A novel approach to serine protease inhibition: kinetic characterization of inhibitors whose potencies and selectivities are dramatically enhanced by Zinc(II).
Serine proteases play a role in a variety of disease states and thus are attractive targets for therapeutic intervention. We report the kinetic characterization of a class of serine protease inhibitors whose potencies and selectivities are dramatically enhanced in the presence of Zn(II). The structural basis for Zn(II)-mediated inhibition of trypsin-like proteases has recently been reported [Katz, B. A., Clark, J. M., Finer-Moore, J. S., Jenkins, T. E., Johnson, C. R., Ross, M. J., Luong, C., Moore, W. R., and Stroud, R. M. (1998) Nature 391, 608-612]. A case study of the kinetic behavior of human tryptase inhibitors is provided to illustrate the general phenomenon of Zn(II)-mediated inhibition. Tryptase, Zn(II), and the inhibitor form a ternary complex which exhibits classic tight-binding inhibition. The half-life for release of inhibitor from the tryptase-Zn(II)-inhibitor complex has been measured for a number of inhibitors. Consistent with tight-binding behavior, potent tryptase inhibitors are characterized by extremely slow rates of dissociation from the ternary complex with half-lives on the order of hours. A model of human serum, designed to reproduce physiological levels of Zn(II), has been employed to evaluate the performance of Zn(II)-potentiated tryptase inhibitors under physiological conditions. We demonstrate that Zn(II)-mediated inhibition can be achieved at physiological Zn(II) levels.
Janc
J W
JW
Axys Pharmaceuticals, 180 Kimball Way, South San Francisco, California 94080, USA. james_janc@axyspharm.com
Clark
J M
JM
Warne
R L
RL
Elrod
K C
KC
Katz
B A
BA
Moore
W R
WR
D002413:Cations, Divalent / Q000378:metabolism / Q000494:pharmacology; D053818:Chymases; D004357:Drug Synergism; D004492:Edetic Acid / Q000378:metabolism / Q000494:pharmacology; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008670:Metals / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding; D012697:Serine Endopeptidases / Q000378:metabolism*; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D012709:Serum Albumin / Q000378:metabolism; D013379:Substrate Specificity; D013816:Thermodynamics; D053802:Tryptases; D015032:Zinc / Q000378:metabolism / Q000494:pharmacology*
D002413:Cations, Divalent; D008670:Metals; D015842:Serine Proteinase Inhibitors; D012709:Serum Albumin; D004492:Edetic Acid; D012697:Serine Endopeptidases; C083294:chymase 2; D053818:Chymases; D053802:Tryptases; D015032:Zinc