PHOSPHORAMIDATE PEPTIDE INHIBITORS OF HUMAN-SKIN FIBROBLAST COLLAGENASE

An extensive series of N-(monoethylphosphoryl)peptides was synthesized and their inhibition of purified human skin fibroblast collagenase examined. At the cleavage site S1all reported compounds have the (EtO)(OK)P(O) group and the peptide side chain extended toward the C-terminal end (up to P6') of the substrate sequence. These phosphoramidates with a tetrahedrally hybridized phosphorus atom are thought to be transition state analogue inhibitors. They exhibited fair inhibitory potency against this vertebrate collagenase having Kt values in the micromolar range. The most potent of these, (EtO)(OK)P(O)-Ile-TrpNHCH3 (68), inhibits with a K1value of 1.5 µM and is nearly 100 times stronger than (EtO)(OK)P(O)Ile-Ala-GlyOK (51) (Kiof 140 µM), which has the sequence matching that of the αi(I) chain of collagen in P1', P2', P3' after the cleavage site. Several compounds were prepared in an attempt to identify the nature of the S2', S3', and S4' binding sites. Alanine at the P2' position was replaced by leucine, phenylalanine, tryptophan, or tyrosine derivatives, resulting in Ki, values in a significantly lower range, 1.0-40 µM, compared to 51. No upper size limitation or specificity has been found at this position, yet similar replacements at the P3' position, which is occupied naturally by a glycine residue, gave weaker inhibitors: (EtO)(OK)P(O)-Ile-Tyr(OBzl)-PheOK (57) had a Kiof 120 µM. Hexapeptide derivatives had weaker activities in the 270 µM-2 mM range. All inhibitors were evaluated by using the synthetic thio peptolide spectrophotometric assay. © 1990, American Chemical Society. All rights reserved.