Synthetic peptide analogs of skeletal troponin C: Fluorescence studies of analogs of the low-affinity calcium-binding site II

Panos Kanellis, Jessie Yang, Herbert C. Cheung, Robert E. Lenkinski

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

Two 12-residue peptides were synthesized by the solid-phase method as structural analogs of a Ca2+-binding loop of rabbit skeletal troponin C. The sequence of the analogs corresponds to the binding loop of the Ca2+-specific low affinity binding site II (residues 63-74) but with two amino acid substitutions. In one analog, Phe-72 was replaced by tyrosine. In the other Gly-66 was substituted by serine and Phe-72 by tyrosine. The intrinsic fluorescence of the peptides was enhanced upon addition of Tb3+ or large excess of Ca2+. From the enhancement of Tb3+ emission association constants in the range (2-3) × 105m-1 and a binding stoichiometry of 1 were determined for Tb3+ binding to the peptides. Large excess of Ca2+ displaced Tb3+ from the Tb3+-peptide complexes and from these results apparent stability constants of 500-700 m-1 were deduced for Ca2+ binding. Preliminary proton nuclear magnetic resonance results on one of the peptides indicated that La3+ induced considerable perturbation of the amide proton resonances of several residues, including the aspartate at position 3, the tyrosine at position 10, and the two glutamates at the C-terminus. The results suggest involvement of these residues in cation coordination.

Original languageEnglish (US)
Pages (from-to)530-540
Number of pages11
JournalArchives of Biochemistry and Biophysics
Volume220
Issue number2
DOIs
StatePublished - Feb 1 1983

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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