纳升电喷雾串联质谱法确证阿托西班的一级结构

利用电喷雾串联质谱对合成八肽阿托西班进行了二硫键还原前后的精确分子量测定和一级结构的确证.首先通过全扫描模式测定了其还原前后的精确分子量,然后选择母离子m/z 498.73(双电荷)通过串联质谱(MS/MS)得到碎片离子,采用Y离子的方法测定了阿托西班的序列并对其的修饰位点进行了确证.本方法具有灵敏度高、速度快、样品无需纯化等特点,在多肽类药物一级结构分析方面具有独特的优势.     

反相高效液相色谱-电喷雾质谱法分析食源血管紧张素转换酶抑制肽

利用反相高效液相色谱/电喷雾离子阱质谱法,直接分析从牦牛乳酪蛋白中酶水解得到的血管紧张素转换酶抑制肽粗产物。RP-HPLC显示具有活性的多肽粗产物含有3个主要成分,质谱同步测定各组分的分子量(m/z)分别为815.2,1680.1,962.2,然后选择[M H] 离子通过串联质谱(MS/MS)得到碎片离子,利用b离子和y离子互补的方法鉴定了多肽序列。三条肽分别为Leu-Pro-Tyr-Tyr,Pro-Leu-Pro-Leu-Leu-Gln,Phe-Leu-Pro-Pro-Tyr-Tyr。结果显示,所获得的多肽序列与牛乳酪蛋白一级结构中相应肽段的序列一致。     

SNP的电喷雾串联质谱研究

采用电喷雾串联质谱技术对两组单核苷酸多态性(SNP)样品进行了研究,初步研究结果显示应用串联质谱可快速鉴定SNP分型以及确定SNP位点。采用16.3 mmol/L三乙胺(TEA)-400 mmol/L六氟异丙醇(HFIP)缓存溶液,电喷雾负离子模式下,长度为20 bp的寡核苷酸的MS扫描谱图显示其母离子呈较宽的多电荷态分布。选择低电荷态[M-4H]4-母离子,碰撞能为54 eV时,MS/MS扫描得到丰富的碎片离子,通过鉴定特征离子碎片(w和a-B离子系列)可确定其序列。     

基质辅助激光解析电离质谱和电喷雾质谱共同快速确证达托霉素结构

运用基质辅助激光解析电离-飞行时间串联质谱(MALDI-TOF/TOF MS)和电喷雾-四级杆-飞行时间质谱(ESI-Q-TOF MS)快速确证环脂肽达托霉素的结构。首先,ESI检测达托霉素相对分子量为1619.7107,与理论值偏差0.0007。选择其双电荷峰m/z 809.848作为母离子进行ESI串联质谱(MS/MS)测定,成功匹配了达托霉素环外氨基酸序列C9H19CO-Trp-Asn-Asp。其次,优化Li OH裂解达托霉素的实验条件,以MALDITOF/TOF MS监测开环效果,获得95%以上的开环样本后,分别运用MALDI和ESI进行MS/MS测定,达托霉素开环产物的b+和y+全部被匹配,达托霉素全部氨基酸序列得到确证。最后,对开环产物的ESI-MS/MS条件进一步优化,获得了丰富的低端碎片离子,解析了脂肪酸链结构,并绘制了脂肪酸链的裂解图。本方法快速、简便、准确,是确证环脂肽类化合物结构的可靠方法。     

人肝癌细胞系HLE细胞表面抗原多肽的纳升电喷雾串联质谱从头测序分析

肿瘤细胞表面的抗原多肽能够被细胞毒T淋巴细胞特异性识别而引起免疫应答,因此有可能用于研制基于多肽的抗肿瘤疫苗。用弱酸将人肝癌细胞系HLE细胞表面抗原多肽和人正常肝细胞表面多肽洗脱后,经RP-HPLC分离,选择HLE细胞表面特异性多肽进行纳升电喷雾串联质谱(nanoESI-MS/MS)测序,共测定5个色谱峰中的20个多肽序列,分子量分布范围为1000~2000 Da。借助M asSeq软件分析出其中12个多肽的序列。经数据库查寻,其中的3个肽段分别来自钙调节蛋白、核蛋白S19和伴侣蛋白10。这些多肽的生物学功能及与肿瘤的关系值得深入研究。该研究表明nanoESI-MS/MS是测定微量混合多肽序列的最有效方法。     

纳升电喷雾串联质谱在阿托西班一级结构确证中的应用

利用电喷雾串联质谱对合成八肽阿托西班进行了二硫键还原前后的精确相对分子质量测定和一级结构的确证.首先通过全扫描模式测定了其还原前后的精确相对分子质量,然后通过串联质谱(MS/MS)得到母离子m/z 498.73(双电荷)的碎片离子,采用y离子的方法测定了阿托西班的序列并对其修饰位点进行了确证.该方法具有灵敏度高、速度快、样品无需纯化等特点,在多肽类药物一级结构分析方面具有独特的优势.     

