Multi-angle light scattering as a process analytical technology measuring real-time molecular weight for downstream process control.

For many protein therapeutics including monoclonal antibodies, aggregate removal process can be complex and challenging. We evaluated two different process analytical technology (PAT) applications that couple a purification unit performing preparative hydrophobic interaction chromatography (HIC) to a multi-angle light scattering (MALS) system. Using first principle measurements, the MALS detector calculates weight-average molar mass, M and can control aggregate levels in purification.

The VieB auxiliary protein negatively regulates the VieSA signal transduction system in Vibrio cholerae.

Background: Vibrio cholerae is a facultative pathogen that lives in the aquatic environment and the human host. The ability of V. cholerae to monitor environmental changes as it transitions between these diverse environments is vital to its pathogenic lifestyle.

Calcium-dependent stoichiometries of the KCa2.2 (SK) intracellular domain/calmodulin complex in solution.

Ca(2+) activates SK Ca(2+)-activated K(+) channels through the protein Ca(2+) sensor, calmodulin (CaM). To understand how SK channels operate, it is necessary to determine how Ca(2+) regulates CaM binding to its target on SK. Tagless, recombinant SK peptide (SKp), was purified for binding studies with CaM at low and high Ca(2+) concentrations.

Bacterial display enables efficient and quantitative peptide affinity maturation.

A quantitative screening method was developed to enable isolation and affinity maturation of peptide ligands specific for a given target from peptide libraries displayed on the outer surface of Escherichia coli using multi-parameter flow cytometry. From a large, random 15-mer peptide library, screening identified a core motif of W-E/D-W-E/D that conferred binding to vascular endothelial growth factor (VEGF). One cycle of affinity maturation resulted in the identification of several families of VEGF-binding peptides having distinct consensus sequences, from which a preferred disulfide constraint emerged.

Multitarget dielectrophoresis activated cell sorter.

The ability to rapidly and efficiently isolate specific viruses, bacteria, or mammalian cells from complex mixtures lies at the heart of biomedical applications ranging from in vitro diagnostics to cell transplantation therapies. Unfortunately, many current selection methods for cell separation, such as magnetic activated cell sorting (MACS), only allow the binary separation of target cells that have been labeled via a single parameter (e.g.

Microfluidic protein detection through genetically engineered bacterial cells.

Protein microarray technology, in which a large number of capture ligands are spatially arrayed at a high density, presents an attractive method for high-throughput proteomic analysis. Toward this end, we demonstrate the first cell-based protein detection in a microsystem, wherein Escherichia coli cells are genetically engineered to express the desired capture proteins on the membrane surface and are spatially arrayed as sensing elements in a microfluidic device. An E.