Identification and tryptic cleavage of the catalytic core of HeLa and calf thymus DNA polymerase epsilon.

摘要: Abstract DNA polymerase epsilon, formerly known as a proliferating cell nuclear antigen-independent form of delta, has been shown elsewhere to be catalytically and structurally distinct from delta. The catalytic activity HeLa an enzyme consisting greater than 200- 55-kDa polypeptides, was assigned the larger polypeptide by trap reaction. This cleaved incubation with trypsin into two fragments molecular masses 122 136 kDa, former which relatively resistant further proteolysis possessed activity. cleavage increased exonuclease activities some 2-3-fold. epsilon also purified in smaller 140-kDa calf thymus. digestion this generated 122-kDa polypeptide. These results suggest that core is 258-kDa composed segments linked protease-sensitive area. One harbors both 3'----5' activities. In spite different structures, properties enzyme, its trypsin-digested form, thymus remained essentially same.