N-terminal region (domain 1) of calmodulin is the low affinity site for Ca2+. A 13C NMR study of S-cyanocalmodulin.
A single cysteine residue (Cys-27) of wheat calmodulin was labeled with 13C by cyanylation. No change in the Ca2+ saturation pattern was observed after the cyanylation. On titration which Ca2+, the chemical shift of the 13C-label showed a downfield shift. The downfield shift was observed at Ca2+/calmodulin molar ratios between 1.8 and 3.5, while a blue shift of the UV absorption of Tyr-139 was observed between 0 and 1.7. The result indicated the domain 1 containing Cys-27 to be the low affinity site for Ca2+.
D000596:Amino Acids / Q000032:analysis; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000031:analogs & derivatives* / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy
D000596:Amino Acids; D002147:Calmodulin; C041235:S-cyanocalmodulin; D002118:Calcium