Conformational characteristics of 4-acetylcytidine found in tRNA.

The conformational characteristics of a modified nucleoside 4-acetylcytidine (ac4C) was analyzed by proton nuclear magnetic resonance spectroscopy. This nucleoside was found to take the C3'-endo form predominantly. The enthalpy difference between the C2'-endo form and the C3'-endo form of the ribose moiety of ac4C was determined and 4-acetylation was found to stabilize the C3'-endo form further by 0.83 kcal.mol-1. This conformational characteristics of ac4C is probably important for the correct codon recognition and the stability of the tertiary structure of tRNA molecule.