Eliasson, RolfReichard, PeterMulliez, EtienneOllagnier, SandrineFontecave, MarcLiepinsh, EdvardsOtting, Gottfried2026-03-232026-03-230006-291XPubMed:7669047ORCID:/0000-0002-0563-0146/work/209074905https://hdl.handle.net/1885/733807641During the reduction of ribonucleotides with [3H]formate by the class III anaerobic ribonucleotide reductase from Escherichia coli tritium appears in water and not in the product deoxyribonucleotide. In D2O, deuterium replaces the OH-group at carbon-2′ with retention of configuration. In addition we find 1-2 % deuterium in the 3′-position demonstrating a small exchange of this hydrogen with the protons of water during catalysis. Class I and II enzymes catalyze identical reactions. Members of the three classes of reductases apparently use the same chemical mechanism in spite of having completely different protein structures.8en1995-09-0510.1006/bbrc.1995.22520029093215