Studies on the activity of the A particle-associated Dna polymerase.

The DNA polymerase activity in preparations of A particles from mouse myeloma has been further character ized. Most of the radioactive product from reactions containing poly(rA)-(dT)12 18and dTTP-3H was composed of dTMP-3H in the form of nuclease-sensitive macromolecules with an average density of 1.428 g/ml, deter mined in cesium sulfate gradients at neutral pH; the product therefore possessed characteristics of poly(dT). Approxi mately 50% of this product was similar in size to the template, poly(rA), while the remainder was of lower molecular weight. Studies on the kinetics of the poly(rA)-(dT)12 18-dependent incorporation revealed that enzyme activity was optimal at 37°,with an apparent