Conformational flipping of the N(6) substituent in diprotonated N6-(N-glycylcarbonyl)adenines: The role of N(6)H in purine-ring-protonated ureido adenines

✍ Scribed by Kailas Dasharath Sonawane; Uddhavesh Bhaskar Sonavane; Ravindra Tewari

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 193 KB
• Volume: 78
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(2000)78:5<398::aid-qua8>3.0.co;2-t

✦ Synopsis

Conformational transitions of the N(6) substituent, in hypermodified nucleic acid base N 6 -(N-glycylcarbonyl)adenine, gc 6 Ade, on diprotonation of the adenine ring at any two of N(1), N(3), and N(7) sites, are studied using the quantum chemical perturbative configuration interaction with localized orbitals (PCILO) method. The N(6) substituent retains the usual "distal" orientation (α = 0 • ) in (N(1), N(3)) diprotonated gc 6 Ade, but the "proximal" orientation (α = 180 • ) is preferred instead, for (N(3), N(7)) and (N(7), N(1)) diprotonated gc 6 Ade. The proximal orientation may alter the reading frame during translation. Intramolecular N(6)H. . .O(13b) hydrogen bonding is the key common feature, present in the preferred structure, for each of these variously diprotonated gc 6 Ade.