Protein separation techniques are methods used to isolate specific proteins from complex mixtures, such as cell lysates or biological fluids. Common techniques include gel electrophoresis, which separates proteins based on size, and chromatography, which separates proteins based on their chemical properties. These methods are essential for studying protein function and structure. Another important technique is affinity chromatography, where proteins are separated based on their specific interactions with ligands attached to a solid support. Additionally, ultrafiltration can concentrate proteins by using membranes that allow smaller molecules to pass through while retaining larger proteins. These techniques are crucial in research and biotechnology.