The present invention generally pertains to methods of determining the amino acid sequence of a protein. In particular, the present invention pertains to the use of position-selective dimethylation and liquid chromatography-mass spectrometry to enhance the signal of N-terminal peptides and shift the signal of N-terminal peptides and corresponding b ions, thus facilitating a determination of the sequence of N-terminal peptides.

A method for determining a quantity of an analyte in a liquid sample, comprises: adding a known quantity of an internal standard comprising an isotopically labeled version of the analyte to the sample; (b) providing a continuous stream of the sample having the internal standard to an inlet of a Liquid Chromatography Mass Spectrometry (LCMS) system; and repeatedly performing the steps of: performing a data-independent analysis of the precursor ion species using a mass analyzer, whereby mass spectra of a plurality of fragment-ion species are acquired; calculating one or more degree-of-matching scores that relate to either a number of ions of the internal standard that overlap between results of the data-independent analysis and tabulated mass spectral data of the internal standard; and performing quantitative tandem mass spectrometric analyses of the internal standard and the analyte if each of the degree-of-matching scores meets a respective degree-of-matching condition.

The present invention relates to a method for predicting and monitoring the severity of COVID-19 disease following infection of a subject with the SARS-CoV-2 virus. It also relates to a method for the treatment of a subject with COVID-19 disease. It also relates to kits for use in the methods of the invention.

Methods are described for determining the amount of insulin in a sample. Provided herein are mass spectrometric methods for detecting and quantifying insulin and C-peptide in a biological sample utilizing enrichment and/or purification methods coupled with tandem mass spectrometric or high resolution/high accuracy mass spectrometric techniques. Also provided herein are mass spectrometric methods for detecting and quantifying insulin and b-chain in a biological sample utilizing enrichment and/or purification methods coupled with tandem mass spectrometric or high resolution/high accuracy mass spectrometric techniques.

The present invention relates to the field of protein characterization, and in particular to methods for identifying critical quality attributes of therapeutic proteins by implementing a workflow including using a competitive binding assay with insufficient capture molecule followed by LC-MS.

The invention pertains to the use of a specific biomarker of elastin degradation (desmosine) that measures the extent and progression of chronic obstructive pulmonary disease (COPD). In addition to potentially serving as a screening procedure for COPD, it provides a real-time measure of COPD drug efficacy and may therefore supersede the use of less sensitive tests such as pulmonary function studies and computed tomography. Equally important, the current invention constitutes a marked improvement for measuring desmosine in tissues and body fluids by greatly shortening the time for detection of this molecule in liquid chromatography-tandem mass spectrometry (LC-MS-MS) assays that are the gold standard for such measurements. Unlike previous methods, the invention allows for the use of LC-MS-MS without modification, so the method can be applied to any laboratory that uses this equipment for other measurements. This would include forensic facilities that need to determine if undiagnosed COPD played a role in the loss of life.

Methods and system for identifying and quantifying antibody fragments and identifying the site of fragmentation on an antibody are provided herein.

The present invention is directed to an anti-adsorption solution for the analysis of peptides. Also a process for the preparation of such an anti-adsorption solution and the use of said anti-adsorption solution are described.

The invention relates to methods for the quantification of glycoproteins in a sample, comprising quantifying said glycoproteins by comparison with an internal standard, wherein said internal standard comprises variant forms of said glycoproteins, wherein said variant forms contain only core Asn-linked GlcNAc moieties.

Described herein are methods for evaluating polymer compositions comprising polymers modified with a polypeptide (e.g., a cell-binding polypeptide), including methods for determining polypeptide concentration.