Abstract: This invention relates to a method for measuring viscosity of a fluid using particle diffusometry (PD). The method finds practical applications in detecting structural and functional changes of a biomolecular composition by comparing the viscosity change as compared with the standard of the biomolecular composition. This method may also find uses in clinical diagnosis and quality control of clinical biological medicines, food and feeds during the process of manufacturing, distribution and consumption.

Abstract: A radical departure from the classical E1-E2-E3 three-enzyme mediated ubiquitination of eukaryotes, the bacterial enzymes of the SidE family of Legionella pneumophila effectors utilize NAD+ to ligate ubiquitin onto target substrate proteins achieved via a two-step mechanism involving (1) ADP-ribosylation of ubiquitin followed by (2) phosphotransfer to a target serine residue. Using fluorescent NAD+ analogues as well as synthetic substrate mimics, a continuous assay system enabling real-time monitoring of both steps of this mechanism is disclosed herein. These assays are amenable to biochemical studies and high-throughput screening of inhibitors of these effectors, and enable the discovery and characterization of putative enzymes similar to the SidE family in other organisms.

Abstract: Methods and systems suitable for tracking Brownian motion of particles suspended in a fluid and determining the diffusion coefficient of the particles therefrom in order to characterize the particles, their synthesis, and/or their surface modifications. The methods include providing a sample having particles suspended in a fluid, obtaining and recording at least first and second images of the sample wherein the first image obtained at a first time and the second image subsequently obtained at a second time, determining the average displacement of the particles in an area of the first and second images during a time period between the first time and the second time based on the first and second images, and then determining a diffusion coefficient of the particles in the area of the first and second images based on the average displacement of the particles during the time period.

Abstract: Methods and systems suitable for tracking Brownian motion of particles suspended in a fluid and determining the diffusion coefficient of the particles therefrom in order to characterize the particles, their synthesis, and/or their surface modifications. The methods include providing a sample having particles suspended in a fluid, obtaining and recording at least first and second images of the sample wherein the first image obtained at a first time and the second image subsequently obtained at a second time, determining the average displacement of the particles in an area of the first and second images during a time period between the first time and the second time based on the first and second images, and then determining a diffusion coefficient of the particles in the area of the first and second images based on the average displacement of the particles during the time period.

Abstract: This invention relates to a method for measuring viscosity of a fluid using particle diffusometry (PD). The method finds practical applications in detecting structural and functional changes of a biomolecular composition by comparing the viscosity change as compared with the standard of the biomolecular composition. This method may also find uses in clinical diagnosis and quality control of clinical biological medicines, food and feeds during the process of manufacturing, distribution and consumption.

Abstract: Disclosed herein are protein enrichment substrates and methods for making the same that can be used to enrich proteins of interest. Also disclosed herein are methods for protein purification using these protein enrichment substrates.