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.

A method for determining in a sample, by liquid chromatography/mass spectrometry, the presence, absence, or amount of one or more or a plurality of analytes is described. The method comprises subjecting the sample to an ionization source under conditions suitable to produce one or more ions detectable by mass spectrometry from each of the one or more of the analytes; measuring, by liquid chromatography/mass spectrometry, the amount of the one or more ions from each of the one or more analytes; and using the measured amount of the one or more ions to determine the presence, absence, or amount of each of the one or more or plurality of analytes in the sample.

In a method for analyzing isoaspartic acid by dissociating precursor ions derived from a sample component and generating and analyzing product ions, the method includes: generating product ions by irradiating the precursor ions with hydrogen radicals or radicals having oxidizing ability to dissociate the precursor ions; separating and detecting the product ions according to a mass-to-charge ratio; and specifying product ions derived from isoaspartic acid based on a mass-to-charge ratio of the product ions.

Purine-derived covalent probes (e.g., halo or di-halo-substituted purine based covalent probes) and related ligands are described. The compounds can be used to identify reactive nucleophilic amino acid residues, such as reactive cysteine residues, in proteins and to modify the activity of proteins with reactive nucleophilic amino acid residues (e.g., reactive cysteine residues) via the formation of protein adducts comprising the ligands Modified proteins prepared from the probes and ligands are also described.

The present disclosure discloses a mass spectrometry based method for detecting serum metabolite, and relates to the technical field of mass spectrometric detection. The method includes: analyzing detection matching values of detection personnels receiving a detection task, and selecting a detection personnel with the largest detection matching value as a selected detection personnel; firstly performing position matching, then performing configuration to obtain a serum sample, and performing mass spectrometric detection on the serum sample after the selected detection personnel reaches a detection position; verifying a fingerprint of the selected detection personnel before the selected detection personnel uploads mass spectrometric result data; and stamping the mass spectrometric result data with a time mark and uploading the mass spectrometric result data to a detection platform for storage by the selected detection personnel through a mobile phone terminal after the fingerprint verification is passed, ensuring the authenticity and safety of the data.

Methods and system for identifying and/or quantifying a protein are provided herein.

The present disclosure provides a system comprising a communication interface and computer for assigning a label to the biomolecule fingerprint, wherein the label corresponds to a biological state. The present disclosure also provides a sensor arrays for detecting biomolecules and methods of use. In some embodiments, the sensor arrays are capable of determining a disease state in a subject.

Methods and system for identifying and/or quantifying a protein are provided herein.

Our biology, in health and disease, is characterized by multiple cooperating molecules in highly regulated networks. Derangements of these networks can identify imminent severe worsening of disease, known as “the tipping point”. Identifying this change early has been shown to predict worsening, but also, to reveal opportunities for specific molecular therapies to halt disease progression. Unfortunately, there are no tools currently available to characterize molecular networks in humans or to see important changes coming. The current invention is a computer system linked to computer networks and data sources, to micro- and milli-fluidic sampling and assay devices. It uses advanced data analytics to examine the available data and to learn how to recognize impending trouble at a time when there are recognizable processes to block, and before it is too late for treatment.

Methods are described for measuring the amount of a vitamin B2 in a sample. More specifically, mass spectrometric methods are described for detecting and quantifying vitamin B2 in a sample utilizing on-line extraction methods coupled with tandem mass spectrometric techniques.