Discovery and characterization of human antibody inhibitors of pregnancy-associated plasma protein-A.

Journal Article (Journal Article)

Pregnancy-associated plasma protein-A (PAPP-A) is a metalloprotease that cleaves insulin-like growth factor-binding proteins (IGFBPs) to release bioactive levels of free insulin-like growth factor. Specific and potent inhibitors of PAPP-A may further elucidate the biological functions of this protease and could prove to be of therapeutic value. Phage display was used to discover fully human antibody inhibitors of PAPP-A activity towards IGFBP4 cleavage. Estimates of the inhibition constants for these antibodies were subsequently determined using a novel continuous assay of PAPP-A protease activity that uses an internally quenched synthetic peptide substrate (DX-1655). DX-1655 was hydrolyzed by PAPP-A with a K(m) of 33 muM and a k(cat) of 0.3 s(-1) (k(cat)/K(m)=9.1x10(3) M(-1) s(-1)). PAPP-A activity towards DX-1655 displays a bell-shaped pH profile, with pK(a) values of 8.2 and 10.8 and a maximum rate at approximately pH 9.5. Using this continuous assay, we measured apparent K(i) values of 1.7+/-0.2 and 7.4+/-1.5 nM for the F2 and D9 antibodies, respectively.

Full Text

Duke Authors

Cited Authors

  • Chen, T; Hogan, S; Conley, G; Pazmany, C; Wu, Q-L; McNeil, GL; Bassill, G; Macintyre, AN; Martik, D; Nixon, AE; Sexton, DJ

Published Date

  • May 2007

Published In

Volume / Issue

  • 388 / 5

Start / End Page

  • 507 - 512

PubMed ID

  • 17516846

International Standard Serial Number (ISSN)

  • 1431-6730

Digital Object Identifier (DOI)

  • 10.1515/BC.2007.058


  • eng

Conference Location

  • Germany