The disclosure provides compositions comprising at least one assembly comprising a peptide and a major histocompatibility complex (MHC), wherein the peptide is an integral component of the MHC, wherein the peptide is attached to a surface at its C-terminus through a linker and wherein the peptide is synthesized on the surface. In certain embodiments, the compositions comprise a plurality of assemblies in a spatially-ordered array. The disclosure provides methods for making and using these compositions.

Disclosed are compositions and methods for the multiplexed analysis of one or more intracellular targets of a single cell. Exemplary compositions of the disclosure comprise a surface comprising a plurality of capture agents operatively-linked thereto, wherein each capture agent specifically binds to a distinct intracellular target and wherein the plurality of capture agents form a repeating pattern; a substrate comprising a plurality of chambers, wherein the substrate releasably couples with the surface and wherein each chamber of the plurality of chambers comprises at least one repeat of the repeating pattern of the plurality of capture agents of the surface; a coating composition comprising a cell lysis composition; and a linker composition comprising a functionalization component and an extension component.

Disclosed herein, inter alia, are compositions and methods of use thereof for interrogating a cell.

The present invention generally pertains to methods of preventing disulfide scrambling in non-reducing liquid chromatography-mass spectrometry analysis of a protein of interest. In particular, the present invention pertains to the addition of cystamine to a non-reducing liquid chromatography-mass spectrometry analysis of an antibody to prevent disulfide scrambling.

A sample preparation workflow to facilitate deep N-glycomics analysis of human serum by capillary electrophoresis with laser induced fluorescence (CE-LIF) detection accommodates the higher sample concentration requirement of electrospray ionization mass spectrometry connected to capillary electrophoresis (CE-ESI-MS). A temperature gradient denaturing protocol is applied on amine functionalized magnetic bead partitioned glycoproteins to avoid precipitation. This also results in the free sugar content of the serum being significantly decreased which allows PNGase F mediated release of the N-linked carbohydrates. The liberated oligosaccharides were tagged with aminopyrene-trisulfonate, utilizing a modified evaporative labeling protocol. This workflow provides appropriate amounts of material for example for use in CE-ESI-MS analysis in negative ionization mode.

The present invention concerns a method for identifying and using a biomarker, or creating a proteome profile, indicative of a reduced response to a drug in a patient involving a thermal shift assay on a sample. The method comprises the steps of a) heating a sample from a patient b) separating soluble from insoluble protein, c) analysing either or both the soluble and insoluble protein fractions of step b) to determine the melting temperature.

The state of protein phosphorylation and glycosylation can be key determinants of cellular physiology such as early stage cancer, but the development of phosphoproteins and/or glycoproteins in biofluids for disease diagnosis remains elusive. Here we demonstrate, for the first time, a strategy to isolate and identify phosphoproteins/glycoproteins in extracellular vesicles (EVs) from human plasma as potential markers to differentiate disease from healthy states. We identified close to 10,000 unique phosphopeptides in EVs by isolating from small volume of plasma samples. Using label-free quantitative phosphoproteomics, we identified 144 phosphoproteins in plasma EVs that are significantly higher in patients diagnosed with breast cancer than in healthy controls. Several novel biomarkers were validated in individual patients using Paralleled Reaction Monitoring for targeted quantitation. Similarly a group of glycoproteins in plasma EVs are identified. The study demonstrated that the development of phosphoproteins and/or glycoproteins in plasma EV as disease biomarkers is highly feasible and may transform cancer screening and monitoring.

The present invention generally pertains to methods of detecting host cell proteins. In particular, the present invention pertains to the use of a novel activity-based protein profiling probe to identify host cell proteins with lipase activity in a pharmaceutical formulation.

Disclosed herein is a chemo-proteomic probe for labelling and monitoring a live microbe interacting with a host cell and for qualitative and quantitative analyses of those proteins involved during a microbe infects the host cell. This probe comprises a functional group for conjugating to a surface protein of a live microbe under a physiological condition; a photo-reactive group for covalent cross-linking to an interacting cell protein of a host; and a tag for isolating the cross-linked complex of the surface protein of said live microbe and the interacting protein of a host cell for qualitative and quantitative proteomics analyses. The probe may further comprise a visualization tag. This technology takes advantage of the high throughput feature of mass spectrometry analysis and combines it with a uniquely designed chemistry to achieve high efficient isolation and analysis of host cell proteins interacting with a pathogen at different stages of an infection.

Some embodiments disclosed herein provide a plurality of compositions each comprising a protein binding reagent conjugated with an oligonucleotide. The oligonucleotide comprises a unique identifier for the protein binding reagent it is conjugated with, and the protein binding reagent is capable of specifically binding to a protein target. Further disclosed are methods and kits for quantitative analysis of a plurality of protein targets in a sample and for simultaneous quantitative analysis of protein and nucleic acid targets in a sample. Also disclosed herein are systems and methods for preparing a labeled biomolecule reagent, including a labeled biomolecule agent comprising a protein binding reagent conjugated with an oligonucleotide.