Binding of a new Ca2+ sensitizer, levosimendan, to recombinant human cardiac troponin C. A molecular modelling, fluorescence probe, and proton nuclear magnetic resonance study.
The binding of a new calcium sensitizer, levosimendan, to human cardiac troponin C (cTnC) is described. Fluorescence studies done on dansylated recombinant human cTnC and a site-directed mutant showed that levosimendan modulated the calcium-induced conformational change in cTnC, and revealed the role of Asp-88 in the binding of the drug to the NH2-terminal domain of cTnC. Furthermore, NMR studies performed on the NH2-terminal fragment of cTnC showed a spatial proximity between levosimendan and Met81, Met85, and Phe77 in the drug-protein complex. These data were used to build an optimized model of the drug-protein complex, in which levosimendan binds cTnC at the hydrophobic pocket of the NH2-terminal domain. The role of the binding of levosimendan to cTnC in the pharmacological action of this drug in vivo is discussed.
Orion Corp., Orion-Farmos, Orion Research, Espoo, Finland.
P
P
Pollesello
M
M
Ovaska
J
J
Kaivola
C
C
Tilgmann
K
K
Lundström
N
N
Kalkkinen
I
I
Ulmanen
E
E
Nissinen
J
J
Taskinen
D001483:Base Sequence; D002118:Calcium / Q000378:metabolism*; D002316:Cardiotonic Agents / Q000378:metabolism*; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics; D005456:Fluorescent Dyes; D006801:Humans; D006835:Hydrazones / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D011485:Protein Binding; D011522:Protons; D011724:Pyridazines / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D000077464:Simendan; D014336:Troponin / Q000235:genetics / Q000378:metabolism*; D019209:Troponin C
D002316:Cardiotonic Agents; D017931:DNA Primers; D005456:Fluorescent Dyes; D006835:Hydrazones; D011522:Protons; D011724:Pyridazines; D011994:Recombinant Proteins; D014336:Troponin; D019209:Troponin C; D000077464:Simendan; D002118:Calcium