title: Peptidyl aldehydes as reversible covalent inhibitors of SRC homology 2 domains.
abstract: Src homology 2 (SH2) domains are phosphotyrosine- (pY-) binding modules found in a variety of signal-transducing proteins and constitute an important class of drug targets for the treatment of signaling related diseases/conditions. To date, a large number of peptidic as well as nonpeptidic SH2 domain inhibitors have been reported. However, all of these inhibitors contain a negatively charged pY mimetic as the core structure and generally have poor membrane permeability. We report here that peptidyl cinnamaldehydes function as reversible, slow-binding inhibitors toward the SH2 domains of protein tyrosine phosphatase SHP-1. Specific interactions between the SH2 domains and the aldehydes were assessed by their ability to relieve the autoinhibitory effect of the N-terminal SH2 domain on SHP-1 catalytic activity and the surface plasmon resonance technique. The most potent inhibitor (Cinn-GEE) displayed a K(D) value of 1.3 microM against the N-terminal SH2 domain of SHP-1. The mechanism of inhibition was investigated by site-directed mutagenesis and by using Cinn-GEE specifically labeled with (13)C at the aldehyde carbon and (1)H-(13)C heteronuclear single-quantum coherence spectroscopy. The proposed mechanism involves the formation of an initial noncovalent E.I complex, which is slowly converted into a covalent imine/enamine adduct (E.I) between the aldehyde group of the inhibitor and the guanidine group of Arg betaB5 in the pY-binding pocket of the SH2 domains. These aldehydes should provide a general, neutral pharmacophore for the further development of potent, specific, and membrane-permeable SH2 domain inhibitors.
authors.affiliation: Department of Chemistry and Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
authors.forename: Junguk
authors.initials: J
authors.lastname: Park
authors.forename: Hua
authors.initials: H
authors.lastname: Fu
authors.forename: Dehua
authors.initials: D
authors.lastname: Pei
mesh_terms: D000447:Aldehydes / Q000494:pharmacology; D001120:Arginine; D001665:Binding Sites; D020134:Catalytic Domain; D003001:Cloning, Molecular; D004926:Escherichia coli; D005982:Glutathione Transferase / Q000737:chemistry; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008970:Molecular Weight; D010455:Peptides / Q000494:pharmacology*; D019000:Phosphotyrosine; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D018909:src Homology Domains
chemical_list: D000447:Aldehydes; D047908:Intracellular Signaling Peptides and Proteins; D010455:Peptides; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D001120:Arginine; D005982:Glutathione Transferase; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases