The present description provides methods, assays and reagents useful for sequencing proteins. Sequencing proteins in a broad sense involves observing the plausible identity and order of amino acids, which is useful for sequencing single polypeptide molecules or multiple molecules of a single polypeptide. In one aspect, the methods are useful for sequencing multiple polypeptides. The methods and reagents described herein can be useful for high resolution interrogation of the proteome and enabling ultrasensitive diagnostics critical for early detection of diseases.

Provided are affinity-based methods of isolating biological entities via a surface antigen from a sample with non-chromatographic and chromatographic methods being provided. Also provided is a dextran polymer, kits for use in the method of isolating a biological entity and an apparatus for performing the methods.

Compositions useful for the detection of single molecules in a sample are provided. In some aspects, the disclosure provides a nucleotide connected to a nucleic acid comprising a FRET label comprising at least three luminescent molecules. In some embodiments, the nucleic acids described herein comprise one or more structural features that provide enhanced fluorescence intensity. In some aspects, methods of sequencing using the labeled nucleotides of the disclosure are provided.

A method for analyzing macromolecules, including peptides, polypeptides, and proteins, employing nucleic acid encoding is disclosed.

Aspects of the application provide methods of identifying and sequencing proteins, polypeptides, and amino acids, and compositions useful for the same. In some aspects, the application provides methods of obtaining data during a degradation process of a polypeptide, and outputting a sequence representative of the polypeptide. In some aspects, the application provides amino acid recognition molecules comprising a shielding element that enhances photostability in polypeptide sequencing reactions.

The present disclosure relates to a system, method, and kit for particle detection and analysis. Devices disclosed herein may include at least an optical source, a fluidic chip containing a multiplex bead array, and a detection module, wherein the sample flows within the fluidic chip past a detection window, where the cells or particles are imaged by an image acquisition and analysis module that may include an optical detector. The image acquisition and analysis module counts the labeled particles and software allows for analysis of bead population.

The present disclosure provides, inter alia, genetically encoded recombinant peptide biosensors comprising analyte-binding framework portions and signaling portions, wherein the signaling portions are present within the framework portions at sites or amino acid positions that undergo a conformational change upon interaction of the framework portion with an analyte.

The invention provides an assay for assessing the conformational stability of a membrane protein, comprising: (a) providing a sample comprising a first population and a second population of a membrane protein; wherein the membrane protein in the first population is labelled with a donor label and the membrane protein in the second population is labelled with an acceptor label, or the membrane protein in the first population is labelled with an acceptor label and the membrane protein in the second population is labelled with a donor label, (b) exposing the first and second populations of the membrane protein to a stability modulating agent and/or condition, (c) and assessing aggregation between membrane proteins of the first and second populations by activating the donor label to permit a distance-dependent interaction with the acceptor label, which interaction produces a detectable signal.

A method for screening compounds for their ability to interact with transmembrane proteins is provided. Also provided is a method for determining whether proteins such as transmembrane proteins are able to oligomerise.

The present invention relates to a method for identifying endogenous first responder protein-cysteines. Methods for screening candidate compounds suitable for regulating NF-kB signaling and the DNA damage response pathway are also disclosed.