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1.
Cooper TJ Talaty ER Van Stipdonk MJ 《Journal of the American Society for Mass Spectrometry》2005,16(8):1305-1310
We report a new fragmentation pathway for the CID of (b3 - 1 + Cat)+ product ions derived from the model peptide AXAG, where X = beta-alanine, gamma-aminobutyric acid, epsilon-amino-n-caproic acid, or 4-aminomethylbenzoic acid. By changing the amino acid to the C-terminal side of the amino acid X, and incorporating 15N and 13C labeled residues at the same position, we conclude that the dissociation pathway most likely leads to a metal cationized nitrile. With respect to the various amino acids at position X, the putative nitrile product becomes more prominent, relative to the conventional (a3 - 1 + Cat)+ species, in the order beta-alanine < gamma-aminobutyric acid < epsilon-aminocaproic acid < 4-aminomethylbenzoic acid. The pathway is not observed for peptides with alpha-amino acids at position X. The product ion is observed most prominently during the CID of Li+ and Na+ cationized peptides, only to a small extent for Ag+ cationized peptides, and not at all from protonated analogues. 相似文献
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Gologan B Takáts Z Alvarez J Wiseman JM Talaty N Ouyang Z Cooks RG 《Journal of the American Society for Mass Spectrometry》2004,15(12):1874-1884
Protein ions, after mass spectrometric separation, can be soft-landed into liquid surfaces with preservation of their native structures. Retention of biological activity is strongly favored in glycerol-based surfaces but not in self-assembled monolayer solid surfaces. Soft-landing efficiency for multiply-charged hexokinase ions was found to be some four times higher for a glycerol/fructose liquid surface than for a fluorinated self-assembled monolayer surface. Soft-landing into liquid surfaces is also shown to allow (1) protein purification, (2) on-surface identification of the soft-landed material using MALDI, and (3) protein identification by in-surface tryptic digestion. Pure lysozyme was successfully isolated from different mixtures including an oxidized, partially decomposed batch of the protein and a partial tryptic digest. Liquid glycerol/carbohydrate mixtures could be used directly to record MALDI spectra on the soft-landed compounds provided they were fortified in advance with traditional MALDI matrices such as p-nitroaniline and alpha-cyano-4-hydroxycinnamic acid. Various proteins were soft-landed and detected on-target using these types of liquid surface. Soft-landing of multiply-charged lysozyme ions onto fluorinated self-assembled monolayer surfaces was found to occur with a limited amount of neutralization, and trapped multiply-charged ions could be desorbed from the surface by laser desorption. Initial data is shown for a new approach to protein identification that combines top-down and bottom-up approaches by utilizing protein ion soft-landing from a protein mixture, followed by tryptic digestion of the landed material and detection of characteristic tryptic fragments by MALDI. 相似文献
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Chen X Nam SW Kim GH Song N Jeong Y Shin I Kim SK Kim J Park S Yoon J 《Chemical communications (Cambridge, England)》2010,46(47):8953-8955
A new NIR fluorescent sensor based on an amine-substituted heptamethine cyanine dye displayed a highly selective fluorescence enhancement with cyanide in aqueous solutions, and was applied for the imaging of anthropogenic and biogenic cyanide. 相似文献
5.
Joseph H. Reibenspies Erach R. Talaty Mashitah M. Yusoff 《Journal of chemical crystallography》1997,27(12):727-730
The crystal and molecular structure of (RS)-N-Tert-butyl-2-anilino-3,3-dimethylbutanamide, a derivative of an amino acid that was obtained by highly selective cleavage of 1,3-di-tert-butylaziridinone by aniline, is described. The racemic mixture of the amide crystallizes in the space groupP 21/n with four molecules per unit cell. Crystal Data:a=10.483(2) Å,b=6.206(1) Å,c=24.767(5) Å,β=90.39(3),V=1611.5(6) A3,R(F)[I>2σ(I)]=0.0679.wR(F 2) [I>2σ(I)]=0.1148. 相似文献
6.
