title: SAR and X-ray. A new approach combining fragment-based screening and rational drug design: application to the discovery of nanomolar inhibitors of Src SH2.
abstract: (pp60)Src is a protein involved in signal transduction and is mainly expressed in neurones, platelets, and osteoclasts. Its precise biological role was recently discovered with the KO experiments by Soriano that gave rise to no other apparent phenotype than osteopetrosis, a disease resulting in excedent bone formation. The SH2 domain of the Src family specifically recognizes a sequence of tetrapeptide featuring a phosphotyrosine and a lipophilic aminoacid at the +1 and +3 positions. Recently we engaged in the search for SH2 ligands via modular peptidomimicry of this tetrapetide. This gave rise to several families of nanomolar inhibitors; the best one incorporated a caprolactam scaffold, a biphenyl moiety, and a phosphotyrosine. However, these inhibitors still incorporated the phosphate group that confers good binding affinity to the protein. Phosphates have undesirable features for drug candidates, namely, high rate of hydrolysis of the phosphate group by phosphatases and high charge content precluding cell penetration. Therefore, while searching for optimal non-peptide ligands for Src SH2, we looked for phosphate replacements. For this, we have designed an SAR by fragment crystallography approach. The start of this work resulted from two experimental observations. First, the fact that phenyl phosphate itself displayed detectable binding affinity for Src SH2 permitted us to perform a screening of small aromatic compounds as phenyl phosphate surrogates. Second, the obtention of large Src SH2 crystals displaying a channel large enough for soaking purposes allowed structure determination of over 40 of these small aromatic compounds bound in the phosphotyrosine binding pocket. This search and the way it gave rise to low nanomolar range Src SH2 inhibitors devoid of phosphate groups will be the subject of the present paper.
authors.affiliation: Medicinal Chemistry, Central Research, Bone Disease Domain, Aventis, 102 Route de Noisy, F-93235 Romainville Cedex, France. dominique.lesuisse@aventis.com
authors.forename: Dominique
authors.initials: D
authors.lastname: Lesuisse
authors.forename: Gudrun
authors.initials: G
authors.lastname: Lange
authors.forename: Pierre
authors.initials: P
authors.lastname: Deprez
authors.forename: Didier
authors.initials: D
authors.lastname: Bénard
authors.forename: Bernard
authors.initials: B
authors.lastname: Schoot
authors.forename: Georges
authors.initials: G
authors.lastname: Delettre
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Marquette
authors.forename: Pierre
authors.initials: P
authors.lastname: Broto
authors.forename: Véronique
authors.initials: V
authors.lastname: Jean-Baptiste
authors.forename: Paulette
authors.initials: P
authors.lastname: Bichet
authors.forename: Edoardo
authors.initials: E
authors.lastname: Sarubbi
authors.forename: Eliane
authors.initials: E
authors.lastname: Mandine
mesh_terms: D018360:Crystallography, X-Ray; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000737:chemistry*; D008958:Models, Molecular; D010755:Organophosphates / Q000737:chemistry; D011485:Protein Binding; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors* / Q000737:chemistry; D013329:Structure-Activity Relationship; D018909:src Homology Domains
chemical_list: D004791:Enzyme Inhibitors; D010755:Organophosphates; D016392:Proto-Oncogene Proteins pp60(c-src)