Fluorescent Reporter-Based Fiber Optic Probe for Continuous Detection of Antibodies.

Measurement of antibody and antibody fusion protein concentration is vital for process development and manufacturing. Continuous, in-line monitoring of antibody concentration could be useful in a variety of applications, such as controlling the loading of protein A columns to prevent breakthrough, monitoring bioreactor titer, and detecting leaks past ultrafiltration/diafiltration membranes. Molecule-specific monitoring techniques are advantageous for antibody detection in cell culture fluid in the presence of complex process impurities.

Expression and Characterization of Intein-Cyclized Trimer of Protein A Domain Z.

protein A (SpA) is an IgG Fc-binding virulence factor that is widely used in antibody purification and as a scaffold to develop affinity molecules. A cyclized SpA Z domain could offer exopeptidase resistance, reduced chromatographic ligand leaching after single-site endopeptidase cleavage, and enhanced IgG binding properties by preorganization, potentially reducing conformational entropy loss upon binding. In this work, a Z domain trimer (Z3) was cyclized using protein intein splicing.