Akademik

The radical formed by loss of the hemiacetal OH group from either of the two cyclic forms of ribose (yielding ribofuranosyl and ribopyranosyl compounds), by combination with an H of an –NH– or a –CH– group; the natural nucleosides are r. compounds, not ribosides, as the bond between ribose and aglycon is C–N or C–C, not –C–O–X–.