BIOL 115 |
| Deoxynucleoside kinases (dNKs) catalyze the phosphorylation of deoxynucleosides to their corresponding monophosphates. The reaction is part of an organism's deoxynucleoside salvage pathway. Besides recycling natural nucleosides, dNKs also play a critical role in the phosphorylation of nucleoside analogues that are prodrugs for treating viral infections and cancer. In humans, four dNKs are responsible for the phosphorylation of deoxynucleosides while insects accomplish the same reaction with a single, broad-specificity enzyme. As their protein structures are superimposable, we have speculated that human dNKs could be engineered to show the same universal substrate specificity as insect dNKs. We engineered human deoxycytidine kinase (hdCK) which phosphorylates dC, dG, and dA but not thymidine, by directed evolution methods and identified variants that turn over all four natural deoxynucleosides. Besides identifying a universal human dNK, our results indicate that two key residues in hdCK's active site control the nucleobase specificity, allowing us to not just broaden but also change the enzyme's nucleobase specificity. Kinetic data on the enzyme variants will be presented. |
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Chemistry and Metabolism
4:30 PM-6:30 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Division of Biological Chemistry |