Open AccessDifference between the E1 and E2 conformations of gastric H + /K + ‐ATPase in a multilamellar lipid film system
Author(s) -
Stricht Delphine Vander,
Raussens Vincent,
Oberg Keith A.,
Ruysschaert JeanMarie,
Goormaghtigh Erik
Publication year - 2001
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2001.02173.x
Subject(s) - conformational change , chemistry , fluorescein isothiocyanate , ion , fourier transform infrared spectroscopy , atpase , amino acid , crystallography , molecule , attenuated total reflection , fluorescein , analytical chemistry (journal) , fluorescence , infrared spectroscopy , stereochemistry , biophysics , biochemistry , chromatography , enzyme , organic chemistry , biology , physics , quantum mechanics
A liquid flow cell was used for an attenuated total reflection‐Fourier transform infrared spectroscopy (ATR‐FTIR) study of conformational changes taking place in the gastric H + /K + ‐ATPase. Shifting from E1 to E2 form is induced by replacing Na + by K + ions. Introducing ions through a flow passing over a protein multilayer film induced the conformational change without cell manipulations. Measurement sensitivity was thereby improved by about one order of magnitude. The detection threshold allowed the possibility to detect a change affecting five amino acids out of the 1324 that compose the H + /K + ‐ATPase molecule. It appeared that fewer than five amino‐acid residues undergo a conformational change upon replacing Na + by K + ions in the medium. Evidence that conformational changes occur in an identical system was brought by monitoring the fluorescence of fluorescein isothiocyanate‐labeled H + /K + ‐ATPase in similar conditions. Our data suggest that essentially the tertiary structure of the protein is modified.