Conformational Studies on Calcium Binding By tBoc-Leu-Pro-Tyr-Ala-NHCH3, a Tyrosine Kinase Substrate, in a Nonpolar Solvent

With a view to understanding the structural requirement for tyrosine phosphorylation, we have examined the free and Ca(2+)-bound conformations of the synthetic peptide tBoc-Leu-Pro-Tyr-Ala-NHCH3, a substrate for a protein tyrosine kinase, using circular dichroism (CD), 1H and 13C nuclear magnetic resonance (NMR) and molecular modeling methods. CD spectrum of the free peptide in water showed a random coil structure, while the spectrum in …