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A series of phosphinic acid-containing peptide inhibitors of human stromelysin-1 (MMP-3) were prepared. The P1 through P3 subsites were varied in a systematic manner on analogs possessing an invariant P1′-P3′ segment. The in vitro activity of these compounds as inhibitors of stromelysin and collagenase is discussed.

An extensive study of the requirements for effective binding of N-carboxyalkyl peptides to human stromelysin, collagenase, and to a lesser extent, gelatinase A has been investigated. These efforts afforded inhibitors generally in the 100-400 nM range for these matrix metalloproteinases. The most significant increase in potency was obtained with the introduction of a beta-phenylethyl group at the P1' position, suggesting a small hydrophobic channel into the S1' subsite of stromelysin. One particular compound, N-[1(R)-carboxyethyl]-alpha(S)-(2-phenylethyl)glycyl-L-leucine,N- phenylamide (79a), is relatively selective for rabbit stromelysin with a K(i) = 6.5 nM and may prove useful for elucidating the role of endogenously-produced stromelysin in lapine models of tissue degradation.

We have investigated the inhibition of the human matrix metalloproteinase stromelysin (SLN) by the peptide phosphonamidate, phthaloyl-N-(CH2)4-P(O2-)-Ile-(beta-naphthyl)Ala-NH-CH3, and find that it is a potent, slow-binding inhibitor of SLN with kon = 2.7 x 10(4) M-1 sec-1, koff = 1.9 x 10(-4) sec-1, and Ki = 7 nM (pH 5.0, 25 degrees C). To probe the mechanism of inhibition, we determined pH-dependencies and solvent deuterium isotope effects. pH-dependencies of the kinetic parameters for inhibition are complex but reflect greater inhibitory potency at lower pH and suggest a mechanism for inhibition that involves the same active site groups as are involved in catalysis. The solvent isotope on kon (kon, H2O/Kon,D2O) is normal and equals 1.5 +/- 0.1. Together with the pH-dependence of inhibition, this value suggests that kon is rate-limited by a process that involves general-acid/general-base catalysis. We propose that kon is rate-limited by general-acid catalyzed ligand exchange of inhibitor for the zinc-bound water molecule.