Binding of monovalent cations induces large changes in the secondary structure of Na+,K+-ATPase as probed by Raman spectroscopy.
Raman spectra of active Na+,K+-ATPase from pig kidney in media containing Na+ (E1), K+ (E2) or without exogenous ions (E1 conformation) were recorded in order to calculate the changes in the enzyme's secondary structure induced by binding of monovalent cations. It is demonstrated that: (i) K+ binding to the E1 form of the enzyme leads to conversion of approximately 100 peptide groups from the beta-structure to alpha-helical conformation; (ii) the transition is reversible and fully reproducible in the E1----E2----E1 and E2----E1----E2 experimental schemes. Predictional calculations revealed polypeptide chain segments involved in the alpha----beta transformations. These segments reside mainly in the two highly conserved regions of the alpha-subunit in the cytoplasmic domain of Na+,K+-ATPase. A possible role for the beta-subunit is discussed.
Nabiev
I R
IR
Shemyakin Institute of Bioorganic Chemistry, USSR Academy of Sciences, Moscow.
Dzhandzhugazyan
K N
KN
Efremov
R G
RG
Modyanov
N N
NN
D000818:Animals; D011188:Potassium / Q000378:metabolism*; D011487:Protein Conformation; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013059:Spectrum Analysis, Raman
D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium