Isotope-labeled vibrational circular dichroism studies of calmodulin and its interactions with ligands.
In this work we have studied ligand-induced secondary structure changes in the small calcium regulatory protein calmodulin (CaM) using vibrational circular dichroism (VCD) spectroscopy. We find that, due to its chiral sensitivity, VCD spectroscopy has increased ability over IR spectroscopy to detect changes in the structure and flexibility of secondary structure elements upon ligand binding. Moreover, we demonstrate that the uniform isotope labeling of CaM with (13)C shifts its amide I' VCD band by about approximately 43 cm(-1) to lower wavenumbers, which opens up a spectral window to simultaneously visualize a bound target protein. Therefore this study also provides the first example of how isotope labeling enables protein-protein interactions to be studied by VCD with good separation of the signals for both isotope-labeled and unlabeled proteins.
Pandyra
Aleksandra A
AA
Department of Chemistry, University of Calgary, Alberta, Canada.
Yamniuk
Aaron P
AP
Andrushchenko
Valery V
VV
Wieser
Helmut
H
Vogel
Hans J
HJ
D001234:Aspergillus niger / Q000378:metabolism; D001704:Biopolymers / Q000737:chemistry*; D002147:Calmodulin / Q000737:chemistry*; D002942:Circular Dichroism / Q000379:methods*; D004583:Electrons; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D007781:Lactoferrin / Q000737:chemistry; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared
D001704:Biopolymers; D002147:Calmodulin; D008024:Ligands; D007781:Lactoferrin