Unimlecular Depurination of Substituted Deoxyadenosines by Fast Atom Bombardment Mass Spectrometry/Mass Spectrometry

Abstract

The effect of benzoyl substitution on the unimolecular depurination of deoxyadenosine, in the gas-phase, has been evaluated. The glycosidic bond dissociation of the conjugated acids and bases of the isomeric species occurs remote fran the charge sites.     

Fast Atom Bombardment and Tandem Mass Spectrometry for the Identification of Nucleoside Adducts with Phenyl Glycidyl Ether

Abstract

The present study deals with the use of fast atom bombardment (FAB) in combination with constant neutral loss (CNL) scanning, high resolution mass spectrometry and tandem mass spectrometry (MS-MS) with collisionally activated decomposition (CAD), as complementary methods for the identification and structural analysis of phenyl glycidyl ether-nucleoside adducts. Selective detection of the parent ions of the modified nucleosides at the 1–10 ng level has been achieved by suitably designed CNL scans. The elemental composition of the adducts has been determined by accurate mass measurements. CAD-MS has been carried out on the [M + H]⁺ and [M - H]^? ions to derive structural data on the size and nature of the base, sugar and alkyl substituent. In some cases, information on the alkylation site has been obtained, which is very useful for distinguishing isomeric adducts.     

Qualitative and Quantitative Analysis of Cyclic Nucleotides and Related Enzymes by Static and Dynamic Fast Atom Bombardment Mass Spectrometry

Abstract

Fast atom bombardment mass spectrometry in concert with collisionally-induced dissociation and mass-analysed kinetic energy spectrum scanning has enabled unequivocal identification of putative cyclic nucleotides in tissue extracts; quantitative analyses have enabled kinetic studies of cyclic nucleotide-related enzymes with multi-component monitoring, and dynamic spectrometric systems provide a potential means of continuous assay for these enzymes.     

Determination of Betaines by Fast Atom Bombardment Mass Spectrometry : Identification of Glycine Betaine Deficient Genotypes of Zea mays

A rapid, sensitive, and selective method for the determination of betaines is described and discussed. The method entails derivatizing the quaternary ammonium compounds to increase their sensitivity to detection by fast atom bombardment mass spectrometry. Sensitivity of detection increases markedly as the length of the carbon chain of the alcohol used to esterify the betaine carboxylic acid group is increased (C4 > C3 > C2 > C1 > C0). The lower limit of detection of glycine betaine as the n-propyl ester is 0.05 nanomole per microliter of glycerol. Betaine aldehyde can be readily derivatized to the di-n-butyl or di-n-propyl acetal derivatives which exhibit lower limits of detection of about 5 picomoles and 10 picomoles per microliter of glycerol, respectively. Accurate quantification of these compounds is accomplished by the use of deuterium labeled internal standards or quaternary ammonium compound homologs of distinct mass. Methods for the synthesis of these internal standards are reported. Some applications of these methods are illustrated with stable isotope tracer studies on the kinetics of metabolism of choline to betaine aldehyde and glycine betaine in spinach leaf discs, and the identification of several Zea mays genotypes which appear deficient in glycine betaine. Tracer studies with deuterium labeled betaine aldehyde suggest that the deficiency of glycine betaine in one sweet corn hybrid is probably not due to a deficiency in the capacity to oxidize betaine aldehyde.     

Fast atom Bombardment Mass Spectrometry of Nucleosides,Nucleotides and Oligonucleotides

Abstract

Fast atom bombardment (FAB) mass spectrometry, a new ionization technique, has been applied to a variety of polar, nonvolatile compounds with considerable success. Current literature regarding the analysis of nucleosides, nucleotides and oligonucleotides using FAB is reviewed.     

