Probing High-order Protein Complexes Using Native Mass Spectrometry and Hydrogen/Deuterium Exchange Mass Spectrometry: A Case Study Using Fresh and Commercial Hemoglobin Samples.

Native mass spectrometry (MS) analysis of protein complexes is highly susceptible to matrix effect, and addressing this predicament using buffer exchange is a common approach. Nevertheless, optimization of the buffer exchange protocol is not trivial. With the use of hemoglobin (Hb) as the model entity, it was discovered that the native mass spectrum of protein assembly is highly dependent on the buffer-exchange protocol.

A millimeter water-in-oil droplet as an alternative back exchange prevention strategy for hydrogen/deuterium exchange mass spectrometry of peptides/proteins.

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a versatile bioanalytical technique for protein analysis. Since the reliability of HDX-MS analysis considerably depends on the retention of deuterium labels in the post-labeling workflow, deuterium/hydrogen (D/H) back exchange prevention strategies, including decreasing the pH, temperature, and exposure time to protic sources of the deuterated samples, are widely adopted in the conventional HDX-MS protocol. Herein, an alternative and effective back exchange prevention strategy based on the encapsulation of a millimeter droplet of a labeled peptide solution in a water-immiscible organic solvent (cyclohexane) is proposed.

Determining the gas-phase structures of α-helical peptides from shape, microsolvation, and intramolecular distance data.

Mass spectrometry is a powerful technique for the structural and functional characterization of biomolecules. However, it remains challenging to accurately gauge the gas-phase structure of biomolecular ions and assess to what extent native-like structures are maintained. Here we propose a synergistic approach which utilizes Förster resonance energy transfer and two types of ion mobility spectrometry (i.

CaptiveSpray Differential Ion Mobility Spectrometry Device with Enhanced Ion Transmission and Improved Resolving Power.

A performance enhanced CaptiveSpray differential ion mobility device was designed and constructed by incorporating a circular channel and a gas flow homogenizing channel (GFHC) between the CaptiveSpray ion source and planar differential ion mobility spectrometry (DMS). The GFHC was used to reduce gas flow heterogeneity prior to the entrance of the DMS device. The optimal flared entrance greatly reduces gas flow velocity at the inlet region owing to its relatively large gas inlet interface, which assists in reducing disparities between the minimum and maximum gas velocity along the -axis.

Use of group IIB metal ions as charge carriers for collision-induced dissociation of glycopeptide and glycan.

Rationale: Dissociation of biomolecules by tandem mass spectrometry (MS/MS) generates a variety of fragment ions which provide useful information for the structural characterization of biomolecules. Different fragmentation strategies result in different mass spectra for the same molecule and thus provide distinct features. Charge carriers play important roles in determining the dissociation pathways of the target precursor ions.

Tandem Mass Spectrometry for Structural Characterization of Doubly-Charged N-Linked Glycopeptides.

Three dissociation methods, including collision-induced dissociation (CID), electron capture dissociation (ECD), and electronic excitation dissociation (EED), were systematically compared for structural characterization of doubly charged glycopeptide. CID produced distinctively different tandem mass spectra for glycopeptide adducted with different charge carriers. Protonated species produced mainly glycosidic cleavages in high abundance.

Dissociation of Mannose-Rich Glycans Using Collision-Based and Electron-Based Ion Activation Methods.

Three dissociation methods, including collision-induced dissociation (CID), electron capture dissociation (ECD), and electronic excitation dissociation (EED), were evaluated for the dissociation of doubly charged glycans using sodium or magnesium ions as charge carriers. CID produced mainly glycosidic cleavages, although more cross-ring fragment ions could be obtained at higher intensities when magnesium ions were used as charge carriers [M + Mg]. The A, A, and A ions provided structural information on the 3 → 1 and 6 → 1 linkages of the mannoses.

Development of a Matrix Sublimation Device with Controllable Crystallization Temperature for MALDI Mass Spectrometry Imaging.

