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Differentiated analysis of the secondary structure of hydrophilic and hydrophobic regions in α‐ and β‐subunits of Na + ,K + ‐ATPase by Raman spectroscopy
Author(s) -
Ovchinnikov Yu.A.,
Arystarkhova E.A.,
Arzamazova N.M.,
Dzhandzhugazyan K.N.,
Efremov R.G.,
Nabiev I.R.,
Modyanov N.N.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80905-0
Subject(s) - antiparallel (mathematics) , chemistry , crystallography , protein subunit , transmembrane domain , transmembrane protein , protein secondary structure , membrane , helix (gastropod) , raman spectroscopy , hydrophobic effect , atpase , tetramer , enzyme , stereochemistry , biochemistry , biology , ecology , physics , receptor , quantum mechanics , snail , magnetic field , gene , optics
Raman spectra of active Na + ,K + ‐ATPase from pig kidney and membrane‐bound products of its two‐stage trypsinolysis, including α‐subunit hydrophobic regions as well as the intact β‐subunit and hydrophobic regions of α‐ and β‐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 α‐helical conformation; (ii) essential contents of the α‐helix as well as β‐sheet are estimated to form the hydrophilic (mainly cytoplasmic) domain of the Na + ,K + ‐ATPase α‐subunit; (iii) the exoplasmic hydrophilic domain of the β‐subunit is shown to include several antiparallel β‐pleated sheets and a small amount of the α‐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.