Native Top-Down Mass Spectrometry and Ion Mobility MS for Characterizing the Cobalt and Manganese Metal Binding of α-Synuclein Protein

Wongkongkathep, Piriya,Han, Jong Yoon,Choi, Tae Su,Yin, Sheng,Kim, Hugh I.,Loo, Joseph A. Springer New York LLC 2018 Journal of the American Society for Mass Spectrome Vol.29 No.9

<P>Structural characterization of intrinsically disordered proteins (IDPs) has been a major challenge in the field of protein science due to limited capabilities to obtain full-length high-resolution structures. Native ESI-MS with top-down MS was utilized to obtain structural features of protein-ligand binding for the Parkinson’s disease-related protein, α-synuclein (αSyn), which is natively unstructured. Binding of heavy metals has been implicated in the accelerated formation of αSyn aggregation. Using high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry, native top-down MS with various fragmentation methods, including electron capture dissociation (ECD), collisional activated dissociation (CAD), and multistage tandem MS (MS<SUP>3</SUP>), deduced the binding sites of cobalt and manganese to the C-terminal region of the protein. Ion mobility MS (IM-MS) revealed a collapse toward compacted states of αSyn upon metal binding. The combination of native top-down MS and IM-MS provides structural information of protein-ligand interactions for intrinsically disordered proteins.</P> [FIG OMISSION]</BR>

Effective Application of Bicelles for Conformational Analysis of G Protein-Coupled Receptors by Hydrogen/Deuterium Exchange Mass Spectrometry

Duc, Nguyen Minh,Du, Yang,Thorsen, Thor S.,Lee, Su Youn,Zhang, Cheng,Kato, Hideaki,Kobilka, Brian K.,Chung, Ka Young Springer New York LLC 2015 Journal of the American Society for Mass Spectrome Vol.26 No.5

<P>G protein-coupled receptors (GPCRs) have important roles in physiology and pathology, and 40% of drugs currently on the market target GPCRs for the treatment of various diseases. Because of their therapeutic importance, the structural mechanism of GPCR signaling is of great interest in the field of drug discovery. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a useful tool for analyzing ligand binding sites, the protein-protein interaction interface, and conformational changes of proteins. However, its application to GPCRs has been limited for various reasons, including the hydrophobic nature of GPCRs and the use of detergents in their preparation. In the present study, we tested the application of bicelles as a means of solubilizing GPCRs for HDX-MS studies. GPCRs (e.g., β<SUB>2</SUB>-adrenergic receptor [β<SUB>2</SUB>AR], μ-opioid receptor, and protease-activated receptor 1) solubilized in bicelles produced better sequence coverage (greater than 90%) than GPCRs solubilized in n-dodecyl-β-D-maltopyranoside (DDM), suggesting that bicelles are a more effective method of solubilization for HDX-MS studies. The HDX-MS profile of β<SUB>2</SUB>AR in bicelles showed that transmembrane domains (TMs) undergo lower deuterium uptake than intracellular or extracellular regions, which is consistent with the fact that the TMs are highly ordered and embedded in bicelles. The overall HDX-MS profiles of β<SUB>2</SUB>AR solubilized in bicelles and in DDM were similar except for intracellular loop 3. Interestingly, we detected EX1 kinetics, an important phenomenon in protein dynamics, at the C-terminus of TM6 in β<SUB>2</SUB>AR. In conclusion, we suggest the application of bicelles as a useful method for solubilizing GPCRs for conformational analysis by HDX-MS.</P> [FIG OMISSION]</BR>

Airborne Single Particle Mass Spectrometers (SPLAT II & miniSPLAT) and New Software for Data Visualization and Analysis in a Geo-Spatial Context

Zelenyuk, Alla,Imre, Dan,Wilson, Jacqueline,Zhang, Zhiyuan,Wang, Jun,Mueller, Klaus Springer New York LLC 2015 Journal of the American Society for Mass Spectrome Vol.26 No.2

<P>Understanding the effect of aerosols on climate requires knowledge of the size and chemical composition of <I>individual</I> aerosol particles-two fundamental properties that determine an aerosol’s optical properties and ability to serve as cloud condensation or ice nuclei. Here we present our aircraft-compatible single particle mass spectrometers, SPLAT II and its new, miniaturized version, miniSPLAT that measure in-situ and in real-time the size and chemical composition of individual aerosol particles with extremely high sensitivity, temporal resolution, and sizing precision on the order of a monolayer. Although miniSPLAT’s size, weight, and power consumption are significantly smaller, its performance is on par with SPLAT II. Both instruments operate in dual data acquisition mode to measure, in addition to single particle size and composition, particle number concentrations, size distributions, density, and asphericity with high temporal resolution. We also present ND-Scope, our newly developed interactive visual analytics software package. ND-Scope is designed to explore and visualize the vast amount of complex, multidimensional data acquired by our single particle mass spectrometers, along with other aerosol and cloud characterization instruments on-board aircraft. We demonstrate that ND-Scope makes it possible to visualize the relationships between different observables and to view the data in a geo-spatial context, using the interactive and fully coupled Google Earth and Parallel Coordinates displays. Here we illustrate the utility of ND-Scope to visualize the spatial distribution of atmospheric particles of different compositions, and explore the relationship between individual particle compositions and their activity as cloud condensation nuclei.</P> [FIG OMISSION]</BR>

