Polynucleotide kinase from E. coli infected with the PseT 1 mutant of bacteriophage T4 has been isolated. The PseT 1 enzyme purifies similarly to normal polynucleotide kinase and effectively transfers the γ phosphate of ATP to the 5′ terminal hydroxyl of DNA and RNA. The PseT 1 and normal enzymes require similar magnesium ion concentrations, have the same pH optima and are both inhibited by inorganic phosphate. However, the PseT 1 enzyme is totally lacking the 3′ phosphatase activity associated with normal polynucleotide kinase. The PseT 1 enzyme is a useful tool for the preparation of oligonucleotides with 3′ and 5′ terminal phosphates for use as susbstrates for RNA ligase.
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