The size and distribution of matrix crystals deposited on the surface of a tissue section play a key role in the performance of MALDI mass spectrometry imaging (MALDI-MSI). In this study, uniform distribution and a restricted size of matrix crystals were achieved via a homemade matrix sublimation device with controllable crystallization temperature. The crystallization temperature was stably controlled at a subzero temperature, and homogeneous matrix crystals with diameters <0.

Development of an All-in-One Protein Digestion Platform Using Sorbent-Attached Membrane Funnel-Based Spray Ionization Mass Spectrometry.

In this work, the sorbent-attached microfunnels used in funnel-based spray ionization mass spectrometry were evaluated for the all-in-one digestion of proteins. Sorbent materials, including C and TiO powders, were used as substrates to support in-funnel digestion and subsequent solid-phase extraction and purification of the digested products. In-funnel digestion protocols with and without reductive alkylation were developed for the analysis of proteins with and without disulfide linkages.

Magnetic solid-phase extraction of sulfonamide antibiotics in water and animal-derived food samples using core-shell magnetite and molybdenum disulfide nanocomposite adsorbent.

A molybdenum disulfide(MoS2)-based core-shell magnetic nanocomposite (FeO@MoS) was synthesized by the stepwise hydrothermal method. Two-dimension ultrathin MoS sheets with a thickness of approximately 20 nm were grown in situ on the surface of FeO (∼200 nm). They were employed as an adsorbent for the magnetic solid-phase extraction (MSPE) of sulfonamide antibiotics (SAs) from water samples.

Rapid Differentiation of Asian and American Ginseng by Differential Ion Mobility Spectrometry-Tandem Mass Spectrometry Using Stepwise Modulation of Gas Modifier Concentration.

This study reports a rapid and robust method for the differentiation of Asian and American ginseng samples based on differential ion mobility spectrometry-tandem mass spectrometry (DMS-MS/MS). Groups of bioactive ginsenoside/pseudo-ginsenoside isomers, including Rf/Rg/F, Rb/Rb/Rc, and Rd/Re, in the ginseng extracts were sequentially separated using DMS with stepwise changes in the gas modifier concentration prior to MS analysis. The identities of the spatially separated ginsenoside/pseudo-ginsenoside isomers were confirmed by their characteristic compensation voltages at specific modifier loading and MS/MS product ions.

Water-dispersible pH/thermo dual-responsive microporous polymeric microspheres as adsorbent for dispersive solid-phase extraction of fluoroquinolones from environmental water samples and food samples.

Multifunctional polymeric microspheres were prepared using hyper-cross-linking chemistry combined with surface-initiated atom transfer radical polymerization. The synthesized microspheres exhibited good water dispersibility, a high surface area, and pH/thermo dual-responsiveness. Fluoroquinolones (FQs), which contains a hydrophilic piperazine ring and hydrophobic fluorine atoms, were used as target analytes to assess the performance of the microspheres as a sorbent for dispersive solid-phase extraction (d-SPE).

Determination of fluoroquinolones in food samples by magnetic solid-phase extraction based on a magnetic molecular sieve nanocomposite prior to high-performance liquid chromatography and tandem mass spectrometry.

In this study, a magnetic molecular sieve material (FeO@MCM-48) was synthesized by a combination of solvothermal and self-assembly methods. The physicochemical properties of the magnetic molecular sieve material were characterized by scanning electron microscopy, energy-dispersive spectroscopy, magnetic hysteresis loop measurements, transmission electron microscopy, powder X-ray diffraction, N adsorption-desorption analysis, and Fourier transform infrared spectroscopy. The as-synthesized nanocomposite showed various advantages, including easy magnetic-assisted separation, high specific surface area, and a highly interwoven and branched mesoporous structure.

Performance Enhancements in Differential Ion Mobility Spectrometry-Mass Spectrometry (DMS-MS) by Using a Modified CaptiveSpray Source.

