Synthesis and evaluation of phosphopeptides containing iminodiacetate groups as binding ligands of the Src SH2 domain |
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Authors: | Guofeng Ye Aaron D Schuler Yousef Ahmadibeni Joel R Morgan Absar Faruqui Kezhen Huang Gongqin Sun John A Zebala Keykavous Parang |
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Institution: | aDepartment of Biomedical and Pharmaceutical Sciences, University of Rhode Island, Kingston, RI 02881, USA;bSyntrix Biosystems, Inc., Auburn, WA 98001, USA;cDepartment of Cell and Molecular Biology, University of Rhode Island, Kingston, RI 02881, USA;dDepartment of Laboratory Medicine, University of Washington, Seattle, WA 98105, USA |
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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 (Kd = 0.6 μM) to the Src SH2 domain when compared with Ac-pYEEI (Kd = 1.7 μM), an optimal Src SH2 domain ligand, and peptides 2–4 (Kd = 2.9–52.7 μM). The binding affinity of peptide 1 to the SH2 domain was reduced by more than 2-fold (Kd = 1.6 μM) upon addition of Ni2+ (300 μM), possibly due to modest structural effect of Ni2+ on the protein as shown by circular dichroism experimental results. The binding affinity of 1 was restored in the presence of EDTA (300 μM) (Kd = 0.79 μM). These studies suggest that peptides containing IDA groups may be used for designing novel SH2 domain binding ligands. |
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Keywords: | Phosphopeptides Metal chelation Iminodiacetate group SH2 domain UV titration Fluorescence polarization Circular dichroism |
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