title: In situ assembly of enzyme inhibitors using extended tethering.
abstract: Cysteine aspartyl protease-3 (caspase-3) is a mediator of apoptosis and a therapeutic target for a wide range of diseases. Using a dynamic combinatorial technology, 'extended tethering', we identified unique nonpeptidic inhibitors for this enzyme. Extended tethering allowed the identification of ligands that bind to discrete regions of caspase-3 and also helped direct the assembly of these ligands into small-molecule inhibitors. We first designed a small-molecule 'extender' that irreversibly alkylates the cysteine residue of caspase-3 and also contains a thiol group. The modified protein was then screened against a library of disulfide-containing small-molecule fragments. Mass-spectrometry was used to identify ligands that bind noncovalently to the protein and that also form a disulfide linkage with the extender. Linking the selected fragments with binding elements from the extenders generates reversible, tight-binding molecules that are druglike and distinct from known inhibitors. One molecule derived from this approach inhibited apoptosis in cells.
authors.affiliation: Sunesis Pharmaceuticals, Inc., 341 Oyster Point Boulevard, South San Francisco, CA 94080, USA. erlanson@sunesis.com
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Erlanson
authors.forename: Joni W
authors.initials: JW
authors.lastname: Lam
authors.forename: Christian
authors.initials: C
authors.lastname: Wiesmann
authors.forename: Tinh N
authors.initials: TN
authors.lastname: Luong
authors.forename: Robert L
authors.initials: RL
authors.lastname: Simmons
authors.forename: Warren L
authors.initials: WL
authors.lastname: DeLano
authors.forename: Ingrid C
authors.initials: IC
authors.lastname: Choong
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Burdett
authors.forename: W Michael
authors.initials: WM
authors.lastname: Flanagan
authors.forename: Dennis
authors.initials: D
authors.lastname: Lee
authors.forename: Eric M
authors.initials: EM
authors.lastname: Gordon
authors.forename: Tom
authors.initials: T
authors.lastname: O'Brien
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000737:chemistry* / Q000378:metabolism; D020650:Combinatorial Chemistry Techniques / Q000379:methods*; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000145:classification / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects* / Q000378:metabolism; D013058:Mass Spectrometry / Q000379:methods; D008958:Models, Molecular; D019151:Peptide Library
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D019151:Peptide Library; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases