BIOL 90 |
| Thymidine kinases (TKs) play a vital role in nucleotide biosynthesis and in the activation of nucleoside analogue prodrugs. Previous studies of TKs have been limited to enzymes from mesophilic organisms, prompting our interest in novel and potentially improved kinases from extremophiles. We have now isolated and characterized the first TK from a hyperthermophilic organism, the eubacterium Thermotoga maritima (TmTK) and investigated its biochemical and biophysical properties. As expected, TmTK is extraordinarily thermostable and, consistent with other kinases in its family, shows narrow substrate specificity for natural deoxynucleosides with thymine or uracil nucleobases. In contrast, when tested with nucleoside analogues at 37?C, TmTK shows up to 100-fold increased activity for nucleoside analogues as compared to mesophilic kinases. Supported by spectrophotometric data, we are hypothesizing that protein rigidity and conformational changes contribute to the enhanced catalytic activity. Results from protein engineering efforts to further enhance TmTK's substrate specificity 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 |