Modelling of vitamin A binding to tRNA

Location of multiple binding sites for testo and testo-Pt(II) with tRNA

We report the binding of testo and testo-Pt(II) complexes (testosterone derivatives) with tRNA in aqueous solution at physiological pH. Thermodynamic parameter ΔH₀ -8 to -3 (kJ mol^-1), ΔS₀ 35 to 18 (J mol^-1K^-1) and ΔG₀ -14 to -13 (kJ mol^-1) and other spectroscopic results showed drug-tRNA binding occurs via ionic contacts with testo-Pt(II) forming more stable tRNA complexes in comparison to testo: K_testo-Pt(II)-tRNA= 3.2 (± 0.9) × 10⁵ M^-1 > K_testo-tRNA= 2.1 (± 0.7) × 10⁵ M^-1. Molecular modeling showed multiple binding sites for testo and testo-Pt(II) on tRNA molecule. Some of the useful molecular descriptors are calculated. Major structural changes were observed for biopolymers upon drug complexation, while tRNA remains in the A-family structures.

Locating the binding sites of antioxidants resveratrol, genistein and curcumin with tRNA

We located the binding sites of antioxidants resveratrol, genistein and curcumin on tRNA in aqueous solution at physiological conditions using constant tRNA concentration and various polyphenol contents. FTIR, UV-visible, CD spectroscopic methods and molecular modeling were used to determine polyphenol binding sites, the binding constant and the effects of polyphenol complexation on tRNA conformation and particle formation. Structural analysis showed that polyphenols bind tRNA via G-C and A-U base pairs through hydrophilic, hydrophobic and H-bonding contacts with overall binding constants of K(res-tRNA)=8.95(±0.80)×10(3) M(-1), K(gen-tRNA)=3.07(±0.5)×10(3) M(-1) and K(cur-tRNA)=1.55(±0.3)×10(4) M(-1). Molecular modeling showed the participation of several nucleobases in polyphenol-tRNA adduct formation with free binding energy of -4.43 for resveratrol, -4.26 kcal/mol for genistein and -4.84 kcal/mol for curcumin, indicating that the interaction process is spontaneous at room temperature. While tRNA remains in A-family structure, major biopolymer aggregation and particle formation occurred at high polyphenol contents.