Characterization of polar lipids of oral isolates of Candida, Pichia and Saccharomyces by Fast Atom Bombardment Mass Spectrometry (FAB MS)

AIMS: To characterize fatty acid and phospholipid analogue profiles of oral yeasts. METHODS AND RESULTS: Twenty-seven strains of oral yeasts were cultured on SDA and lipids of freeze-dried cells were extracted and analysed by FAB MS. The most abundant carboxylate anion was m/z 281 (C18 : 1). The most intense phospholipid analogue ions were of PE, PG, PA and PI. Pichia etchellsii contained molecular species of PG and PE, whereas Saccharomyces cerevisiae had PA, PG and PE analogues. Mass spectra revealed that S. cerevisiae and Candida glabrata were distinct from one another and from the other species tested. CONCLUSION: Oral yeasts largely differ with respect to their polar lipids. It is concluded that oral yeast species have distinctive fatty acid and phospholipid analogue anion profiles. SIGNIFICANCE AND IMPACT OF THE STUDY: FAB MS provided novel chemotaxonomic information.     

基于串联质谱的鱼皮明胶鉴别研究

在胶原蛋白序列比对基础上,以虹鳟鱼明胶、猪明胶和牛明胶为模型,利用高效液相色谱－串联质谱技术（HPLC-MS/MS）研究了3种明胶降解多肽组成的差异。使用胰蛋白酶将鱼皮明胶进行了酶解处理,使用HPLC-MS/MS对酶解产物中的多肽组成进行了分析,并与猪和牛明胶酶解产物中的多肽进行了比较。结果表明鱼明胶酶解产物中存在特征多肽,通过特征多肽的种类可区别鱼明胶与猪和牛明胶,研究了明胶多肽中脯氨酸羟基化修饰、明胶分子量范围和脱酰胺化对特征多肽识别的影响。研究表明利用HPLC-MS/MS技术通过识别明胶酶解产物中的特征多肽进行鱼皮明胶鉴别具有可行性。     

Fast Atom Bombardment-High Field Magnet Mass Spectrometry of 6000 Dalton polypeptides

Using a combination of Fast Atom Bombardment lonisation and High Field Magnet — Mass Spectrometry we demonstrate here the ability to observe, for the first time, the accurate molecular weights of polypeptides or other important bioorganic substances up to 6000 Dalton in size. This claim is substantiated with data on intact unreduced Insulin and on the intact sweet protein Monellin, which consists of three polypeptide chains.     

Analysis of the Primary Sequence of Human Myelin Basic Protein Peptides 1–44 and 90–170 by Fast Atom Bombardment Mass Spectrometry

The originally described sequence of human myelin basic protein peptide 45-89 has recently been shown to contain two errors which have now been resolved. In the present study fast atom bombardment mass spectrometry was utilized to analyze the primary sequence of the other portions, peptides 1-44 and 90-170 of human myelin basic protein. The results obtained confirm the accuracy of the primary sequence published for both of these terminal peptides.     

快原子轰击质谱技术结合酶学方法鉴定黑曲霉1,6—缩水—β—D—吡喃葡萄糖激酶的诱导合成

1,6－缩水－β－D－吡喃葡萄糖是纤维素类物质热解的主要产物,黑曲霉突变株CBX－209能较好地利用该糖作为唯一的碳源和能源生长并产生有用的代谢产物柠檬酸,其效率与利用葡萄糖大致相当。利用葡萄糖氧化酶和竦根过氧化物酶复合系统测定证明该菌株不存在1,6－缩水－β－D－吡喃葡萄糖水解酶,采用快原子轰击质谱技术结合6－磷酸葡萄糖脱氢酶系统进行测定,结果表明经（NH4）2SO4沉淀或阴离子交换层析析处理后的无细胞提取液在加入ATP和Mg^2 条件下能直接催化1,6－缩水－β－D－吡喃葡萄糖合成6－磷酸葡萄糖,证明黑曲霉突变株中存在一个新酶,即1,6－缩水－β－D－吡喃葡萄糖激酶。该酶为诱导酶。     

