Fabrication of Alkoxyamine-Functionalized Magnetic Core-Shell Microspheres via Reflux Precipitation Polymerization for Glycopeptide Enrichment

ANALYSIS OF CARBOHYDRATES AND GLYCOCONJUGATES BY MATRIX-ASSISTED LASER DESORPTION/IONIZATION MASS SPECTROMETRY: AN UPDATE FOR 2015-2016

This review is the ninth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2016. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented over 30 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show no sign of deminishing. © 2020 Wiley Periodicals, Inc.

Elution-free ultra-sensitive enrichment for glycopeptides analyses: Using a degradable, post-modified Ce-metal-organic framework

In this work, we presented a facile elution-free method for ultrasensitive enrichment of glycopeptides using two kinds of novel Ce-metal-organic frameworks (Ce-MOF) post-modified with hyaluronic acid (Ce-MOF@HA) and glutamic acid (Ce-MOF@Glu). Both of the synthesized materials remained stable in the loading buffer to enrich glycopeptides selectively and degrade in the eluent to release captured glycopeptides. Due to the dissolution of materials, the elution step of the enrichment process is omitted, resulting in an extremely high sensitivity (detection limit, 0.5 fmol/μL). Meanwhile, Ce-MOF@HA and Ce-MOF@Glu also possessed excellent selectivity with molar ratios of IgG and BSA digests being 1:1000 and 1:500, respectively. Noticeably, the practical applicability of the obtained materials was inspected by analyzing the glycopeptides enriched from human serum (2 μL) by nano-LC-MS, in which 434 N-glycopeptides from 182 N-glycoproteins (by Ce-MOF@HA) and 328 N-glycopeptides from 135 N-glycoproteins (by Ce-MOF@Glu) were detected, respectively. This work provides a new method to simplify the process of glycopeptides enrichment and also paves a novel way for the enrichment of trace targets from complex matrices.

Ultradeep Palmitoylomics Enabled by Dithiodipyridine-Functionalized Magnetic Nanoparticles

Palmitoylation, a type of fatty acylation, has vital roles in many biological processes. For ultradeep identification of protein palmitoylation, an enrichment approach based on a novel magnetic microsphere modified with 2,2'-dithiodipyridine (Fe₃O₄/SiO₂-SSPy microsphere) is presented in this study. The Fe₃O₄/SiO₂-SSPy microspheres were synthesized by directly coating thiol-containing silane coupling agent onto the magnetic supraparticles in aqueous solution at room temperature. Due to the intrinsic magnetic properties, high surface-to-volume ratios, and abundant reactive functional groups on the surface, these microspheres enabled direct capture of palmitoylated targets and convenient isolation, contributing to remarkable enrichment selectivity (purifying palmitoylated peptides from mixtures with nonpalmitoylated peptides even at a 1:500 molar ratio) and sensitivity (the detection limit was at femtomole level), thus enabling a global annotation of protein palmitoylation for complex biological samples. We successfully identified 1304 putative palmitoylated proteins from mouse brain tissues by using this method, which is the largest mouse palmitoylome data set to date. Except for those known members, many new proteins and pathways were also found to be regulated by palmitoylation.