to its different decomposition orifice voltage.     

Studies on Aggregation Interaction between Reduced Denatured Egg White Lysozymes during Refolding Procedure in Urea Solution

The aggregation interaction between reduced-denatured egg white lysozymes during refolding procedure in urea solution was studied by means of reducing and non-reducing protein electrophoreses. Results of non-reducing sodium dodecyl sulphate polyacrylamide gel electrophoresis （SDS-PAGE） of the supernatant and aggregate precipitate formed in refolding process show that except being refolded to native egg white lysozymes, the reduced-denatured lysozymes can also form the aggregates with molecular weights （MW） being separately about 30.0 and 35.0 kD, while the reducing SDS-PAGE and the refolding results in the presence of sodium dodecyl sulphate show that these aggregates are formed chiefly through the misconnection of disulfide bonds between the reduced-denatured lysozymes, and the aggregate precipitates are formed through the non-covalent interactions between the aggregates with molecular weight being about 30.0 kD. From the results of electrophoresis and size-exclusion chromatographic analyses, it can be inferred that the aggregates with molecular weights being about 30.0 and 35.0 kD are bi-molecular and tri-molecular egg white lysozyme aggregates, respectively. And finally, a suggested refolding mechanism of reduced-denatured egg white lysozymes in urea solution was presented.     

气相色谱法在生物柴油生产工艺研究中的应用

综述了气相色谱法在生物柴油生产工艺研究中的应用,包括反应产物和生物柴油产品中脂肪酸甲酯含量和分布的测定,单脂肪酸甘油酯、二脂肪酸甘油酯和三脂肪酸甘油酯含量的测定,游离脂肪酸含量的测定以及微量甲醇含量的测定等。讨论了进样方式、色谱柱类型、硅烷化等因素对反应产物组成测定的影响;提出了一种采用双柱压力反吹的方式测定生物柴油产品中微量甲醇含量的方法：采用正丙醇作内标,甲醇与内标通过预切柱进入分析柱后,通过压力变化,将其余组分通过分流出口反吹出色谱系统;采用极性聚乙二醇色谱柱测定了8种不同植物油中脂肪酸甲酯的含量和分布。     

类黄酮化合物对G-四链体及双链DNA选择性的电喷雾质谱研究

利用电喷雾质谱(ESI-MS)研究了4种常见的类黄酮化合物芦丁、槲皮素、葛根素和柚皮苷与2种不同形态结构的G-四链体DNA和3种双链DNA的非共价相互作用,比较了这些小分子化合物与不同形态结构DNA结合的强弱及形成复合物的化学计量.结果表明,芦丁和槲皮素对G-四链体DNA具有一定的选择性,同时它们对双链DNA的选择性也较高;而葛根素和柚皮苷对G-四链体DNA仅显示了较低的选择性.     

Analysis of the Triglycerides and the Free and Derivatized Fatty Acids in Fish Oil by Capillary Electrochromatography

Capillary ElectroChromatography (CEC) on a fused silica capillary column (40 cm L × 100 μm i.d.) packed with 3 μm octadecylsilica (ODS) was evaluated for the analysis of the triglycerides and their fatty acids in fish oils, and more especially in the oil of Moroccan Sardinia pilchardus. The very high complexity of the lipids in fish oil is well illustrated by CEC with a nonaqueous mobile phase consisting of acetonitrile/isopropanol/n-hexane in the ratio 57/38/5 to which 50 mM ammonium acetate has been added. In order to unravel the complexity, the oil was hydrolyzed and the free fatty acids (FFAs), the methyl esters (FAMEs), and the phenacyl esters (FAPEs) were analyzed by CEC on the same column used for the analysis of the triglycerides. Isocratic elution was achieved with the mobile phase acetonitrile/50 mM MES pH 6 in ratio 9/1. The migration characteristics of FFAs, FAMEs, and FAPEs are compared. The analysis of FAPE derivatives has the advantage that quantification applying UV detection is possible and moreover that the number of double bonds in the fatty acid chains can be elucidated by measuring the UV abundance ratio 240/210 nm.     

Hydrolysis of Dipeptide Heptyl Esters with Newlase F

Peptides conjugates, such as lipo-, glyco-, phospho- and nucleopeptides1, are of great importance in the research of signal transmission2, protein phosphorylation/ dephosphorylation, antibody, and so on. However, the synthesis of these compounds is severely complicated by their pronounced acid and base lability as well as their multifunctionality. Under basic or acidic conditions, (-elimination reactions, anomerization, hydrolysis or rupture of these compounds may occur. The traditional peptid…