Purification and SDS-PAGE analysis of human neutrophil gelatinase B.

Natural gelatinase B, purified from human neutrophils, occurs in 3 different forms: monomers, disulfide-linked homodimers, and NGAL–gelatinase B complexes.32 Nonreducing SDS-PAGE and Coomassie blue staining before (lane 2) and after (lane 3) removal of the NGAL–gelatinase B complex allows visualization of the positions of the monomers, the dimers, and the NGAL–gelatinase B complexes. After chemical reduction with β-mercaptoethanol, the dimer was dissociated into monomers in the electrophoretically pure preparation (lane 4). Relative molecular masses of the monomer, heterodimer, and homodimer were estimated to be 91, 125 and greater than 200 kd by comparison with the molecular mass markers (lane 1).