快原子轰击质谱技术结合酶学方法鉴定黑曲霉1,6-缩水-β-D-吡喃葡萄糖激酶的诱导合成

1,6-缩水-β-D-吡喃葡萄糖是纤维素类物质热解的主要产物,黑曲霉突变株CBX209能较好地利用该糖作为唯一的碳源和能源生长并产生有用的代谢产物柠檬酸,其效率与利用葡萄糖大致相当。利用葡萄糖氧化酶和辣根过氧化物酶复合系统测定证明该菌株不存在1,6-缩水-β-D-吡喃葡萄糖水解酶。采用快原子轰击质谱技术结合6磷酸葡萄糖脱氢酶系统进行测定,结果表明经(NH₄)₂SO₄沉淀或阴离子交换层析处理后的无细胞提取液在加入ATP和Mg²⁺的条件下能直接催化1,6-缩水-β-D-吡喃葡萄糖合成6-磷酸葡萄糖,证明黑曲霉突变株中存在一个新酶,即1,6-缩水-β-D-吡喃葡萄糖激酶。该酶为诱导酶。     

A Comparative Study on Structural Elucidation of Sialyl Oligosaccharides by Mass Spectrometry with Fast Atom Bombardment,Electrospray Ionization,and Matrix Assisted Laser Desorption/Ionization

To establish a new protocol for sensitive detection and structural characterization of sialyl oligosaccharides, their sensitivities and structural information from mass spectrometry and tandem mass spectrometry with FAB-, ESI-, and MALDI were evaluated in detail. Among these ionization methods, FAB-MS and FAB-MS/MS gave reproducible and predictable spectra carrying information on sequence and branching of sialyl oligosaccharides after derivatization with 2-aminopyridine (PA). With both positive and negative ion modes, their structural elucidation promises to be straightforward, MS/MS specta being measurable at as low as 200 pmol. Thus, this method consitutes a powerful tool for sensitive detection and structural characterization of limited quantities of sialyl oligosaccharides by FAB-MS and FAB-MS/MS.     

Structural Analysis of New Syringopeptins by Tandem Mass Spectrometry

New syringopeptins SP(SC)-t and -2 were isolated from culture filtrates of phytopathogenic bacterium strain SCt of Pseudomonas syringae pv. syringae. These syringopeptins were composed of a β-hydroxy fatty acid, a long sequence of aliphatic amino acids, and a lactone moiety of eight amino acids. The amino acid sequences were deduced from a comparison of their tandem mass sepctra with those of known syringopeptins SP-22a and SP-25a. SP(SC)-l and SP(SC)-2 resembled SP-22a, but differed from the latter by 3 amino acids.     

Structural Elucidation of Rotihibin B by Tandem Mass Spectrometry

The mutagenicity and desmutagenicity of extracts of soybeans heated at 225 ± 5°C were investigated by the Ames test. The soybeans were refluxed in water, methanol, or diethylether for 2h. The aqueous and methanol extracts (2–4 mg/plate) of the heated soybeans exhibited strong desmutagenic activity of 43–92% against heterocyclic amines (Trp-P-1, Glu-P-2, IQ, MeIQx, PhIP), while no mutagenicity was observed. The desmutagenicity of the heated soybean extracts remained even after denaturation by 0.1 N HCI in vitro and absorption by the rat small intestine. The desmutagenic mechanism for heated soybeans was evaluated, and it was verified that the soybean extract exhibited its desmutagenicity by blocking the mutagenicity of activated Trp-P-1, and not by inhibiting the S9 enzyme system.     

Direct Analysis of Protein Mixtures by Tandem Mass Spectrometry

Methods to identify proteins contained in mixtures are described. The approach uses microcolumn liquid chromatography and automated tandem mass spectrometry in conjunction with protein and nucleotide database searching algorithms. This approach is applied to the identification of proteins obtained by immunoprecipitation reactions, interaction with a GST protein fusion products and interaction with a macromolecular complex.     

