title: Differentiated analysis of the secondary structure of hydrophilic and hydrophobic regions in alpha- and beta-subunits of Na+,K+-ATPase by Raman spectroscopy.
abstract: 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.
authors.affiliation: Shemyakin Institute of Bioorganic Chemistry, USSR Academy of Sciences, Moscow.
authors.lastname: Ovchinnikov YuA
authors.forename: E A
authors.initials: EA
authors.lastname: Arystarkhova
authors.forename: N M
authors.initials: NM
authors.lastname: Arzamazova
authors.forename: K N
authors.initials: KN
authors.lastname: Dzhandzhugazyan
authors.forename: R G
authors.initials: RG
authors.lastname: Efremov
authors.forename: I R
authors.initials: IR
authors.lastname: Nabiev
authors.forename: N N
authors.initials: NN
authors.lastname: Modyanov
mesh_terms: 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
chemical_list: D046911:Macromolecular Substances; D014357:Trypsin; D000254:Sodium-Potassium-Exchanging ATPase