Differential ion mobility spectrometry (DMS) spatially separates ions in the gas phase using the mobility differences of the ions under applied low and high electric fields. The use of DMS as an ion filter (or ion selector) prior to mass spectrometry analysis has been compromised by the limited ion transmission efficiency. This paper reports enhancement of the DMS-MS sensitivity and signal stability using a modified CaptiveSpray™ source.

Electron-ion reaction-based dissociation: A powerful ion activation method for the elucidation of natural product structures.

The structural elucidation of natural products (NPs) remains a challenge due to their structurally diversities and unpredictable functionalities, motifs, and scaffolds. Tandem mass spectrometry (MS/MS) is an effective method that assists the full elucidation of complicated NP structures. Ion activation methods play a key role in determining the fragmentation pathways and the structural information obtained from MS/MS.

Tissue imaging with in situ solid-phase extraction micro-funnel based spray ionization mass spectrometry.

Current imaging mass spectrometry techniques are faced with a major challenge related to ion suppression effect. Data regarding low-abundance components or low-polarity compounds cannot be normally obtained presumably because of the discrimination effect of easily ionized chemical components on desorption/ionization process. In this study, a new method was proposed to obtain images of chemical components in biological tissues or sections through in situ solid-phase extraction in sorbent mounted micro-funnel based spray ionization mass spectrometry.

Structural Characterization of Intact Glycoconjugates by Tandem Mass Spectrometry Using Electron-Induced Dissociation.

Characterizing the structures of glycoconjungates is important because of glycan heterogeneity and structural complexity of aglycon. The presence of relatively weak glycosidic linkages leads to preferential cleavages that limit the acquisition of structural information under typical mass spectrometry dissociation conditions, such as collision-induced dissociation (CID) and infrared multiphoton dissociation. In this paper, we explored the dissociation behaviors of different members of glycoconjugates, including glycopeptides, glycoalkaloids, and glycolipids, under electron-induced dissociation (EID) conditions.

Generation and Characterization of Gas-Phase Doubly Charged Biradical Peptide Ions (M).

The gas-phase chemistry of peptide radical ions is attracting considerable interest in the fields of biology and mass spectrometry owing to its capability to provide sequence information on peptides and proteins. In this study, we observed that doubly charged peptide ions (M) can be produced from the collision-induced dissociation (CID) of Hg(II)-adducted peptide ions. The chemical nature and, thus, the dissociation pathways of this hydrogen-deficient biradical M species is intriguing.

Magnetic porous carbon derived from a bimetallic metal-organic framework for magnetic solid-phase extraction of organochlorine pesticides from drinking and environmental water samples.

In this work, magnetic porous carbon material derived from a bimetallic metal-organic framework was explored as an adsorbent for magnetic solid-phase extraction of organochlorine pesticides (OCPs). The synthesized porous carbon possessed a high specific surface area and magnetization saturation. The OCPs in the samples were quantified using gas chromatography coupled with a triple quadrupole mass spectrometer.

Metal-Organic Framework@Microporous Organic Network as Adsorbent for Solid-Phase Microextraction.

The practical applications of moisture sensitive metal-organic frameworks (MOFs) in the extraction technique are faced with avoided challenges related to competitive adsorption and hydrostability. The target analytes cannot be effectively extracted under humid conditions because of the competitive moisture adsorption and/or framework structure collapse of MOFs. In this Letter, metal-organic framework (MOF)@microporous organic network (MON) hybrid materials were explored for the first time as fiber coatings for solid-phase microextraction (SPME).

Magnetic metal-organic framework-titanium dioxide nanocomposite as adsorbent in the magnetic solid-phase extraction of fungicides from environmental water samples.

In this work, a core-shell Fe3O4@SiO2@MOF/TiO2 nanocomposite was synthesized and used to as adsorbent for magnetic solid-phase extraction (MSPE) of triazole fungicides from environmental water samples. Five triazole fungicides, namely, triadimenol, hexaconazole, diniconazole, myclobutanil, and tebuconazole, were selected as target analytes for MSPE. These analytes were quantitatively adsorbed on microspheres, and the sorbents were separated from the solution by using a magnet.