Premium
Na,K‐ATPase labelled with 5‐iodoacetamidofluorescein: E 2 ‐E 1 conformational transition induced by different nucleotides
Author(s) -
Lopina O.D.,
Pindel E.V.,
Boldyrev A.A.
Publication year - 1990
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(90)81510-u
Subject(s) - nucleotide , chemistry , gtp' , atpase , stereochemistry , conformational change , crystallography , molecule , purine , enzyme , biochemistry , organic chemistry , gene
A conformational transition between E 2 and E 1 forms of Na, K‐ATPase induced by different nucleotides has been studied under steady state conditions using the enzyme labelled with 5‐iodoacetamidofluorescein. In the presence of K + the plot of fluorescence as a function of [ATP], [ADP] or [CTP] (in a range of 5 μM‐12 mM) is a biphasic one. A similar dependence for AMP, ITP, GTP and UTP demonstrates a hyperbolic behaviour. The data suggest that the shift in the equilibrium between E 2 and E 1 forms of Na,K‐ATPase towards the E 1 conformation is induced by ATP binding both with high and low affinity sites. Two structural features of ATP are apparently important for its interaction with more than one type of ATP binding sites or for providing for E 2 ‐E 1 transition induced by this interaction: (i) β‐phosphate group in the terminal part of the molecule, (ii) unprotonated N 1 and/or NH 2 ‐group in the 6th position of the purine base.