Elucidation of O-Phosphoryl and N-Phosphoryl Amino Acids by Electrospray Ionization Tandem Mass Spectrometry

Mass spectroscopic characteristics of phosphoryl amino acids were studied in detail by positive and negative electrospray ionization mass spectrometry (ESI-MS) in conjunction with tandem mass spectrometry (MS/MS). Besides N-diisopropyloxyphosphoryl amino acids (N-DIPP-AA), O-phospho- and O-diisopropyloxyphosphoryl amino acids (O-DIPP-AA) were studied and compared to N-DIPP-AA. The fragmentation pathways of [M H]^ ,[M Na]^ and [M-H]^- ions of phosphoryl amino acids were summarized. In addition to several similar patterns, each of them showed its characteristic fragmention.     

Hydrolysis Reaction of N-Phosphoryl-α-, β- and γ-amino Acids Studied by HPLC

The hydrolysis reactions of N-（O,O＇diisopropyl）phosphoryl-L-α-alanine （DIPP-L-α-Ala）, N-（O,O＇diisopropyl）- phosphoryl-D-α-alanine （DIPP-D-α-Ala）, N-（O,O＇-diisopropyl）phosphoryl-β-alanine （DIPP-β-Ala） and N-（O,O＇-diisopropyl）phosphoryl-γ-amino butyric acid （DIPP-γ-Aba）, were studied by HPLC and their hydrolysis reaction kinetic equations were obtained. Under acid conditions, the reaction rate of DIPP-L-α-Ala was close to that of DIPP-D-α-Ala and the same rule was true between DIPP-β-Ala and DIPP-γ-Aba. Meantime, the reaction rate of DIPP-L/D-α-Ala was as 10 times as that of DIPP-β-Ala or DIPP-γ-Aba. Under basic conditions, the hydrolysis reactions of DIPP-β-Ala and DIPP-γ-Aba almost did not take place and the reaction rate of DIPP-L/D-α-Ala was about 1/10 of that under acid conditions. Moreover, theoretical calculation further illuminated the differences of the hydrolysis rate from the view of energy. The results would provide some helpful clues to why nature chose a-amino acids but not other kinds of analogs as protein backbones.     

Construction and Analysis of N-phosphoryl Peptide Libraries

N-Phosphoryl peptide libraries were constructed by transformation from homo-oligopeptide libraries, which was synthesized by self-assembly of amino acids with the assistance of phosphorus oxychloride. Electrospray ionization mass spectrometry (ESI-MS) was used to monitor the reaction.     

Synthesis of N-Phosphoryl Branched Peptides

H-phosphonates were conveniently prepared by direct transesterification of diphenyl phosphite (DPP) with the corresponding alcohols, without further purification they were reacted with branched peptide methyl ester (L-Leu2-L-LysOMe) through Atherton-Todd method, a series of different substituted alkyloxy (N-phosphoryl-L-Leu)2-L-LysOMe were synthesized, and their stmctures were confirmed by ^31P NMR, ESI-MS, ^1H NMR, ^13C NMR, IR and elemental analysis. The approach possesses the advantages of easy operation, high yield and inexpensive phosphorylating reagent.     

HPLC-ESI-MS/MS识别蓝莓提取物中的花青素和黄酮醇

用高效液相色谱-电喷雾离子化串联质谱联用技术(HPLC-ESI-MS/MS)对蓝莓提取物中的黄酮类物质进行了分析, 可以快速地鉴定其主要成分为花青素和黄酮醇. 结构上的不同导致花青素和黄酮醇在紫外-可见光谱吸收、离子化以及裂解方式上都存在差异. 尽管花青素和黄酮醇在270 nm处都有吸收, 但两者分别在530和372 nm附近有特征吸收. 负离子模式下, 黄酮醇可以生成负离子和自由基负离子, 而正离子型的花青素则几乎不产生质谱信号, 这一显著差异可用以区别花青素和黄酮醇. 花青素与黄酮醇在串联质谱中分别拥有各自的特征产物离子更进一步证实了其结构存在差别. 该研究对于蓝莓提取物的质量分析与控制很有帮助.     

