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CE with on‐line detection by ICP‐MS for studying the competitive binding of zinc against cadmium for glutathione
Author(s) -
Li Yan,
Liu JingMin,
Xia YunLong,
Jiang Yan,
Yan XiuPing
Publication year - 2008
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200800309
Subject(s) - chemistry , glutathione , zinc , enthalpy , kinetics , cadmium , reaction rate constant , non competitive inhibition , competitive binding , thermodynamics , biochemistry , organic chemistry , enzyme , physics , receptor , quantum mechanics
Development of a feasible method for studying the competitive interaction between a pair of antagonists is essential for understanding the antagonism of trace metals in biological systems. Herein, we report the application of CE on‐line coupled with ICP mass spectroscopy (CE‐ICP‐MS) to investigate the competitive binding of Zn 2+ against Cd 2+ for glutathione (GSH), which is related to the detoxification of Cd 2+ in biological system, and introduce a method to evaluate the kinetics and thermodynamics for the competitive binding of Zn 2+ against Cd 2+ for GSH. The CE‐ICP‐MS hybrid technique allows easy and sensitive probing of the competitive binding of Zn 2+ against Cd 2+ for GSH and quantitative determination of the important thermodynamic and kinetic parameters of the competitive binding of Zn 2+ against Cd 2+ for GSH. Owing to the high sensitivity and element selectivity with multi‐elements detection capacity of ICP‐MS, we detailed the evaluation of the kinetics and thermodynamics describing the competition of Zn 2+ against Cd 2+ for GSH from the systematic data obtained by CE‐ICP‐MS. The competitive binding of Zn 2+ against Cd 2+ for GSH was demonstrated exothermic and thermodynamically favorable (Δ G =−7.2 kJ/mol) and driven entirely by a large favorable enthalpy decrease (Δ H =−15.1 kJ/mol) but with an unfavorable entropy decrease (Δ S =−25.6 J/mol/K). The kinetic data were fit to a second‐order equation with the reaction rate constant ( k ) of (2.18±0.10)×10 2 L/(mol·s) under the simulated physiological condition.