Solid phase combinatorial library of phosphinic peptides for discovery of matrix metalloproteinase inhibitors

A solid phase combinatorial library of 165 000 phosphinic peptide inhibitor s was prepared and screened for activity against MMP-12. The inhibitors of the library had the structure XXX-G Psi {PO2H-CH2}L-XXX, in which X is an a rbitrary amino acid and G Psi {PO2H-CH2}L is a Gly-Leu phosphinic dipeptide analogue. The library was constructed as a one-bead-two-compounds library so that every bead contained a common quenched fluorogenic substrate and a different putative inhibitor. In addition, the inhibitor part was prepared by ladder synthesis. After incubation with MMP-12, beads containing active inhibitors were selected, and the inhibitor sequences were recorded using M ALDI-TOF MS. Statistical analysis of the sequences obtained from 86 beads g ave rise to a consensus sequence which was resynthesized along with 20 rela ted sequences. Three truncated sequences and 16 sequences originally presen t on beads were also resynthesized. The inhibitors were investigated in an enzyme kinetic assay with MMP-12 showing that the compounds derived from th e consensus sequence were strong inhibitors with Ki values down to 6 nM, wh ereas the sequences originally present on beads varied in potency with Ki v alues from micromolar to nanomolar. Truncated sequences derived from the co nsensus sequence were poor inhibitors of MMP-12.