The PIPES Buffer is a zwitterionic buffering agent commonly used in biochemistry and molecular biology for its ability to maintain a stable pH. With a pKa of approximately 6.8, PIPES is effective in the pH range of 6.1 to 7.5, making it suitable for cell culture, enzyme assays, protein purification, and as a running buffer in gel electrophoresis. PIPES is also used in electron microscopy, protein crystallization, and isoelectric focusing and chromatography.