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Protein glycosylation, one of the most heterogeneous post-translational modifications, can play a major role in cellular signal transduction and disease progression. Traditional mass spectrometry (MS)-based large-scale glycoprotein sequencing studies heavily rely on identifying enzymatically released glycans and their original peptide backbone separately, as there is no efficient fragmentation method to produce unbiased glycan and peptide product ions simultaneously in a single spectrum, and that can be conveniently applied to high throughput glycoproteome characterization, especially for N-glycopeptides, which can have much more branched glycan side chains than relatively less complex O-linked glycans. In this study, a redefined electron-transfer/higher-energy collision dissociation (EThcD) fragmentation scheme is applied to incorporate both glycan and peptide fragments in one single spectrum, enabling complete information to be gathered and great microheterogeneity details to be revealed. Fetuin was first utilized to prove the applicability with 19 glycopeptides and corresponding five glycosylation sites identified. Subsequent experiments tested its utility for human plasma N-glycoproteins. Large-scale studies explored N-glycoproteomics in rat carotid arteries over the course of restenosis progression to investigate the potential role of glycosylation. The integrated fragmentation scheme provides a powerful tool for the analysis of intact N-glycopeptides and N-glycoproteomics. We also anticipate this approach can be readily applied to large-scale O-glycoproteome characterization. [ABSTRACT FROM AUTHOR]

The D-residues are crucial to biological function of D-amino acid containing peptides (DAACPs). Previous ion mobility mass spectrometry (IM-MS) studies revealing oligomerization patterns of amyloid cascade demonstrated conversion from native soluble unstructured assembly to fibril ß-sheet oligomers, which has been implicated in amyloid diseases, such as Alzheimer's disease and type 2 diabetes. Although neuropeptides are typically present at very low concentrations in circulation, their local concentrations could be much higher in large dense core vesicles, forming dimers or oligomers. We studied the oligomerization of protonated and metal-adducted achatin I and dermorphin peptide isomers with IM-MS. Our results suggested that dimerization, oligomerization, and metal adduction augment the structural differences between D/L peptide isomers compared to protonated monomers. Dimers and oligomers enhanced the structural differences between D/L peptide isomers in both aqueous and organic solvent system. Furthermore, some oligomer forms were only observed for either D- or L-isomers, indicating the importance of chiral center in oligomerization process. The oligomerization patterns of D/L isomers appear to be similar. Potassium adducts were detected to enlarge the structural differences between D/L isomers. [ABSTRACT FROM AUTHOR]

In order to understand broadband photodetectors from ultraviolet-visible (UV-vis) to the near-infrared range, one needs to find novel two-dimensional (2D) van der Waals (vdW) materials with broadband optoelectronic performance. Transition metal phosphorus sulfides (TMPSs) have been reported as a new type of vdW material with generally broadband and p-type conductivity. Here, we report a high-performance and broadband photodetector consist of p-type FePS 3 and n-type WS 2 with a working range of 405-785 nm. The maximum values of responsivity and specific detectivity are 32.5 mA/W and 1.73 × 10 12 jones at 405 nm and 2 V bias, which are better than those of its individual constituents and many other 2D vdW heterostructures. The high performance of the FePS 3 /WS 2 photodetector is attributed to the built-in electric field in the FePS 3 /WS 2 p-n heterostructure and type II band alignment. Present study demonstrates that the material family of TMPSs could be a promising platform for broadband photodetector applications.