超高效纳升液相色谱-电喷雾串联质谱鉴定重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白

采用超高效纳升液相色谱-电喷雾串联质谱对重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白进行了分析.样品经胰蛋白酶酶切后,进行液相色谱-串联质谱分析和数据库检索.结果表明, 分别有5个和7个肽段匹配于人肿瘤坏死因子受体和人Ig gamma-1 chain C region.比对分析表明,重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白中检测到的人IgG的7个肽段完全与人IgG1的序列匹配,与其它3个亚型只有部分肽段匹配.说明重组人Ⅱ型肿瘤坏死因子受体-抗体融合蛋白一级结构正确,Fc片段确实为人IgG1的Fc片段.     

合成多肽的电喷雾质谱研究

利用电喷雾多极串联质谱对3种合成多肽进行了系统的鉴定和分析研究。首先通过全扫描模式测定了其分子量，然后选择[M H]^ 或[M 2H]^2 离子通过串联质谱(MS／MS)得到碎片离子，采用y离子和b离子互补的方法测定了多肽序列。利用文献数据对这种方法进行了验证，实验结果表明，该方法简便、快速、实用。     

纳升电喷雾串联质谱(Q-TOF)测序中Na+加合肽的分析

电喷雾串联质谱测序法是蛋白质组研究中蛋白质鉴定的最有力的手段之一。肽段离子在ESI-Q-TOF中往往以多电荷形式出现(2～4个电荷),其中m／z在500～1000之间带双电荷的离子最适合测序。但这样的肽段很容易和Na+加合,有时加合峰的相对强度比原肽段高很多,有时甚至只有加合峰。Na+加合肽的序列分析比较困难,因数据库查寻不支持Na+加合,且Na+加合是非氨基酸特异的,序列分析中不能按修饰编辑,一旦有一个氨基酸的序列发生偏差,整个肽段序列就不正确。因此,Na+加合肽的序列分析很重要。在Na+加合肽序列分析中,寻找m／z相差22Da的离子,以其为起点分别按m／z从高到低和从低到高进行分析,可得到完整序列,用序列进行数据库检索可鉴定蛋白质,本文用此方法分析了5个Na+加合肽的序列,鉴定5个蛋白质。Na+加合位点分别为丝氨酸S、脯氨酸P和酪氨酸Y。     

反相高效液相色谱法测定蟾酥中的3种蟾毒内酯

建立了一种基于毛细管反相液相色谱-串联质谱联用技术和质谱峰强度数据处理的肽段鉴定和相对定量分析方法。该方法无需对样品中的肽进行化学标记,在对样品进行反相色谱分离和串联质谱分析后,将二级质谱扫描数据进行蛋白质数据库搜索,获得所鉴定肽段的序列、保留时间、质荷比、带电荷数等定性信息;再以此为定位依据,在全扫描质谱数据中提取该肽段对应的离子峰并以该离子峰的峰强度作为定量信息,从而实现对不同样品中的共有肽段进行差异比较分析。以标准蛋白酶解混合肽段为实验对象,以肽段相对强度的相对标准偏差为指标,考察了该方法用于肽段相对定量分析的重现性、检测动态范围以及浓度标准曲线等,为将该方法用于生物样品中内源性肽的差异分析奠定了基础。。     

