in the absence of any such hydrogen bonding , the imidazole nucleosides expectedly exhibit nearly 'free ' rotation around the glycosyl bond for the commonly found c ( 3 ' ) endo and c ( 2 ' ) endo sugar ring conformations , thus increasing the probability of anti in equilibrium high-anti in equilibrium syn conformational interconversions as compared to common purine and pyrimidine nucleosides .
C0028621
nucleosides
C0034287
pyrimidine nucleosides