CAPS buffer [3-(cyclohexylamino)-1-propanesulfonic acid] is a zwitterionic Good’s buffer formulated for use under strongly alkaline conditions. With an effective buffering range of approximately pH 9.7 to 11.1, this 0.5 M solution at pH 11.0 provides reliable pH control for a variety of biochemical applications. It is commonly employed in protein crystallization studies, enzyme-based assays, and Western or immunoblotting workflows. CAPS buffer is particularly advantageous for the efficient transfer of high–molecular weight proteins from SDS-PAGE gels to nitrocellulose membranes and is also suitable for use in protein sequencing procedures.