Initially, it was believed that the 75th nucleotide in the ribozyme, a cytosine known as C75, was able to act as a general base with the N3 of C75 abstracting a proton from the 2′-hydroxyl of the U(-1) nucleotide to facilitate nucleophilic attack on the phosphodiester bond.
Initially, it was believed that the 75th nucleotide in the ribozyme, a cytosine known as C75, could serve as a general base. This involved the N3 of C75 removing a proton from the 2′-hydroxyl of the U(-1) nucleotide to facilitate an attack on the phosphodiester bond.