400657 RU relative units 74 400857 rU ribonucleotides 3 400858 rU ribonucleotide 2 400861 rU radical of uridine 1 400862 rU radicalized uracil 1 400860 rU radicals, and uridine 1 400859 rU ribonucleotide uracil 1 400855 rU ribose uridine 1 400856 rU ribouridine 1