Open AccessQuantitative Determination of the Conformation of ATP in Aqueous Solution Using the Lanthanide Cations as Nuclear‐Magnetic‐Resonance Probes
Author(s) -
TANSWELL Paul,
THORNTON Janet M.,
KORDA Alexander V.,
WILLIAMS Robert J. P.
Publication year - 1975
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1975.tb02284.x
Subject(s) - lanthanide , chemistry , molecule , crystallography , resonance (particle physics) , aqueous solution , relaxation (psychology) , nuclear magnetic resonance spectroscopy , chemical shift , conformational change , nuclear magnetic resonance , ion , stereochemistry , social psychology , psychology , physics , organic chemistry , particle physics
Chemical shift perturbations of the eight 1 H resonances and of the three 31 P resonances in the nuclear magnetic resonance spectra of ATP in 2 H 2 O, pH 6.0, have been induced by specifically bound lanthanide cations Ln 3+ (Ln = Pr, Nd, Eu, Yb). After separation of contact (through bond) perturbations the resultant through‐space shifts, which are found to have axial symmetry, are used in an analysis of the conformation of the Ln 3+ ‐ATP complex. A computer program was used to search for the conformations of the molecule which fit the nuclear magnetic resonance data. The “best” solutions obtained represent a small closely interrelated family of conformations. Effects of the cation Gd 3+ on the longitudinal relaxation rates of five of the protons of ATP were also measured and used to confirm the conformational family. One of these conformations corresponds closely to one of the crystal structure forms, with an anti arrangement of the base‐ribose unit and a right‐hand helical phosphate chain folded towards the adenine part of the molecule. The lanthanide ion binds predominantly to the β and γ phosphates and does not interact with the purine ring, these two centres being separated by at least one water molecule.