Phosphoramidate peptide inhibitors of human skin fibroblast collagenase

Article abstract of DOI:10.1021/jm00163a044

An extensive series of N-(monoethylphosphoryl)peptides was synthesized and their inhibition of purified human skin fibroblast collagenase examined. At the cleavage site S₁ all reported compounds have the (EtO)(OK)P(O) group and the peptide side chain extended toward the C-terminal end (up to P₅') 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 K(i) values in the micromolar range. The most potent of these, (EtO)(OK)P(O)-Ile-TrpNHCH₃ (68), inhibits with a K(i) value of 1.5 μM and is nearly 100 times stronger than (EtO)(OK)P(O)-Ile-Ala-GlyOK (51) (K(i) of 140 μM), which has the sequence matching that of the α₁(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 K(i) 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 K(i) of 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.