Inhibitor studies of phage T4 wild-type and mutant DNA polymerases. II. Differential inhibition by pyridoxal 5'-phosphate.

The sensitivities to pyridoxal 5'-phosphate of phage T4 wild-type and two ts mutant DNA polymerases, L98 (mutator) and CB 121 (antimutator), were studied. The wild-type and the mutator enzyme we inhibited to an equal extent, while the antimutator enzyme was six times more sensitive. The mode of inhibition was competitive with the deoxynucleoside triphosphate substrates. The CB121 DNA polymerase had a three times lower affinity to its substrates but a twofold affinity to pyridoxal 5'-phosphate. The L98 enzyme had lower affinities to both the substrates and the inhibitor.