C Isotopomer Analysis of Glutamate by Tandem Mass Spectrometry

Tandem mass spectrometry allows a compound to be isolated from the rest of the sample and dissociated into smaller fragments. We show here that fragmentation of glutamate mass isotopomers yields additional mass spectral data that significantly improve the analysis of metabolic fluxes compared to full-scan mass spectrometry. In order to validate the technique, tandem and full-scan mass spectrometry were used along with (13)C NMR to analyze glutamate from rat hearts perfused with three substrate mixtures (5 mM glucose plus 5 mM [2-(13)C]acetate, 5 mM [1-(13)C]glucose plus 5 U/L insulin, and 5 mM glucose plus 1 mM [3-(13)C]pyruvate). Analysis by tandem mass spectrometry showed that the enriched substrate contributed 98 +/- 2, 53 +/- 2, and 84 +/- 7%, respectively, of acetyl-coenzyme A while the rate of anaplerotic substrate entry was 7 +/- 3, 25 +/- 8, and 16 +/- 8%. Similar results were obtained with (13)C NMR data, while values from full-scan data had higher error. We believe that this is the first use of tandem mass spectrometry to determine pathway flux using (13)C-enriched substrates. Although analysis of the citric acid cycle by NMR is simpler (and more intuitive), tandem mass spectrometry has the potential to combine high sensitivity with the high information yield previously available only by NMR.     

Structural Characterization of Carbohydrates by Fourier Transform Tandem Mass Spectrometry

Fourier transform tandem mass spectrometry (MS/MS) provides high mass accuracy, high sensitivity, and analytical versatility and has therefore emerged as an indispensable tool for structural elucidation of biomolecules. Glycosylation is one of the most common posttranslational modifications, occurring in ~50% of proteins. However, due to the structural diversity of carbohydrates, arising from non-template driven biosynthesis, achievement of detailed structural insight is highly challenging. This review briefly discusses carbohydrate sample preparation and ionization methods, and highlights recent developments in alternative high-resolution MS/MS strategies, including infrared multiphoton dissociation (IRMPD), electron capture dissociation (ECD), and electron detachment dissociation (EDD), for carbohydrates with a focus on glycans and proteoglycans from mammalian glycoproteins.     

Synthesis of Purine and Pyrimidine Trihydroxyacyclonucleosides

Abstract

The [[3-hydroxy-2-bis(hydroxymethyl)-l-propoxy]methyl] derivatives of adenine, guanine, cytosine and thymine have been synthesized and tested against herpesviruses.     

毛细管区带电泳／串联质谱联用法鉴定多肽和蛋白质

建立了毛细管区带电泳－串联质谱联用（ＣＺＥ／ＭＳ／ＭＳ）对多肽和蛋白质高灵敏度鉴定方法,对Ｍｅｔ－脑啡肽和Ｌｅｕ－脑啡肽的混合物进行了分析,用ＣＺＥ／ＭＳ／ＭＳ方法验证了各自的序列,同样对细胞色素ｃ的胰蛋白酶酶解产物用ＣＺＥ／ＭＳ／ＭＳ方法进行了肽质谱分析,几科所有肽段的序列及其与在分子中的位置都得到了确定,通过ＳＥＱＵＥＳＴ软件进行蛋白质序列数据库搜索得到准确的鉴定结果,所消耗的样品量均在低皮可     

用于串联质谱鉴定多肽的计量方法

目前已有多种对串联质谱与数据库中多肽的理论质谱的一致性进行评估的高通量计量算法用于鸟枪法蛋白质组学 (shotgunproteomics)研究。然而这些方法操作时存在大量错误的多肽鉴定。这里提出一种新的串联质谱识别多肽序列的计量算法。该算法综合考虑了串联质谱中不同离子出现的概率、多肽的酶切位点数、理论离子与实验离子的匹配程度和匹配模式。对大容量的串联质谱数据集的测试表明 ,根据算法开发的软件PepSearch比目前最常用的软件SEQUEST有更好的鉴定准确性。PepSearch可从http : compbio.sibsnet.org projects pepsearch下载。