title: Synthesis and evaluation of phosphopeptides containing iminodiacetate groups as binding ligands of the Src SH2 domain.
abstract: Phosphopeptide pTyr-Glu-Glu-Ile (pYEEI) has been introduced as an optimal Src SH2 domain ligand. Peptides, Ac-K(IDA)pYEEIEK(IDA) (1), Ac-KpYEEIEK (2), Ac-K(IDA)pYEEIEK (3), and Ac-KpYEEIEK(IDA) (4), containing 0-2 iminodiacetate (IDA) groups at the N- and C-terminal lysine residues were synthesized and evaluated as the Src SH2 domain binding ligands. Fluorescence polarization assays showed that peptide 1 had a higher binding affinity (K(d) = 0.6 microM) to the Src SH2 domain when compared with Ac-pYEEI (K(d) = 1.7 microM), an optimal Src SH2 domain ligand, and peptides 2-4 (K(d) = 2.9-52.7 microM). The binding affinity of peptide 1 to the SH2 domain was reduced by more than 2-fold (K(d) = 1.6 microM) upon addition of Ni(2+) (300 microM), possibly due to modest structural effect of Ni(2+) on the protein as shown by circular dichroism experimental results. The binding affinity of 1 was restored in the presence of EDTA (300 microM) (K(d) = 0.79 microM). These studies suggest that peptides containing IDA groups may be used for designing novel SH2 domain binding ligands.
authors.affiliation: Department of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA.
authors.forename: Guofeng
authors.initials: G
authors.lastname: Ye
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Schuler
authors.forename: Yousef
authors.initials: Y
authors.lastname: Ahmadibeni
authors.forename: Joel R
authors.initials: JR
authors.lastname: Morgan
authors.forename: Absar
authors.initials: A
authors.lastname: Faruqui
authors.forename: Kezhen
authors.initials: K
authors.lastname: Huang
authors.forename: Gongqin
authors.initials: G
authors.lastname: Sun
authors.forename: John A
authors.initials: JA
authors.lastname: Zebala
authors.forename: Keykavous
authors.initials: K
authors.lastname: Parang
mesh_terms: D000595:Amino Acid Sequence; D001667:Binding, Competitive; D002942:Circular Dichroism; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes / Q000737:chemistry; D007098:Imino Acids / Q000737:chemistry*; D008024:Ligands; D010748:Phosphopeptides / Q000138:chemical synthesis* / Q000737:chemistry; D011485:Protein Binding; D018909:src Homology Domains
chemical_list: D005456:Fluorescent Dyes; D007098:Imino Acids; D008024:Ligands; D010748:Phosphopeptides; C008109:iminodiacetic acid