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25 Mg NMR Relaxation Study of Mg 2+ ‐ATP Complexation in Solutions
Author(s) -
Shien ZhiShian,
Luo TzyJiun,
Hwang LianPin
Publication year - 1999
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199900104
Subject(s) - chemistry , dissociation (chemistry) , coupling constant , analytical chemistry (journal) , ion , reaction rate constant , relaxation (psychology) , kinetic energy , activation energy , kinetics , chromatography , organic chemistry , psychology , social psychology , physics , particle physics , quantum mechanics
25 Mg NMR relaxation has been applied to characterize the kinetic and dynamic parameters in the complexation process of the Mg 2+ ion with adenosine triphosphate. A modified linear prediction with singular value decomposition method developed earlier is used to obtain the preliminary chemical shift separation between the free 25 Mg 2+ ion and the 25 Mg 2+ ‐ATP complex. Then the 25 Mg 2+ NMR null point spectra is invoked to find the chemical shift separation and the quadrupolar coupling constant of the complex. With the knowledge of those parameters, T 1 and line width data at 30.62 MHz and 18.37 MHz can be analyzed to determine the correlation times for the fluctuation of electric field gradient at 25 Mg and the dissociation rate constants of the complex at the temperature range of 270–320 K. An activation energy of 8.8 kcal/mol for dissociation rate constant is obtained. It is also found that the reorientational motion of the 25 Mg 2+ ‐ATP complex is not significantly affected by the formation of ATP aggregates. A similar conclusion is further obtained by comparing the T 1 data of β‐ 31 P in ATP and Mg 2+ ‐ATP solutions.