Interactions of 6-aminopurine (adenine) in water and aqueous urea solutions

Abstract

Density (ρ), ultrasonic velocity (U), viscosity (η), and absorbance (A) of adenine in water, 1 M, 3 M, and 6 M aqueous urea solutions have been measured in the presence (and absence) of different concentrations of salts, i.e., NaCl, KCl, and CaCl2. From these measured values, the apparent molar volume (ϕv), experimental slope (Sv), apparent molar compressibility (ϕK), viscosity coefficients A and B of Jones–Dole equation, specific acoustic impedance (Z), hydration number (Sn), internal pressure (Pi), molar absorptivity (ε), hypochromicity (h), and oscillator strength (f) have been calculated at 298.15 K. The increasing and (or) decreasing trends of all these parameters indicate a strong interaction of urea in moderate concentration (1 M and 3 M) with adenine especially at the hydrophilic/polar and ionic sites, particularly by hydrogen bonding. However, the interaction at hydrophobic sites are relatively weaker. Higher concentrations of urea (6 M) have more denaturation effect. The π–π interactions (stacking) in adenine are more prominent in concentrated solutions and are also strengthened by the presence of cations up to an optimum concentration of salts (cut-off point). The self-association of urea and adenine is more significant in concentrated aqueous solutions and becomes negligible on dilution.Key words: interaction, adenine, urea, density, viscosity, and ultrasonic velocity.

Sound Velocities and Micellar Behaviour Studies of Dodecyltrimethylammonium Bromide in Aqueous Solutions at 295.15, 302.15 and 309.15 K

“…Density, ρ, and Speed of sound, u, measurements are combined to calculate isentropic compressibility, K s, using the Laplace equation (Pandey et al, 2000)…”

Acoustical Studies of Some Schiff Bases in 1,4‐Dioxane and Dimethylformamide at 318.15 K

“…The literature survey shows that various workers studied acoustical parameters mostly for liquids, [1][2][3] liquid mixtures, [3][4][5][6] solutions of salts, 7,8 polymers, 9,10 biological molecules [11][12][13] etc. In our laboratory, we have studied acoustical properties of some Schiff bases in different solvents.…”

Effect of Na+, K+ and Ca2+ Ions on Physico‐chemical Properties of Thymine, Cytosine, Thymidine and Cytidine in Aqueous Urea Solution

“…Recently interactions of adenine in water and aqueous urea solutions of different concentrations have been studied in the presence or absence of metal ions. 6 Thermochemical and sonochemical studies of adenosine in DMSO in the presence of Na ＋ or Ca 2＋ have been also carried out. 7 A wide variety of techniques have been applied [8][9][10] singly or jointly to understand the interaction behaviour of nucleic acids with metal ions.…”