Polynucleotide kinase (bacteriophage-T4-infected Escherichia coli B) catalyses the transfer of the [gamma-16O,17O,18O]phosphoryl group from 5′[gamma(S)-16O,17O,18O]ATP to 3′-AMP with inversion of configuration at the phosphorus atom. The simplest interpretation of this observation is that the [gamma-16O,17O,18O]phosphoryl group is transferred directly from ATP to the co-substrate by an ‘in-line’ mechanism.
