Interaction of bepridil with the cardiac troponin C/troponin I complex

FEBS Letters

Finley, Natosha¹  Sasi, Soumya¹  Rosevear, Paul R.¹  Abbott, M.Bret¹  Abusamhadneh, Ekram¹  Dvoretsky, Alex¹ 

[1]Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, College of Medicine, 231 Albert B. Sabin Way, Cincinnati, OH 45267, USA

关键词: Cardiac troponin C;    Cardiac troponin I;    Bepridil;    Nuclear magnetic resonance;    Drug binding;    cTnC;    recombinant cardiac troponin C (desMet1-Ala2;    Cys35Ser);    cTnI;    recombinant mouse cardiac troponin I;    cTnI(1–80);    cardiac troponin I corresponding to residues 1–80;   

DOI  :  10.1016/S0014-5793(01)02790-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have investigated the binding of bepridil to calcium-saturated cardiac troponin C in a cardiac troponin C/troponin I complex. Nuclear magnetic resonance spectroscopy and [¹⁵N,²H]cardiac troponin C permitted the mapping of bepridil-induced amide proton chemical shifts. A single bepridil-binding site in the regulatory domain was found with an affinity constant of ∼140 μM⁻¹. In the presence of cardiac troponin I, bepridil binding to the C domain of cardiac troponin C was not detected. The pattern of bepridil-induced chemical shifts is consistent with stabilization of more open regulatory domain conformational states. A similar pattern of chemical shift perturbations was observed for interaction of the troponin I cardiac-specific amino-terminus with the cardiac troponin C regulatory domain. These results suggest that both bepridil and the cardiac-specific amino-terminus may mediate an increase in calcium affinity by interacting with and stabilizing open regulatory domain conformations. Chemical shift mapping suggests a possible role for inactive calcium-binding site I in the modulation of calcium affinity.

【 授权许可】

Unknown