Differentiated analysis of the secondary structure of hydrophilic and hydrophobic regions in alpha- and beta-subunits of Na+,K+-ATPase by Raman spectroscopy.
Raman spectra of active Na+,K+-ATPase from pig kidney and membrane-bound products of its two-stage trypsinolysis, including alpha-subunit hydrophobic regions as well as the intact beta-subunit and hydrophobic regions of alpha- and beta-subunits, were measured to calculate the secondary structure of hydrophilic and hydrophobic regions of the enzyme. Consequent comparison demonstrated unambiguously that (i) membrane-bound hydrophobic parts of polypeptide chains of Na+,K+-ATPase subunits are in the alpha-helical conformation; (ii) essential contents of the alpha-helix as well as beta-sheet are estimated to form the hydrophilic (mainly cytoplasmic) domain of the Na+,K+-ATPase alpha-subunit; (iii) the exoplasmic hydrophilic domain of the beta-subunit is shown to include several antiparallel beta-pleated sheets and a small amount of the alpha-helix and unordered conformations. The model of the secondary structure organization of hydrophilic domains as well as 8 hydrophobic transmembrane segments of the enzyme molecule was proposed on the basis of experimental results and predictional calculations.
Ovchinnikov YuA
Shemyakin Institute of Bioorganic Chemistry, USSR Academy of Sciences, Moscow.
Arystarkhova
E A
EA
Arzamazova
N M
NM
Dzhandzhugazyan
K N
KN
Efremov
R G
RG
Nabiev
I R
IR
Modyanov
N N
NN
D000818:Animals; D002462:Cell Membrane / Q000201:enzymology; D007679:Kidney Medulla / Q000201:enzymology; D046911:Macromolecular Substances; D008958:Models, Molecular; D011487:Protein Conformation; D000254:Sodium-Potassium-Exchanging ATPase; D013059:Spectrum Analysis, Raman / Q000379:methods; D013552:Swine; D014357:Trypsin
D046911:Macromolecular Substances; D014357:Trypsin; D000254:Sodium-Potassium-Exchanging ATPase