In 2002,Major, Dan T.; Laxer, Avital; Fischer, Bilha published 《Protonation Studies of Modified Adenine and Adenine Nucleotides by Theoretical Calculations and 15N NMR》.Journal of Organic Chemistry published the findings.Recommanded Product: 16681-56-4 The information in the text is summarized as follows:
The acid/base character of nucleobases affects phenomena such as self-association, interaction with metal ions, mol. recognition by proteins, and nucleic acid base-pairing. Therefore, the investigation of proton-transfer equilibrium of natural and synthetic nucleos(t)ides is of great importance to obtain a deeper understanding of these phenomena. For this purpose, a set of ATP prototypes was investigated using 15N NMR spectroscopy, and the corresponding adenine bases were investigated by theor. calculations 15N NMR measurements provided not only acidity constants but also information on the protonation site(s) on the adenine ring and regarding the ratio of the singly protonated species in equilibrium Substituents of different nature and position on the adenine ring did not change the preferred protonation site, which remained N1. However, for 2-thioether-ATP derivatives a mixed population of N1 and N7 singly protonated species was observed Reduction of basicity of 0.4-1 pKa units relative to ATP was also observed for all evaluated ATP derivatives, except for 2-Cl-ATP, for which Ka was ∼10,000-fold lower. To explain the substitution-dependent variations in the exptl. pKa values of the ATP analogs, gas-phase proton affinities (PA), ΔΔGhyd, and pKa values of the corresponding adenine bases were calculated using quantum mech. methods. The computed PA and ΔΔGhyd values successfully explained the exptl. pKa values. A computational procedure for the prediction of accurate pKa values was developed using d. functional theory and polarizable continuum model calculations In this procedure, we developed a set of parameters for the polarizable continuum model that was fitted to reproduce exptl. pKa values of nitrogen heterocycles. This method is proposed for the prediction of pKa values and protonation site(s) of purine analogs that have not been synthesized or analyzed. In the experimental materials used by the author, we found 2-Bromo-1H-imidazole(cas: 16681-56-4Recommanded Product: 16681-56-4)
2-Bromo-1H-imidazole(cas: 16681-56-4) is a member of imidazole. Its exclusive structural characteristics with enviable electron-rich features are favorable for imidazole-based fused heterocycles to bind efficiently with an array of enzymes and receptors in biological systems through various weak interactions like hydrogen bonds, ion-dipole, cation-π, π-π stacking, coordination, Van der Waals forces, hydrophobic effects, etc., and therefore they demonstrate widespread bioactivities. Recommanded Product: 16681-56-4
Referemce:
Imidazole – Wikipedia,
Imidazole | C3H4N2 – PubChem