Disclosed are a rigorous method and apparatuses for the comprehensive analysis of complex mixtures of organic molecules, specifically biopolymers, in some embodiments predominantly mixtures of proteins, which in some embodiments ultimately serve to obtain the information constituting a biomarker, or similar biological signature, or to monitor health or ageing.

In some embodiments such signatures or patterns may indicate the presence, stage, or type of a disease, the expected or actual response to drugs. In some other embodiments such a method and apparatuses may serve to monitor and/or control cell development. In some other embodiments such a method and apparatuses may serve to develop and use means to measure, influence, or control the speed or degree of aging of cells or organisms.

In some embodiments such a method and apparatuses may serve to determine at least in part the nature of biological hazards, bioterrorism threats, or biological weapons, including those based on bacteria and viruses. In some embodiments such a method and apparatuses may serve to select, develop, and or optimize countermeasures to biological hazards, bioterrorism threats, or biological weapons, including those based on bacteria and viruses.

In other embodiments such a method and apparatuses may be used to asses the expected performance level of a human or animal for a specific task or for a class or problems.

Embodiments of a computer system, a method, and a computer-program product (e.g., software) for analyzing tandem-mass-spectrometry data are described. Using this analysis technique, unanticipated chemical modifications to peptides associated with proteins can be identified. In particular, a modification called a wild-card modification is used to identify the most likely chemical modifications in the peptides. A wild-card modification allows the addition of any mass, typically any integer atomic mass within a range, to any one amino acid residue within a candidate peptide.

Described herein are biosensor microarrays comprising detector polypeptide monolayers substantially free of contaminants. Also provided are methods for generation of such biosensor microarrays by capture of polypeptides by arrays comprising capture moieties and associated sensors.

Methods for in situ detecting proximity of two targets of interest featuring an antibody conjugated with a cleavable bridge component having a detectable moiety and an antibody conjugated with a non-cleavable bridge component. The bridge components each have a chemical ligation group adapted to form a covalent bond under particular conditions and when the targets are in close proximity. Following covalent bond formation, the cleavable bridge component can be cleaved from the antibody, effectively transferring the detectable moiety to the non-cleavable bridge component. Detection of the detectable moiety is indicative of the targets being in close proximity. The methods are compatible with both chromogenic and fluorogenic detection systems. The methods may be used to perform assays wherein one or more than one proximity event is detected on the same slide.

Systems and methods for obtaining qualitative or quantitative measurements of proteoforms of polypeptides are described. The described methods include measurements of affinity reagent binding on single-molecule polypeptide arrays to distinguish between polypeptide isoforms. The described methods may provide high resolution quantitative comparisons of proteoforms with very low copy numbers.

Antibodies against citrullinated protein antigens (ACPA) have shown their relevance for the diagnosis and possibly pathogenesis in arthritis. Described are means and methods for determining antibodies against homocitrulline-containing proteins or carbamylated proteins/peptides (anti-CarP) for the classification of individuals suffering from, or at risk of suffering from, arthritis.

Provided is a method for analyzing a protein-containing sample. The method comprises (1) dissolving a probe capable of non-specifically interacting with a plurality of proteins in a plurality of solvents having different ionic strengths and/or pH levels; (2) adding a protein-containing sample to a plurality of probe solutions prepared in the step (1), thereby the proteins in the sample and the probe are interacted non-specifically; (3) measuring the fluorescence intensities of the plurality of probe solutions to which the protein-containing sample was added in the step (2); and (4) comparing the pattern of fluorescence intensities obtained in the step (3) with the pattern of fluorescence intensities obtained from a reference sample.

The present disclosure provides a method for accurately measuring post-translational modifications in proteins such as antibodies. In particular, the method pertains to the use of heavy isotopic standards to generate a calibration curve to allow for accurate quantitation of a modified peptide. The method may be used to accurately quantify C-terminal truncation in antibodies using mass spectrometry.

The description relates to a method and kits for determining the total carbonylation level on a polypeptide.

Compositions and methods for identifying glucuronylated protein drug products are provided.