HPLC-ESI-MS/MS检测典型废水与活性污泥中4种大环内酯类抗生素

应用超声波辅助萃取技术,联合固相萃取及高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)技术建立了典型废水和活性污泥中4种大环内酯类抗生素(MLs)的高灵敏分析方法。水样经Oasis HLB萃取小柱富集、净化后以甲醇洗脱;活性污泥样品以乙腈-磷酸盐缓冲溶液为溶剂超声萃取、富集、净化。采用HPLC-ESI-MS/MS进行定量分析;流动相为乙腈-乙酸铵水溶液,采用电喷雾正电离源和选择性反应监测模式进行检测。结果表明,4种抗生素的线性范围为0.1～100μg·L-1,相关系数均大于0.99,方法检出限为0.002～0.019 pg,废水和活性污泥样品中MLs的平均回收率分别为70.2%～90.6%和75.6%～88.7%,方法检出限分别为0.013～0.025 ng·L-1和0.09～0.22 ng.g-1。将建立的方法应用于新疆石河子市可能的抗生素污染源典型废水和活性污泥样品中4种MLs的检测,结果表明,MLs普遍存在于各废水(未检出～308.23ng·L-1)和活性污泥(未检出～120.46 ng.g-1)样品中。     

人体结肠癌组织样品中基因组DNA甲基化水平的HPLC—ESI MS／MS检测

利用多重监测反应模式(MRM),通过对液相色谱及质谱条件的优化,建立了人体结肠癌组织样品中基因组DNA甲基化的高效液相色谱-电喷雾质谱(HPLC-ESI MS/MS)检测方法,对结肠癌组织及癌旁组织中基因组DNA甲基化进行了检测.结果表明,5-甲基脱氧胞苷(5mdC)的检出限是1 pg,线性范围为0.037 5～0.5 mg/L,工作曲线相关系数大于0.999 0,该方法的相对标准偏差为2.32%～9.21%.结肠癌病人样品检测结果表明,结肠癌组织基因组DNA甲基化水平低于相应的癌旁组织(P<0.05).     

HPLC-ESI-MS/MS对灯盏花提取液中主要成分的分离定性

本文利用高效液相色谱-电喷雾-质谱／质谱(HPLC—ESI—MS／MS)联用对灯盏花提取液进行了分离,并对其中的主要成分进行了定性分析。一级质谱扫描结果表明,灯盏花提取液中主要有4个峰,其中,第一个峰可能为5,6,4-三羟基黄酮-7-o-β-D-半乳糖醛酸苷,第二峰为灯盏花乙素;后两峰为黄芩甙,两者可能互为同分异构体。     

盐处理下植物组织中甜菜碱和脯氨酸的HPLC-ESI-MS分析

通过高效液相色谱—电喷雾质谱(HPLC—ESI—MS)联用技术,优化了pH、流速、温度、鞘气和辅气等相关影响因素,建立了一个有选择性的、高灵敏度的分析方法,鉴定盐处理下植物组织提取物中的甜菜碱和脯氨酸,一次性快速地分析了甘氨酸甜菜碱、β—丙氨酸甜菜碱、葫芦巴碱、脯氨酸甜菜碱、4—羟脯氨酸甜菜碱和脯氨酸等6种化合物。其标准曲线(50～1000ng／mL)呈直线,线性相关系数大于0.999;相对标准偏差(RSD)为0．5％～15％,回收率在94．0％～97．0％之间。运用这一方法已经分析了大麦、小麦、大豆、甜菜和碱蓬等植物组织中的甜菜碱和脯氨酸,获得了较理想的实验数据,为揭示甜菜碱和脯氨酸与植物的耐盐性生理机制、耐盐品种的鉴定和选育提供了依据。     

HPLC-MS/MS法同时测定果蔬中6种植物生长抑制剂残留

利用高效液相色谱-电喷雾串联质谱(HPLC-ESI MS/MS)技术,建立了果蔬中氯化胆碱、矮壮素、缩节胺、嘧啶醇、多效唑、烯效唑6种植物生长抑制剂残留的检测方法.考察了流动相组分和流动相添加剂对质谱离子化效率的影响以及提取溶剂、提取剂用量和固相萃取柱对萃取效率的影响.在优化条件下,6种目标化合物在1.0 ～200.0...     

Analysis of Hydrolysis Reaction of N-Phosphorylphenylalanine by HPLC-ESI-MS/MS

Hydrolysis procedure of N-diisopropyloxyphosphoryl phenylalanine (DIPP-Phe) has been studied by HPLCESI-MS. The hydrolysis products and intermediate were identified by HPLC-ESI-MS/MS. The results showed that (HO)(i-PrO)P(O)Phe was intermediate in the hydrolysis process.     

Hydrolysis of DNA by N-Phosphoryl Branched Peptide

A N-phosphoryl branched peptide (DIPP-Leu) ₂ -Lys-OCH ₃ was found to efficiently cleave double-strand DNA such as PUC19 and Lambda DNA at pH 8.5 in 100 mM Tris-HCl buffer. The T4 ligase experiment implied that the DNA cleavage occurs via a hydrolytic path.     

