Direct visualization of the drug release process of non-conductive polymeric implants via molecular imaging.

Long-acting parenteral (LAP) implant has garnered the attraction as a drug delivery technique in recent years. Understanding the drug release process is critical for the study of underlying release mechanism. In this paper, we present a novel application of matrix-assisted laser desorption/ionization-mass spectrometry imaging (MADLI-MSI) for the direct visualization of the drug release process from non-conductive polymeric based LAP implants at molecular level.

Determination of modification sites and relative quantitation in large protein conjugation via automated data processing.

Protein conjugation is an effective way to impart different functionalities to the original protein. Conjugation using a native protein (a protein that does not contain special unnatural amino acid for conjugation) typically generates complex mixtures mainly due to the presence of multiple chemically similar competing conjugation sites. It is therefore a challenge to identify products, to optimize the reaction conditions, and to synthesize desired molecules.

Peptide Sequence Influence on the Differentiation of Valine and Norvaline by Hot Electron Capture Dissociation.

Isomeric amino acid residues such as valine (Val) and norvaline (Nva) are common in recombinant proteins. The mis-incorporation of Nva for leucine (Leu) causes heterogeneity and in some cases even toxicity. Previous studies have shown that hot electron capture dissociation (HECD) is able to differentiate Val from Nva by producing diagnostic w ions on custom designed synthetic model peptides.

Characterization of Disulfide-Linked Peptides Using Tandem Mass Spectrometry Coupled with Automated Data Analysis Software.

Disulfide bond formation is critical for maintaining structure stability and function of many peptides and proteins. Mass spectrometry has become an important tool for the elucidation of molecular connectivity. However, the interpretation of the tandem mass spectral data of disulfide-linked peptides has been a major challenge due to the lack of appropriate tools.

Investigation of signaling molecules and metabolites found in crustacean hemolymph via in vivo microdialysis using a multifaceted mass spectrometric platform.

Neurotransmitters (NTs) are endogenous signaling molecules that play an important role in regulating various physiological processes in animals. Detection of these chemical messengers is often challenging due to their low concentration levels and fast degradation rate in vitro. In order to address these challenges, herein we employed in vivo microdialysis (MD) sampling to study NTs in the crustacean model Cancer borealis.

Development and characterization of novel 8-plex DiLeu isobaric labels for quantitative proteomics and peptidomics.

Rationale: Relative quantification of proteins via their enzymatically digested peptide products determines disease biomarker candidate lists in discovery studies. Isobaric label-based strategies using TMT and iTRAQ allow for up to 10 samples to be multiplexed in one experiment, but their expense limits their use. The demand for cost-effective tagging reagents capable of multiplexing many samples led us to develop an 8-plex version of our isobaric labeling reagent, DiLeu.

Data-independent MS/MS quantification of neuropeptides for determination of putative feeding-related neurohormones in microdialysate.

Food consumption is an important behavior that is regulated by an intricate array of neuropeptides (NPs). Although many feeding-related NPs have been identified in mammals, precise mechanisms are unclear and difficult to study in mammals, as current methods are not highly multiplexed and require extensive a priori knowledge about analytes. New advances in data-independent acquisition (DIA) MS/MS and the open-source quantification software Skyline have opened up the possibility to identify hundreds of compounds and quantify them from a single DIA MS/MS run.

Mass spectrometric measurement of neuropeptide secretion in the crab, Cancer borealis, by in vivo microdialysis.

Neuropeptides (NPs), a unique and highly important class of signaling molecules across the animal kingdom, have been extensively characterized in the neuronal tissues of various crustaceans. Because many NPs are released into circulating fluid (hemolymph) and travel to distant sites in order to exhibit physiological effects, it is important to measure the secretion of these NPs from living animals. In this study, we report on extensive characterization of NPs released in the crab Cancer borealis by utilizing in vivo microdialysis to sample NPs from the hemolymph.

Mass spectrometric analysis of spatio-temporal dynamics of crustacean neuropeptides.

Neuropeptides represent one of the largest classes of signaling molecules used by nervous systems to regulate a wide range of physiological processes. Over the past several years, mass spectrometry (MS)-based strategies have revolutionized the discovery of neuropeptides in numerous model organisms, especially in decapod crustaceans. Here, we focus our discussion on recent advances in the use of MS-based techniques to map neuropeptides in the spatial domain and monitoring their dynamic changes in the temporal domain.

Gas-phase ion isomer analysis reveals the mechanism of peptide sequence scrambling.

Peptide sequence scrambling during mass spectrometry-based gas-phase fragmentation analysis causes misidentification of peptides and proteins. Thus, there is a need to develop an efficient approach to probing the gas-phase fragment ion isomers related to sequence scrambling and the underlying fragmentation mechanism, which will facilitate the development of bioinformatics algorithm for proteomics research. Herein, we report on the first use of electron transfer dissociation (ETD)-produced diagnostic fragment ions to probe the components of gas-phase peptide fragment ion isomers.

Mass spectrometric characterization of the neuropeptidome of the ghost crab Ocypode ceratophthalma (Brachyura, Ocypodidae).

The horn-eyed ghost crab Ocypode ceratophthalma is a terrestrial brachyuran native to the Indo-Pacific region, including the islands of Hawaii. Here, multiple mass spectrometric platforms, including matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS) and nanoflow liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (nanoLC-ESI-Q-TOF MS/MS), were used to characterize the neuropeptidome of this species. In total, 156 peptide paracrines/hormones, representing 15 peptide families, were identified from the O.

Oxidative aromatic C-O bond formation: synthesis of 3-functionalized benzo[b]furans by FeCl3-mediated ring closure of alpha-aryl ketones.

A variety of 3-functionalized benzo[b]furans were achieved by way of a FeCl(3)-mediated intramolecular cyclization of electron-rich alpha-aryl ketones. The alkoxy substituent on the benzene ring in the substrates was essential for an efficient cyclization to occur. This novel method allows the construction of benzo[b]furan rings by joining the O-atom on the side chain to the benzene ring via direct oxidative aromatic C-O bond formation.

Simple conversion of enamines to 2H-azirines and their rearrangements under thermal conditions.

A variety of substituted enamine derivatives were first found to be conveniently converted to the corresponding 2H-azirines mediated by phenyliodine (III) diacetate (PIDA). The formed 2-aryl-2H-azirines could be applied in the synthesis of indole-3-carbonitriles or isoxazoles via thermal rearrangements.