Dae San Kim Nari Lee Kyoung Ho Park 《Journal of Mathematical Analysis and Applications》2011,379(1):388-400
We derive twenty five basic identities of symmetry in three variables related to higher-order Euler polynomials and alternating power sums. This demonstrates that there are abundant identities of symmetry in three-variable case, in contrast to two-variable case, where there are only a few. These are all new, since there have been results only about identities of symmetry in two variables. The derivations of identities are based on the p-adic integral expression of the generating function for the higher-order Euler polynomials and the quotient of integrals that can be expressed as the exponential generating function for the alternating power sums. 相似文献
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In this paper, we study an elliptic equation arising from the self-dual Maxwell gauged sigma model coupled with gravity. When the parameter τ equals 1 and there is only one singular source, we consider radially symmetric solutions. There appear three important constants: a positive parameter a representing a scaled gravitational constant, a nonnegative integer representing the total string number, and a nonnegative integer representing the total anti-string number. The values of the products play a crucial role in classifying radial solutions. By using the decay rates of solutions at infinity, we provide a complete classification of solutions for all possible values of and . This improves previously known results. 相似文献
8.
Principal component analysis of urine metabolites detected by NMR and DESI–MS in patients with inborn errors of metabolism 总被引:1,自引:0,他引:1
Pan Z Gu H Talaty N Chen H Shanaiah N Hainline BE Cooks RG Raftery D 《Analytical and bioanalytical chemistry》2007,387(2):539-549
Urine metabolic profiles of patients with inborn errors of metabolism were examined with nuclear magnetic resonance (NMR) and desorption electrospray ionization mass spectrometry (DESI-MS) methods. Spectra obtained from the study of urine samples from individual patients with argininosuccinic aciduria (ASA), classic homocystinuria (HCY), classic methylmalonic acidemia (MMA), maple syrup urine disease (MSUD), phenylketonuria (PKU) and type II tyrosinemia (TYRO) were compared with six control patient urine samples using principal component analysis (PCA). Target molecule spectra were identified from the loading plots of PCA output and compared with known metabolic profiles from the literature and metabolite databases. Results obtained from the two techniques were then correlated to obtain a common list of molecules associated with the different diseases and metabolic pathways. The combined approach discussed here may prove useful in the rapid screening of biological fluids from sick patients and may help to improve the understanding of these rare diseases. 相似文献
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Justes DR Talaty N Cotte-Rodriguez I Cooks RG 《Chemical communications (Cambridge, England)》2007,(21):2142-2144
Single nanogram amounts of the explosives TNT, RDX, HMX, PETN and their mixtures were detected and identified in a few seconds on the surface of human skin without any sample preparation by desorption electrospray ionization (DESI) using a spray solution of methanol-water doped with sodium chloride to form the chloride adducts with RDX, HMX, and PETN while TNT was examined as the radical anion and tandem mass spectrometry was used to confirm the identifications. 相似文献
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Nari N. Talaty Kristina Beck Helene Citeau Kristin Kirschbaum Dean M. Giolando Prof. Dr. 《无机化学与普通化学杂志》2009,635(1):53-63
A new single‐source precursor, [SnCl4{OC(H)OC2H5}2], prepared by treating tin tetrachloride with ethyl formate (1:2 ratio) was developed for the deposition of tin oxide thin films on glass substrates. The compound [SnCl4{OC(H)OC2H5}2] is highly volatile and provides very high growth rates (up to 100Å s?1 at 560 °C) in an atmospheric pressure chemical vapor deposition (APCVD) reactor. More significantly, the compound does not decompose to tin oxide below 320 °C, thereby minimizing the formation of particles in the vapor above the growing tin oxide film. To prepare highly conducting fluorine doped tin oxide (SnO2:F) films 2,2,2‐trifluoroethyl trifluoroacetate was used as the source of fluoride. High quality SnO2:F films were deposited at 560 °C with a flow rate of 2 mL fluoride reagent hr?1; typical film properties are resistivity of 5.9 X 10?4 Ω cm, Hall mobility of 27.3 cm2 V?1 s?1, carrier concentration of 3.9 X 1020 cm?3 and percent transmission ranging from 86 to 88 %. The best films of SnO2:F possess transparencies as high as 90 % (750 nm), sheet resistances as low as 7 Ω sq?1 and Haacke's figure of merit as high as 29 X 10?3 (750 nm). The newly developed APCVD reactor and the chemistry were optimized with respect to structural, electrical and optical properties of the films by adjusting the substrate temperature, gas flow rates and the amount of fluoride present in the vapor stream. Growth rates with respect to deposition time, substrate temperature and flow rates of precursors were found to be similar for both undoped (SnO2) and doped (SnO2:F) samples. The SnO2:F films possess larger grains than the SnO2 which may account for the lower resistivity and the higher mobility in the SnO2:F samples. 相似文献