title: Design and evaluation of benzophenone-containing conformationally constrained ligands as tools for photoaffinity scanning of the integrin alphaVbeta3-ligand bimolecular interaction.
abstract: Integrins are cell-surface adhesion molecules involved in mediating cell-extracellular matrix interactions. High-resolution structural data are not available for these heterodimeric receptors. In order to generate tools for photoaffinity scanning of the RGD-binding site of human integrin alphaVbeta3. new conformationally constrained ligands were designed. The ligands were based on five different cyclic peptidic or peptidomimetic scaffolds with high affinity for alphaVbeta3. A single photoreactive group (a benzophenone moiety) was introduced at different positions relative to the RGD triad. In addition, an 125I or a biotin group was introduced as a reporting tag. Twenty-four cyclic ligands were prepared and their binding affinity for alphaVbeta3 was determined. In most cases, the modifications resulted in a 5- to 500-fold decrease in affinity relative to the unmodified scaffold. Analogs representing three of the five families were screened for their cross-linking efficiency. Ligands with submicromolar affinities cross-linked efficiently and specifically to the integrin receptor, whereas ligands with weaker affinities gave specific cross-linking, but with lower efficiency. Almost all of the screened ligands cross-linked predominantly to the beta3 subunit.
authors.affiliation: Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA.
authors.forename: G
authors.initials: G
authors.lastname: Bitan
authors.forename: L
authors.initials: L
authors.lastname: Scheibler
authors.forename: H
authors.initials: H
authors.lastname: Teng
authors.forename: M
authors.initials: M
authors.lastname: Rosenblatt
authors.forename: M
authors.initials: M
authors.lastname: Chorev
mesh_terms: D001577:Benzophenones / Q000138:chemical synthesis*; D001665:Binding Sites; D001667:Binding, Competitive; D002460:Cell Line; D003432:Cross-Linking Reagents / Q000138:chemical synthesis; D006801:Humans; D007457:Iodine Radioisotopes; D008024:Ligands; D013058:Mass Spectrometry; D008968:Molecular Conformation; D015394:Molecular Structure; D009842:Oligopeptides / Q000138:chemical synthesis; D010456:Peptides, Cyclic / Q000138:chemical synthesis*; D019920:Photoaffinity Labels / Q000138:chemical synthesis*; D019030:Receptors, Vitronectin / Q000378:metabolism*
chemical_list: D001577:Benzophenones; D003432:Cross-Linking Reagents; D007457:Iodine Radioisotopes; D008024:Ligands; D009842:Oligopeptides; D010456:Peptides, Cyclic; D019920:Photoaffinity Labels; D019030:Receptors, Vitronectin; C047981:arginyl-glycyl-aspartic acid