Chemoselective conjugation is achieved through redox reactivity by reacting an N-transfer oxidant with a thioether substrate in a redox reaction in an aqueous environment to form a conjugation product. In embodiments, Redox-Activated Chemical Tagging (ReACT) strategies for methionine-based protein functionalization. Oxaziridine (Ox) compounds serve as oxidant-mediated reagents for direct functionalization by converting methionine to the corresponding sulfimide conjugation product.

Compositions and methods for identifying free thiols in protein are provided. An exemplary method labeling peptides with a tag to identify free thiols and a tag to identify native disulfide bonds and analyzing the tags using targeted MS.sup.2. In one embodiment, the method provides complete coverage of all 32 cysteine residues in an IgG molecule. In other embodiments the method covers the 16 cysteine residues on the heavy and light chains in an IgG molecule. In another embodiment, the method covers the 5 cysteine residues on each light chain of an IgG molecule. In another embodiment, the method covers the 11 cysteine residues on each heavy chain of an IgG molecule.

A compound in which a xanthene colorant is bonded to an optical absorber (Dye) with optical absorption in the wavelength range of 350 to 700 nm.

A method for evaluating a sample includes obtaining a blood plasma sample prepared from human blood, conducting detection of a predetermined molecule in the blood plasma sample, and evaluating the quality of the blood plasma sample based on the intensity of the molecule acquired by the detection.

The present disclosure provides a marker and use thereof in predicting a possibility of a subject with diabetes. The marker described may include at least one of α-hydroxybutyric acid (α-HB), 1,5-anhydroglucitol (1,5-AG), asymmetric dimethylarginine (ADMA), cystine, ethanolamine, taurine, L-leucine, L-tryptophan, hydroxylysine, and L-aspartate. The possibility of the subject with diabetes may be predicted using a prediction model (e.g., prediction models 2-5) related to the marker based on a concentration of the marker. The prediction model 2 is related to α-HB. The prediction model 3 is related to 1,5-AG and ADMA. The prediction model 4 is related to cystine, ethanolamine, taurine, L-leucine, L-tryptophan and hydroxylysine. The prediction model 5 is related to α-HB, 1,5-AG, cystine, ethanolamine, taurine and L-aspartate.

The present invention relates to a method for metabolite sampling and analysis for reproducibly sampling as many metabolites as possible in a urine sample without changing to metabolites. The method has effects of presenting a biomarker detection method according to the sex or the like, by establishing optimal conditions for metabolite sampling in urine samples and presenting a metabolite comparison analysis method between different groups on the basis of the optimal conditions.

A method of treating an inflammatory condition with a hydroxytyrosol-rich composition. Improvement is monitored as a reduction in the levels of a biochemical marker such as homocysteine or C-reactive protein. The composition may be administered in an amount and for a period sufficient to effect a drop in the level of the biochemical marker.

Compositions and methods for analyzing disulfide bonds are provided. An exemplary method includes preparing peptide standards having no disulfide bonds, scrambled disulfide bond peptide standards, and native disulfide bond peptide standards according to the sequence of the region of the protein drug product that includes the disulfide bond, digesting a sample of protein drug product into peptides, separating the protein drug product peptides, analyzing the protein drug product peptides and the peptide standards, identifying scrambled and native disulfide bond peptides by retention time, and quantifying the level of scrambled disulfide bond peptides.

The present disclosure provides a marker and use thereof in predicting a possibility of a subject with diabetes. The marker described may include at least one of α-hydroxybutyric acid (α-HB), 1,5-anhydroglucitol (1,5-AG), asymmetric dimethylarginine (ADMA), cystine, ethanolamine, taurine, L-leucine, L-tryptophan, hydroxylysine, and L-aspartate. The possibility of the subject with diabetes may be predicted using a prediction model (e.g., prediction models 2-5) related to the marker based on a concentration of the marker. The prediction model 2 is related to α-HB. The prediction model 3 is related to 1,5-AG and ADMA. The prediction model 4 is related to cystine, ethanolamine, taurine, L-leucine, L-tryptophan and hydroxylysine. The prediction model 5 is related to α-HB, 1,5-AG, cystine, ethanolamine, taurine and L-aspartate.

A fluorescent protein sensor capable of quantitatively measuring oxidation degree of methionine residues of a specific protein, and a use thereof. Specifically, a fluorescent biosensor recombinant protein in which an MsrB protein, a cpYFP protein, a thioredoxin 3 protein, a linker protein and a G protein are linked in this order, and which is capable of quantitatively measuring the oxidation degree of methionine residues of a target protein; a fluorescent biosensor comprising same; a method for measuring oxidation degree of methionine residues of a target protein; and an information providing method for diagnosis of oxidative stress-associated diseases; and a method for screening for a therapeutic agent for oxidative stress-associated diseases. A recombinant protein for a fluorescent biosensor for accurately and quantitatively measuring, through the detection of a specific change in fluorescence, oxidation degree of methionine residues of a specific protein, but not all proteins, even in a mixed biological sample.