Crustaceans are commonly used model organisms to study neuromodulation. Despite numerous reported crustacean neuropeptide families and their functions, there has been no report on neuropeptide glycosylation. This is in part due to a lack of sensitive methods that enable deciphering this intricate low-abundance post-translational modification, even though glycosylation has been shown to play an important role in neuromodulation. Here, we describe the discovery of glycosylated neuropeptides with an enrichment-free approach, taking advantage of signature oxonium ions produced in higher-energy collision dissociation (HCD) MS/MS spectra. The detection of the oxonium ions in the HCD scans suggests glycan attachment to peptides, allowing electron-transfer/higher-energy collision dissociation (EThcD) to be performed to selectively elucidate structural information of glycosylated neuropeptides that are buried in nonglycosylated peptides. Overall, 4 N-linked and 14 O-linked glycosylated neuropeptides have been identified for the first time in the crustacean nervous system. In addition, 91 novel putative neuropeptides have been discovered based on the collected HCD scans. This hybrid approach, coupling a shotgun method for neuropeptide discovery and targeted strategy for glycosylation characterization, enables the first report on glycosylated neuropeptides in crustaceans and the discovery of additional neuropeptides simultaneously. The elucidation of novel glycosylated neuropeptides sheds light on the crustacean peptidome and offers novel insights into future neuropeptide functional studies.

Ultraviolet (UV) radiation has a variety of impacts including the health of humans, the production of crops, and the lifetime of buildings. Based on the photovoltaic effect, self-powered UV photodetectors can measure and monitor UV radiation without any power consumption. However, the current low photoelectric performance of these detectors has hindered their practical use. In our study, a super-high-performance self-powered UV photodetector based on a GaN/Sn:Ga 2 O 3 pn junction was generated by depositing a Sn-doped n-type Ga 2 O 3 thin film onto a p-type GaN thick film. The responsivity at 254 nm reached up to 3.05 A/W without a power supply and had a high UV/visible rejection ratio of R 254 nm / R 400 nm = 5.9 × 10 3 and an ideal detectivity at 1.69 × 10 13 cm·Hz 1/2 ·W -1 , which is well beyond the level of previous self-powered UV photodetectors. Moreover, our device also has a low dark current (1.8 × 10 -11 A), a high I photo / I dark ratio (∼10 4 ), and a fast photoresponse time of 18 ms without bias. These outstanding performance results are attributed to the rapid separation of photogenerated electron-hole pairs driven by a high built-in electric field in the interface depletion region of the GaN/Sn:Ga 2 O 3 pn junction. Our results provide an improved and easy route to constructing high-performance self-powered UV photodetectors that can potentially replace traditional high-energy-consuming UV detection systems.

Recently developed carbonyl-reactive aminoxy tandem mass tag (aminoxyTMT) reagents enable multiplexed characterization and quantitative comparison of structurally complex glycans between different biological samples. Compared to some previously reported isotopic labeling strategies for glycans, the use of the aminoxyTMT method features a simple labeling procedure, excellent labeling efficiency, and reduced spectral complexity at the MS(1) level. Presence of the tertiary amine functionality in the reporter region of the aminoxyTMT labels leads to increased ionization efficiency of the labeled glycans thus improving electrospray ionization (ESI)-mass spectrometry (MS) detection sensitivity. The use of the labeling reagent also makes electrophoretic separation of the labeled neutral and acidic glycans feasible. In this work, we characterized the ESI and collision induced dissociation (CID) behavior of the aminoxyTMT-labeled neutral and sialylated glycans. For the high-mannose N-glycans and small sialylated oligosaccharides, CID fragmentation of [M + Na + H](2+) provides the most informative MS(2) spectra for both quantitative and qualitative analysis. For complex N-glycans, MS(3) of the protonated Y1(H) ion can be used for relative quantification without interference from the HexNAc fragments. Online capillary electrophoresis (CE)-ESI-MS/MS analyses of multiplexed aminoxyTMT-labeled human milk oligosaccharides (HMOs) and different types of N-glycans released from glycoprotein standards were demonstrated. Improved resolution and quantification accuracy of the labeled HMO isomers was achieved by coupling CE with traveling wave ion mobility (TWIM)-CID-MS/MS. N-Glycans released from human serum protein digests were labeled with six-plex aminoxyTMT and subjected to CE-ESI-MS/pseudo-MS(3) analysis, which demonstrated the potential utility of this glycan relative quantification platform for more complex biological samples.