Local susceptibility causes diffusion alterations in patients with Alzheimer's disease and mild cognitive impairment.

Jahng, Geon-Ho,Xu, Songfan Springer New York LLC 2012 BRAIN IMAGING AND BEHAVIOR Vol.6 No.3

<P>Recent studies with positron emission tomography (PET) using the Pittsburgh compound B (PIB) found widespread amyloid plaque depositions in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI) and even in cognitively normal (CN) subjects. The aim of this study was to investigate whether the local susceptibility gradients in brain tissue alter regional diffusion measurements using MRI in patients with AD and MCI. Two diffusion tensor (DT)-MRI data sets were acquired with alternating polarities of the external diffusion-sensitizing gradients. Three subject groups were included: 15 patients with AD, 18 patients with MCI and 16 CN. Maps of mean diffusivity (MD) and fractional anisotropy (FA) were computed separately for positive (p) and negative (n) polarities (pMD and nMD, pFA and nFA). Voxel-wise paired t-tests were performed between pMD versus nMD or between pFA versus nFA maps, separately for each subject group. We also investigated regions-of-interest (ROIs) in the brain. Based on the pair-wise comparisons, we found significant differences between pMD and nMD in all three groups. Results of ROI-based analyses showed that the non-linear behaviors of the ROI data sets were shown for all three groups. In conclusion, significant differences of MD maps between the two polarities of diffusion-sensitizing gradients were found, suggesting that the intrinsic background gradients may alter MD signals in specific regions. It can be important to take into account the effects of local gradient alterations during diffusion measurements in patients with AD, MCI and elderly controls.</P>

Spectral Reproducibility and Quantification of Peptides in MALDI of Samples Prepared by Micro-Spotting

Bae, Yong Jin,Park, Kyung Man,Ahn, Sung Hee,Moon, Jeong Hee,Kim, Myung Soo Springer New York LLC 2014 Journal of the American Society for Mass Spectrome Vol.25 No.8

<P>Previously, we reported that MALDI spectra of peptides became reproducible when temperature was kept constant. Linear calibration curves derived from such spectral data could be used for quantification. Homogeneity of samples was one of the requirements. Among the three popular matrices used in peptide MALDI [i.e., α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (DHB), and sinapinic acid (SA)], homogeneous samples could be prepared by conventional means only for CHCA. In this work, we showed that sample preparation by micro-spotting improved the homogeneity for all three cases.</P> [FIG OMISSION]</BR>

Application of Phase Correction to Improve the Interpretation of Crude Oil Spectra Obtained Using 7 T Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Cho, Yunju,Qi, Yulin,O’Connor, Peter B.,Barrow, Mark P.,Kim, Sunghwan Springer New York LLC 2014 Journal of the American Society for Mass Spectrome Vol.25 No.1

<P>In this study, a phase-correction technique was applied to the study of crude oil spectra obtained using a 7 T Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). 7 T FT-ICR MS had not been widely used for oil analysis due to the lower resolving power compared with high field FT-ICR MS. For low field instruments, usage of data that has not been phase-corrected results in an inability to resolve critical mass splits of C<SUB>3</SUB> and SH<SUB>4</SUB> (3.4 mDa), and <SUP>13</SUP>C and CH (4.5 mDa). This results in incorrect assignments of molecular formulae, and discontinuous double bond equivalents (DBE) and carbon number distributions of S<SUB>1</SUB>, S<SUB>2</SUB>, and hydrocarbon classes are obtained. Application of phase correction to the same data, however, improves the reliability of assignments and produces continuous DBE and carbon number distributions. Therefore, this study clearly demonstrates that phase correction improves data analysis and the reliability of assignments of molecular formulae in crude oil anlayses.</P> [FIG OMISSION]</BR>

Genetic Improvement of the Fatty Acid Biosynthesis System to Alter the ω-6/ω-3 Ratio in the Soybean Seed

Kulkarni, Krishnanand P.,Kim, Minsu,Song, Jong Tae,Bilyeu, Kristin D.,Lee, Jeong-Dong Springer New York LLC 2017 Journal of the American Oil Chemists' Society Vol. No.

