Provided is a sensitive and specific LC-MS-MRM quantification method that distinguishes outer-arm and core fucosylated configurations of N-glycopeptides. Advantage is taken of limited fragmentation of the glycopeptides at low collision energy (collision-induced dissociation) CID to produce linkage-specific Y-ions. These ions are selected as multiple reaction monitoring (MRM) transitions for the quantification of the outer-arm and total fucosylation of 23 glycoforms of 9 glycopeptides in 7 plasma proteins. The method permits quantification of the glycoforms directly in plasma or serum without fractionation of samples or glycopeptide enrichment. A pilot study of fucosylation in liver cirrhosis of hepatitis C vims (HCV) and non-alcoholic steatohepatitis (NASH) etiologies demonstrated that liver cirrhosis is consistently associated with increased outer-arm fucosylation of a majority of the analyzed proteins. The outer-arm fucosyaltion of the A2G2F1 glycoform of the VDKDLQSLEDILHQVENK peptide of fibrinogen was found to increase more than 10-fold in the cirrhosis patients compared to healthy controls.

Antibodies that selectively bind to glycosylated PD-1 relative to unglycosylated PD-1 are provided. In some aspects, PD-1 polypeptides comprising glycosylated amino acid positions are also provided. Methods for making and using such antibodies and polypeptides (e.g., for the treatment of cancer) are also provided.

Provided are methods of determining an amount of alpha-dystroglycan (αDG) in a sample, determining an amount of the glycosylated form of αDG in the sample, and determining a ratio of the amount of the glycosylated form of αDG to the amount of αDG in the sample.

Methods for peptide and/or protein quantification by mass spectrometry using labeled peptides, wherein multiple labels lead to distinct fragments for the labeled peptides and their unlabeled variant, thus facilitating data analysis and enhancing the potential for quantification. Methods for selecting the label and label position are further given, as well as sets of labeled peptides resulting from or for use in the above-mentioned methods. The methods and substances are especially useful for data-independent or multiplexed parallel reaction monitoring proteomics applications involving peptide quantification.

Antibodies that selectively bind to glycosylated PD-1 relative to unglycosylated PD-1 are provided. In some aspects, PD-1 polypeptides comprising glycosylated amino acid positions are also provided. Methods for making and using such antibodies and polypeptides (e.g., for the treatment of cancer) are also provided.

Methods for peptide and/or protein quantification by mass spectrometry using labeled peptides, wherein multiple labels lead to distinct fragments for the labeled peptides and their unlabeled variant, thus facilitating data analysis and enhancing the potential for quantification. Methods for selecting the label and label position are further given, as well as sets of labeled peptides resulting from or for use in the above-mentioned methods. The methods and substances are especially useful for data-independent or multiplexed parallel reaction monitoring proteomics applications involving peptide quantification.

The disclosure relates to methods of analyzing a post-translationally modified protein of interest using electrophoresis, the methods comprising deglycosylating the protein of interest after labeling.

The present disclosure an ELISA-based assay that uses a glycosylated polypeptide fragment derived from the SARS-CoV-2 spike protein (Covid-19) receptor binding domain (S1RBD) that has affinity for the extracellular domain of Angiotensin Converting Enzyme 2 (ACE2). The S1RBD polypeptide is generated by expression of an encoding nucleic acid by a human cell expression system resulting in glycosylation of the expressed spike receptor binding domain (S1RBD) protein at least at the N343 N-glycosylation site thereof, and which surprisingly and significantly increases the affinity of the S1RBD for ACE2, provides a significant increase in the sensitivity of the assay compared to other known assays.

The present invention relates a method for maximizing the coronavirus killing activity of high-density lipoproteins, and a pharmaceutical composition for preventing or treating COVID-19. As identified by the present inventors, non-glycated normal high-density lipoproteins (HDLs) exhibit killing activity against coronavirus (SARS-Cov-2) that is superior to that of glycated HDLs, and thus a pharmaceutical composition for preventing and treating COVID-19, containing non-glycated native HDLs as an active ingredient, is provided. In addition, the present invention is useful since a method for maximizing the coronavirus killing activity by using an HDL glycation inhibitor, on the basis of the identification by the present inventors, can be provided and a method for screening for a pharmaceutical composition for preventing and treating COVID-19 by evaluating the degree of HDL glycosylation inhibition of candidate drugs can be provided.

The invention aims to provide a non-destructive method of testing and analysing, amongst other things, cell types such as pluripotent cells, including differentiated cells and MSCs. The invention also aims to provide a non-destructive method to test and analyse the cell conditions, such as aging, activity, multipotency, differentiated directivity and effectiveness. Possibility of analysing cell types or cell conditions without destroying the cells by analyzing glycan profile, which is acquired from glycoconjugates secreted from cells in culture mediums, using microarrays with glycan binding protein, on the surface was discovered.