利用HPLC-ESI-MS/MS区分黄芩中黄酮C-苷异构体的研究

采用HPLC-ESI-MS/MS联用技术区分了黄芩中两种互为同分异构体的黄酮C-苷类化合物5,7-OH-6-C-阿拉伯糖-8-C-葡萄糖黄酮和5,7-OH-6-C-葡萄糖-8-C-阿拉伯糖黄酮.阐述了黄酮C-苷类化合物同分异构体的电喷雾串联质谱(ESI-MSⁿ)的特征碎裂规律,证明了[M-H-60]^-,[M-H-90]^-及[M-H-120]^-离子是其特征离子.实验结果表明,对于C-6位五碳糖取代和C-8位六碳糖取代的黄酮C-苷二级串联质谱产生的[M-H-60]^-离子(^0,3₅X),其丰度一般大于50%;而对于C-6位六碳糖取代和C-8位五碳糖取代的黄酮C-苷二级串联质谱产生的[M-H-60]^-离子(^0,3₅X),其丰度一般小于50%.据此可区分两种互为同分异构体的黄酮C-苷类化合物.     

Synthesis and Biological Activities of N-Phosphoryl Branched Peptides

Much research has shown that some N-phosphoryl peptides are endowed with important biological activities. For instance, Na-(diaryloxyphosphoryl)-L-alanyl-L-prolines are moderate inhibitors of angiotensin converting enzyme and yield highly potent inhibitors when they hydrolyze under physiological condition lossing 1 mol phenol1; Phosphoramido (N-[(a-rhamnopyranosyloxy)hydroxyphosphinyl]-L-Leu-L-Trp) and its analogues have been shown to be inhibitors of endothelin converting enzyme, therefor…     

Investigation of Aconitine-type Alkaloids from Processed Tuber of Aconitum carmiechaeli by HPLC-ESI-MS/MS~n

Introduction Aconitine-type alkaloids isolated from the roots of Aconitum carmiechaeli show a potential toxicity and a broad spectrum of bioactivity[1-4].On the basis of the C8-substituent of C19-diterpenoid skeleton,aconitine-type alkaloids can be divided into diester-diterpenoid alkaloids(DDAs),monoester-diterpenoid alkaloids(MDAs),and lipo-alkaloids(Fig.1).     

Qualitative and Quantitative Analysis of Alkaloids in Cortex Phellodendri by HPLC-ESI-MS/MS and HPLC-DAD

A combined method of high performance liquid chromatograph-elecrtrospray-ionization mass spectrometer(HPLC-ESI-MS/MS) coupled with a photodiode array detector(HPLC-DAD) and principal component analysis(PCA) was applied to the qualitative and quantitative analyses of alkaloids in Cortex Phellodendri(CP) samples, and to the differentiation of two species of CP, Cortex Phellodendri Chinensis(CPC) and Cortex Phellodendri Amurensis(CPA). Twenty-two peaks appeared in the HPLC-MS base peak chromatogram of CP detec...     

Analysis of Low-polar Ginsenosides in Steamed Panax Ginseng at High-temperature by HPLC-ESI-MS/MS

A high performance liquid chromatography coupled with electrospray ionization-tandem mass spectrometry( HPLC-ESI-MS/MS) method was developed for the analysis and identification of ginsenosides in the extracts of raw Panax ginseng(RPG) and steamed Panax ginseng at high temperatures(SPGHT). A total of 25 ginsenosides were extracted include of which 10 low-polar ginsenosides, such as ginsenosides F4, Rk3, Rh4, 20S-Rg3, 20R-Rg3 and so on, were identified according to their HPLC retention time and MS/MS data. The results indicated that the low polar ginsenosides were seldom found in RPG. For the exploration of the transformation pattern of the ginsenosides in steam processing, the standards of ginsenosides Re, Rg1, Rb1, Rc, Rb2, Rb3 and Rd were selected and hydrolyzed at a temperature of 120 ℃. The results show that these polar ginsenosides can be converted to low-polar ginsenosides such as Rg2, Rg6, F4, Rk3 and Rg5 by hydrolyzing the sugar chains.     

N-磷酰化氨基酸与核糖核苷反应的研究

研究了Ｎ－磷酰化氨基酸与核苷在水溶液中的反应，反应中能够同时生成小肽和小的寡核苷酸；不同的Ｎ－磷酰化氨基酸与不同的核苷之间的反应具有一定的选择性。     

液相色谱串联质谱法用于肌酸的长期毒性研究

肌酸是一种普遍流行的能量增强剂,在生物体内代谢为甲胺,甲胺在对氨基脲敏感的胺氧化酶(semicarbazied-sensitive amine oxidases,SSAO)的催化下进一步生成甲醛、过氧化氢和氨。本文将肌酸的毒性与SSAO活性的升高和产物甲醛的积累联系起来,提出肌酸代谢的毒性假说,建立液相色谱串联离子阱质谱检测SSAO活性的新方法。结果表明,服用肌酸2个月后小鼠尿液中甲胺、甲醛含量升高,血清中SSAO活性升高,对肌酸的长期毒性给于了肯定的评价。