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Purification and characterization of the vaccinia virus deoxyuridine triphosphatase expressed in Escherichia coli
- Source :
- The Journal of biological chemistry. 271(38)
- Publication Year :
- 1996
-
Abstract
- The deoxyuridine triphosphatase gene of vaccinia virus, encoded by the open reading frame F2L, was cloned into Escherichia coli and expressed under the control of a bacteriophage T7 promoter. After induction of T7 RNA polymerase by isopropyl beta-D-thiogalactopyranoside, a 16.5-kDa peptide accumulated to high levels. This 16.5-kDa protein was purified to homogeneity and characterized. Gel filtration of the purified protein revealed a trimeric native structure. Biochemical analysis revealed the enzyme to be a metalloenzyme; enzymatic activity is inhibited by EDTA. This inhibition was reversed by the addition of Mg2+, Mn2+, or Zn2+. While the enzyme activity was highly specific for dUTP with an apparent Km of 0.94 microM, inhibition studies show that 8-azido-ATP acted as a competitive inhibitor of dUTP with a Ki of approximately 173 microM. Also, protection studies demonstrated that nucleotide competitors inhibit photoincorporation of the photoaffinity analogues [gamma-32P]5-azido-dUTP and [gamma-32P]8-azido-ATP. This suggests that while catalytic activity is limited to dUTP, other nucleotides can bind the active site.
Details
- ISSN :
- 00219258
- Volume :
- 271
- Issue :
- 38
- Database :
- OpenAIRE
- Journal :
- The Journal of biological chemistry
- Accession number :
- edsair.pmid..........7da573b5a529ae57206be06536f89475