ANTILEUKOPROTEASE IN PSORIATIC SCALES

Antileukoprotease is known to be an antiproteolytic compound of mucous secretions in humans. While searching for peptide-like inhibitors of neutrophil-derived serine proteases in horny layers of human skin, we isolated a potent inhibitor of human leukocyte elastase(EC 3.4.21.37) and cathepsin G (EC 3.4.21 20 from psoriatic scales. This inhibitor sh owed inhibitory constants for human leukocyte elastase of approximatel y 0.5-2 X 10(-10) M and for cathepsin G of 2-4 X 10(-9) N. The N-termi nal amino acid sequence of the purified peptide matched the sequence o f antileukoprotease and both peptides showed the same M(r) on SDS-PAGE . Therefore, antileukoprotease may not only regulate serine protease a ctivities in mucous secretions, but also in skin.