• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1221-1227
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• 2011

Ethyl pyruvate (EP) is known as a scavenger of reactive oxygen species (ROS) in the body through its role in the donation of diketone groups to metals to form an EP-metal complex. In order to develop a method for the quantification of EP in biological media, a sensitive and specific, high-performance liquid chromatographyelectrospray ionization-mass spectrometry (HPLC-ESI/MS) method is used to determine the EP-alkali metal ion binding species. The analyte was separated on a ZORBOX SB-C8 ($3.5{\mu}m$, $30mm{\times}2.1mm$ I.D.) column and analyzed in selected ion monitoring (SIM) mode with a positive ESI interface using the m/z 255 $[2M + Na]^+$ ion. The method was validated over the concentration range of $0.5-60.0\;{\mu}g$/mL under 1/9 (v/v) of acetonitrile/methanol solvent system with flow rate 0.05 mL/min. The limit of quantification (LOQ) was $0.5{\mu}g$/mL.

• Mass Spectrometry Letters
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• 제12권4호
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• pp.137-145
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• 2021

Herein we report multiple ion mobility (IM) peaks in electrospray ionization IM mass spectrometry (ESI-IM-MS) produced by glutamine residue in peptide. The mobility features of 147 peptides were investigated using ESI-IM-MS combined with liquid chromatography. Of these peptides, 66 presented multiple IM peaks, and analysis of their sequence using collision induced dissociation (CID) revealed that glutamine (Gln), as well as proline (Pro), plays a critical role in generating multiple IM peaks. Mutant-based investigations using Gln-containing peptides indicate that the side chain of Gln promotes intermolecular interactions, inducing multiple structures of the peptide ions in the gas phase. Consequently, the present study demonstrates that the distinct ion mobility signatures identified herein can potentially be used to characterize glutamine-containing peptide ions.

• Mass Spectrometry Letters
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• 제6권4호
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• pp.99-104
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• 2015

A liquid chromatography mass spectrometry (LC-MS) system was used to identify and distinguish oligostilbene diastereoisomers. A polyphenolic extract from Neobalanocarpus heimii known to be rich in oligostilbenes of various degrees of condensation was used as test material. Fourteen oligostilbenes were isolated from this extract on a fully automated semi-preparative HPLC system. Out of these, two pairs of dimers, one pair of trimers, two pairs of tetramers and a group of four tetramers with similar skeleton were identified as diastereoisomers. Their structures and configurations were established by spectroscopic methods. All isolated compounds were subjected to an LC-MS/MS to study their fragmentation patterns. The experiments were performed on a liquid chromatography-mass spectrometry (LC-MS) with electrospray-ionization (ESI) interface in positive mode. MS/MS spectra of each pure compound were recorded by direct infusion in identical conditions and their product ion spectra were analysed. Some subtle yet significant differences were observed between the spectra of oligostilbenes from the various diastereoisomeric series.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1791-1800
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• 2004

Angiotensin I, a model decapeptide, was glycosylated and partially hydrolyzed with HCl (6 N, 80 $^{\circ}C$, 4 h), aminopeptidase, and carboxypeptidase Y. A single peptide mass map obtained from truncated peptides in the partial acid hydrolysate of angiotensin and its glycosylation product mixture by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry enabled sequencing of angiotensin by a combinatorial procedure. MALDI-TOF and electrospray ionization (ESI) tandem mass spectrometric results indicate that both the N-terminal amino group of aspartic acid and the guanidinium group of the second residue arginine are glycosylated.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3151-3155
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• 2010

This study was performed to develop analytical methods to better understand the properties and reactivity of petroleum, which is a highly complex organic mixture, using high-resolution mass spectrometry and statistical analysis. Ten crude oil samples were analyzed using negative-mode electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Clustering methods, including principle component analysis (PCA), hierarchical clustering analysis (HCA), and k-means clustering, were used to comparatively interpret the spectra. All the methods were consistent and showed that oxygen and sulfur-containing heteroatom species played important roles in clustering samples or peaks. The oxygen-containing samples had higher acidity than the other samples, and the clustering results were linked to properties of the crude oils. This study demonstrated that clustering methods provide a simple and effective way to interpret complex petroleomic data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1534-1535
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• 2007