利用手持技术改进测定乙醇分子结构实验

利用压强传感器代替排水集气法,改进测定乙醇分子结构实验的仪器装置,并探索最佳反应条件。另外,设计两个空白实验,结合压强变化曲线对实验误差进行相关讨论。     

Neutral diterpenoids of oleoresins of five species of conifers of Transcarpathia

The compositions of the neutral diterpenoids of the oleoresins of five species of conifers growing in the Transcarpathia have been studied. It has been found that the oleoresins ofAbies alba M.,Larix decidua M., andPicea excelsa L. contain more than 50% of neutral diterpenoids. The group and qualitative compositions of the oxygen-containing diterpenoids have been determined. In the oleoresins ofAbies alba,Picea excelsa, andPicea abies tertiary alcohols — cis-abienol and isocembrol — predominate, while inLarix decidua the main component is the hydroxy ester larixyl acetate. Primary alcohols related to the resin acids have been found in all the oleoresins investigated. Features of the distribution of diterpenoids according to the species of conifers have been revealed. The results obtained are necessary for the chemotaxonomy of conifers of the family Pinceae.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Academy of Sciences of the USSR. Translated from Khimiya Prirodynkh Soedinenii, No. 6, pp. 812–816, November–December, 1988.     

光谱仪测试范围的扩展

由于石化行业的生产需要，其材质的使用具有多样性和广泛性，经常会出现顾客委托的测试样品的一个或几个元素跨越光谱仪现有测试程序测量范围的情况。本法通过对光谱仪测试原理的认识，根据光谱仪的测试能力及标样的采集，实现了一个或几个元素测量范围的扩展，并对其测量的影响因素进行了研究。     

Dichroism of absorption and polarization of phosphorescence of molecules of the closed form of nitrobenzospirothiopyran

The spectral-polarization characteristics of absorption and phosphorescence of molecules of the initial form of nitro-substituted indolinospirobenzothiopyran were studied in oriented polyethylene films and in solutions with different polarity. An oscillator model of the electron transitions responsible for the formation of absorption and luminescence spectra was suggested. It was established that the principal differences in the spectral and photophysical properties of the compound studied and its oxygen-containing analog are associated with the fact that the electronegativity of the S atom is lower than that of the O atom. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1143–1146, June, 1997.     

Influence of viscosity of medium on processes of oxygen quenching of excited states of mesoporphyrin

The oxygen quenching rate constants for singlet and triplet excited states of the dimethyl ester of mesoporphyrin IX increase with decreasing viscosity of the medium and reach a maximum at a viscosity of approximately 0.4 mPa·sec, after which the rate constants begin to decrease. The drop in rate constant with increasing fluidity of the medium may be related to a nonequilibrium character of the elementary act in the interaction of the reactants in the solvent cage. In viscous media such as isopropyl alcohol, isobutyl alcohol, and isoamyl alcohol, the reaction radius is greater than the sum of the radii of the reacting particles. The long-range character of these processes is due to the relatively weak dependence of the quenching probability on distance.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 2, pp. 161–167, March–April, 1989.     

Determination of heats of detonation and influence of components of composite explosives on heats of detonation of high explosives

The heats of detonation of 20 simple high explosives and explosive mixtures were determined by means of an adiabatic detonation calorimeter designed by the authors. The results indicated that the performance of the instrument was reliable and the experimental data were very accurate. For explosive mixtures, there was a linear accumulative relationship between the heats of detonation of the explosive mixture and its components. Accordingly, the heats of detonation of explosive mixtures could be calculated directly from the heats of detonation of simple explosives and the characteristic heats of other components. The experiments showed that the gold or brass shell of the cylindrical charge could be substituted by a thick-walled porcelain shell, which had the advantage of cheapness.

     

物质分配系数的测定实验改进

实验教学目的是从解决实际问题出发,以实验技术训练和实验设计思想培养为目标。介绍了将单一的物质分配系数测定实验改进为综合实验,提高了实验效果及实验资源利用率。     

Calculation of enthalpies of hydrogenation of hydrocarbons

Sets of hydrogen molecule equivalents have been developed which permit the calculation of hydrogenation of different types of carbon-carbon bonds from ab initio total energies (3-21G and 6-31G* basis sets, and, to a more limited extent, for MP2/6-31G* data) of reactants and products. The calculated enthalpies of hydrogenation are in good agreement with experiment for unstrained molecules, with average errors on the order of 2 kcal/mol. The 6-31G* equivalents allow the enthalpies for strained molecules to be calculated accurately, but the 3-21G equivalents do not. The equivalents for both basis sets have been tested by calculating the enthalpies of hydrogenation of carbon-carbon bonds in nitrogen- and oxygen-containing organic molecules, free radicals, and classical carbocations. The results are in good agreement with experiment in most cases.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。