| Abstract: | Di- and tripeptides with sequences present in collagen that are known to occupy the S1' through S3' subsites at the active site of the collagenase from Clostridium histolyticum do not themselves inhibit this zinc protease. Thus glycylproline, glycylprolylalanine, and their C-terminal amides are not inhibitors. N alpha-Phosphorylglycylproline, N alpha-phosphorylglycyl-L-prolyl-L-alanine, and their C-terminal amides are weak inhibitors with IC50's (concentration causing half-maximal inhibition) of 4.6, 0.8, 3, and 1.5 mM, respectively. Extension of glycyl-L-prolyl-L-alanine to L-leucyl-glycyl-L-prolyl-L-alanine gives a tetrapeptide known to occupy the S1, S1', S2', and S3' subsites of collagenase when present in collagen but that still does not itself inhibit the enzyme. (Isoamylphosphonyl)glycyl-L-prolyl-L-alanine, a peptide containing a tetrahedral phosphorus atom at the position of the amide carbonyl carbon of the L-leucylglycyl amide bond of the parent tetrapeptide, inhibits collagenase with an IC50 of 16 microM, at least 1000-fold more potent than the parent peptide. Substitution of the two-carbon ethyl chain of alanine for the five-carbon isoamyl chain of leucine increases the IC50 to 46 microM. Substitution of the n-decyl chain for the isoamyl chain does not change the IC50. (Isoamylphosphonyl)glycyl-glycyl-L-proline contains a tripeptide that does not occupy the S1' through S3' subsites of collagenase when this peptide is present in collagen and thus has an IC50 of 4.4 mM. (Isoamylphosphonyl)glycyl-L-prolyl-L-alanine may be an analogue of the tetrahedral transition state for the hydrolysis of the natural collagen substrate.(ABSTRACT TRUNCATED AT 250 WORDS) |