This paper describes a novel microfluidic device with a microfabricated electrospray source for a sheathless electrospray ionization interface to a mass spectrometer. This electrospray ionization-mass spectrometry (ESI-MS) device consists of a triangular-shaped metal emitter, allowing the generation of an efficient electrospray for peptide detection, and microfluidic channels monolithically in a glass microchip. The performance of the proposed interface was evaluated by opimizing its experimental condition and spraying standard peptides. The spraying has high signal strength and stability, with a relative standard deviation of 2.9% and singly-charged and doubly-charged peaks of the peptides were successfully detected. The metal emitter source showed a good performance to be comparable to commercially available emitters in signal strength and stability.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1339-1342
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• 2010

$^{31}P$ NMR and ESI-MS studies of $Cu^{2+}$ binding to Fenitrothion (FN) were performed by experimentally and theoretically. The calculated $^{31}P$ NMR chemical shifts for FN-$Cu^{2+}$ complexes are in good agreement with experimental chemical shifts in order, and the results present an important information for organophosphorus pesticide metal complexes. ESI-MS and low energy CID MS/MS experiments of FN-$Cu^{2+}$ complexes combined with accurate mass measurements give insight into the metal localization and allow unambiguous identification of fragments and hydrolysis products.

• Mass Spectrometry Letters
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• 제6권1호
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• pp.13-16
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• 2015

This study demonstrated the stabilizing role of a cyclodextrin on Keggin $[PW_{12}O_{40}]^{3-}$ via hydrogen bonding complexation unveiled by ESI-MS. The distinctive fragmentation pathways of the $\{PW_{12}\}/{\gamma}$-CD complexes from that of discrete $[PW_{12}O_{40}]^{3-}$ showed that the so-called "weak" non-covalent interactions can effectively change the dissociation chemistry of POM in the gas phase. The influence of different types of solvents and organic additives such as ${\gamma}$-CD on the stability of Keggin $[PW_{12}O_{40}]^{3-}$ was also addressed firstly by ESI-MS.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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• pp.290.1-290.1
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• 2003

Oxidative DNA damage has been associated with many disease. Quantation of DNA adducts is considered to be a useful biomarker of oxidative DNA damage because its formation can also be induced by oxidative stress. Extensive efforts have been taken to identify the analytical methods for minimizing the artifactual formation of oxidative DNA damage. We have done direct analysis of DNA adducts using LC/ESI-MS without urine sample extraction. (omitted)

• Mass Spectrometry Letters
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• 제12권4호
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• pp.179-185
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• 2021

Collision-induced dissociation (CID) combined with electrospray ionization mass spectrometry (ESI-MS) was used to obtain structural information on rat islet amyloid polypeptide (rIAPP) monomers (M) and dimers (D) observed in the multiply charged state in the MS spectrum. MS/MS analysis indicated that the rIAPP monomers adopt distinct structures depending on the molecular ion charge state. Peptide bond dissociation between L₂₇ and P₂₈ was observed in the MS/MS spectra of rIAPP monomers, regardless of the monomer molecular ion charge state. MS/MS analysis of the dimers indicated that D⁵⁺ comprised M²⁺ and M³⁺ subunits, and that the peptide bond dissociation process between the L₂₇ and P₂₈ residues of the monomer subunit was also maintained. The observation of (M+ b₂₇)⁴⁺ and (M+ y₁₀)³⁺ fragment ions were deduced to originate from the two different D⁵⁺ complex geometries, the N-terminal and C-terminal interaction geometries, respectively. The fragmentation pattern of the [M_rIAPP + M_hIAPP]⁵⁺ MS/MS spectrum showed that the interaction occurred between the two N-terminal regions of M_rIAPP and M_hIAPP in the heterogeneous dimer (hetero-dimer) D⁵⁺ structure.