Imidazole Rescue of a Cytosine Mutation in a Self-Cleaving Ribozyme
- 1 October 1999
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 286 (5437) , 123-126
- https://doi.org/10.1126/science.286.5437.123
Abstract
Ribozymes use a number of the same catalytic strategies as protein enzymes. However, general base catalysis by a ribozyme has not been demonstrated. In the hepatitis delta virus antigenomic ribozyme, imidazole buffer rescued activity of a mutant with a cytosine-76 (C76) to uracil substitution. In addition, a C76 to adenine substitution reduced the apparent pKa(whereKais the acid constant) of the self-cleavage reaction by an amount consistent with differences in the pKavalues of these two side chains. These results suggest that, in the wild-type ribozyme, C76 acts as a general base. This finding has implications for potential catalytic functions of conserved cytosines and adenines in other ribozymes and in ribonuclear proteins with enzymatic activity.Keywords
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