Purification of cysteine-rich bioactive peptides from leukocytes by continuous acid-urea-polyacrylamide gel electrophoresis.

A new continuous acid-urea-polyacrylamide gel electrophoresis (CAU-PAGE) preparative method was developed and used to purify rabbit and human defensins. With it, we identified two post-translationally modified forms of rabbit defensins NP-1 and NP-2, and purified a processed RANTES (beta-intercrine) peptide from leukophoresed human leukocytes. CAU-PAGE afforded approximately 70% recovery of rabbit defensin NP-5. The recovered defensins were not N-terminally modified, and their in vitro antimicrobial activity was equivalent to that of defensins purified by previously described chromatographic methods. Since CAU-PAGE is performed under nonreducing conditions, it should be especially useful for purifying cationic peptides with intramolecular disulfide bonds, such as defensins and alpha or beta-intercrines.