Crystals of the urokinase type plasminogen activator variant beta c-uPA incomplex with small molecule inhibitors open the way towards structure-based drug design

Urokinase is a serine protease involved in cancer growth and metastasis. He re we present the first urokinase crystal structure in complex with reversi ble inhibitors at 2.1 and 2.6 Angstrom resolution. These inhibitor complex structures have been obtained from crystals of engineered urokinase type pl asminogen activator designed to obtain a crystal form open for inhibitor so aking. The mutant C122S loses its flexible A-chain upon activation cleavage and crystallises in the presence of benzamidine, which was later displaced by the desired inhibitor. This new soakable crystal form turned out to be of great value in the process of structure-based drug design. The evaluated binding mode of amiloride, and UKI-1D revealed a new subsite of the primar y specificity pocket of urokinase that will be employed in the future ligan d optimisation process. (C) 2000 Academic Press.