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Dielectric Relaxation in ATP and AMP aqueous solutions


  Evgeniya Levy[1]  ,  Alexander Puzenko[1]  ,  Andrey Shendrik[1]  ,  Ido Segev[1]  ,  Mark Talary[2]  ,  Andreas Caduff[2]  ,  Yuri Feldman[1]  
 [1] The Hebrew University of Jerusalem, Jerusalem 91904, Israel
[2] 2Solianis Monitoring AG, Leutchenbachstrasse 46, 8050 Zürich, Switzerland

It has been traditional to divide the water present in biological tissues into bound or free depending upon its proximity or otherwise to neighboring macromolecules, membranes or other kinds of interface.

The dielectric dispersion in most of biological systems follows the Cole-Cole (CC) dispersion[1]. This is typical for various aqueous systems[2], including ionic solutions, aqueous solutions of physiologically active non-ionic molecules, such as nucleotides, amino acids and sugars, etc[3]. Phenomenologically, CC law can be represented by a frequency dependent complex dielectric permittivity ε*(ω), given by: ε*(ω)=ε∞+Δε /[1+(iωτ)α], where ω is the cyclic frequency, i is the imaginary unit, ε∞ is the high frequency limit of the complex dielectric permittivity, Δε is the dielectric strength of the relaxation process, τ is a characteristic time scale and the exponent α is referred to as a measure of symmetrical broadening in the dielectric losses relaxation peak (0<α≤1). It has been found experimentally that a is strictly dependent on temperature, structure, composition, pressure and other controllable physical parameters[4].

The main goal of this research is to study the hydration of the Adenosine-5'-triphosphate (ATP) in aqueous solution in comparison with Adenosine monophosphate (AMP) molecule. The dielectric measurements of ATP and AMP solutions as the functions of temperature and concentrations were provided in the broad frequency range (1 MHz ÷ 50 GHz) with the help of Time Domain Dielectric Spectroscopy (TDDS) and Millimetre Vector Network Analyser (MVNA).

The analyses and discussion of the γ-dispersion observed in the ATP and AMP aqueous solutions was terms of CC α(lnτ) dependences. 

References

[[1]] K.S. Cole, R.H. Cole J. Chem. Phys. 9, 341 (1941).

[[2]] Y. Hayashi, N. Shinyashiki, S. Yagihara. J. Non-Cryst. Solids. 305, 328 (2002).

[[3]] K. Fuchs, U. Kaatze. J. Phys. Chem. B. 105, 2036 (2001).

[[4]] Y. Feldman, A. Puzenko, Ya. Ryabov. in S.A. Rice, Y.P. Kalmykov, W.T. Coffey, Eds., Fractals, Diffusion and Relaxation in Disordered Complex Systems, Adv. Chem. Phys. 133 A, 1 (2006).