nucleoside conformation syn nucleoside conformation A syn nucleoside conformation is a nucleoside conformation characterized by the nucleobase being oriented towards the ribose due to rotation about the glycosidic torsion angle χ. From χ = 0°, where the plane of the base is aligned with the O4’-C1’ bond in a direction towards the O4’ atom, the syn conformation covers the remaining rotations of ±90°: χ = [-90°, 90°]. PERSON: Michel Dumontier anti nucleoside conformation