Optimization and Application of APCI Hydrogen-Deuterium Exchange Mass Spectrometry (HDX MS) for the Speciation of Nitrogen Compounds

Acter, Thamina,Cho, Yunju,Kim, Sungji,Ahmed, Arif,Kim, Byungjoo,Kim, Sunghwan Springer New York LLC 2015 Journal of the American Society for Mass Spectrome Vol.26 No.9

<P>A systematic study was performed to investigate the utility of atmospheric pressure chemical ionization hydrogen-deuterium exchange mass spectrometry (APCI HDX MS) to identify the structures of nitrogen-containing aromatic compounds. First, experiments were performed to determine the optimized experimental conditions, with dichloromethane and CH<SUB>3</SUB>OD found to be good cosolvents for APCI HDX. In addition, a positive correlation between the heated capillary temperature and the observed HDX signal was observed, and it was suggested that the HDX reaction occurred when molecules were contained in the solvent cluster. Second, 20 standard nitrogen-containing compounds were analyzed to investigate whether speciation could be determined based on the different types of ions produced from nitrogen-containing compounds with various functional groups. The number of exchanges occurring within the compounds correlated well with the number of active hydrogen atoms attached to nitrogen, and it was confirmed that APCI HDX MS could be used to determine speciation. The results obtained by APCI HDX MS were combined with the subsequent investigation of the double bond equivalence distribution and indicated that resins of shale oil extract contained mostly pyridine type nitrogen compounds. This study confirmed that APCI HDX MS can be added to previously reported chemical ionization, electrospray ionization, and atmospheric pressure photo ionization-based HDX methods, which can be used for structural elucidation by mass spectrometry.</P> [FIG OMISSION]</BR>

Distinct Fragmentation Pathways of Anticancer Drugs Induced by Charge-Carrying Cations in the Gas Phase

Hong, Areum,Lee, Hong Hee,Heo, Chae Eun,Cho, Yunju,Kim, Sunghwan,Kang, Dukjin,Kim, Hugh I. Springer New York LLC 2017 Journal of the American Society for Mass Spectrome Vol.28 No.4

<P>With the growth of the pharmaceutical industry, structural elucidation of drugs and derivatives using tandem mass spectrometry (MS<SUP>2</SUP>) has become essential for drug development and pharmacokinetics studies because of its high sensitivity and low sample requirement. Thus, research seeking to understand fundamental relationships between fragmentation patterns and precursor ion structures in the gas phase has gained attention. In this study, we investigate the fragmentation of the widely used anticancer drugs, doxorubicin (DOX), vinblastine (VBL), and vinorelbine (VRL), complexed by a singly charged proton or alkali metal ion (Li<SUP>+</SUP>, Na<SUP>+</SUP>, K<SUP>+</SUP>) in the gas phase. The drug-cation complexes exhibit distinct fragmentation patterns in tandem mass spectra as a function of cation size. The trends in fragmentation patterns are explicable in terms of structures derived from ion mobility mass spectrometry (IM-MS) and theoretical calculations.</P> [FIG OMISSION]</BR>

Lipase-Mediated Synthesis of Fatty Acid Esters Using a Blending Alcohol Consisting of Methanol and 1-Butanol

Zhao, TingTing,Choi, Nakyung,Kim, Heejin,Kim, Yangha,Kim, Hak-Ryul,Kim, In-Hwan Springer New York LLC 2017 Journal of the American Oil Chemists' Society Vol. No.

<P>Lipase-mediated transesterification of soybean oil with a blending alcohol consisting of methanol and 1-butanol for synthesis of fatty acid esters was carried out. Lipase from Thermomyces lanuginosa (Lipozyme TL IM) was used as a biocatalyst. The lipase was purchased from Novozymes (Seoul, Republic of Korea). The effects of the molar proportions of methanol and 1-butanol in the blending alcohol, reaction temperature, enzyme loading and water content were investigated, for reaction optimization. The relative consuming rates of methanol and 1-butanol during the reaction were also explored. Among seven different ratios of alcohol blends employed in this study, that containing 80 mol% methanol gave the highest yield of fatty acid esters. Optimum reaction temperature, enzyme loading, and water content were 30 A degrees C, 15% (based on the substrate weight), and 0.3% (based on the substrate weight), respectively. Water influenced significantly the reaction rate and yield. On the transesterification, the degree of reaction of methanol was higher than that of 1-butanol and the presence of 1-butanol contributed to increase of the reaction rate as well as yield. The maximum yield of ca. 98 wt% was achieved under the optimized condition.</P>