Partial purification and characterization of DNA polymerases from the cauliflower inflorescence.

Abstract

Two distinct DNA polymerases, designated A and B, have been partially purified from rapidly growing apical tissues of the cauliflower inflorescence (Brassica oleracea, var. botrytis). They were readily separable from each other, because enzyme A was adsorbable on an anion-exchanger, but enzyme B was not. The effects of divalent rations and ionic strength on both enzyme activities were very different. Enzyme A utilized activated DNA well at low concentration of MgCl2 or at low ionic strength, but heat-denatured DNA was utilized more effectively than was activated DNA at high concentration of MgCl2. Enzyme B also utilized much more heat-denatured DNA and poly (rA)•(dT)10 at high ionic strength. Gel chromatography with Sephadex G-200 revealed that enzyme A has a higher molecular weight (approx. 100, 000) than enzyme B (approx. 75, 000). It has been also described that some points of properties in enzyme A and B resemble to those of the two DNA polymerase -α and -β from mammalian cells, respectively. The existence of the third enzyme, designated C, in the fraction with enzyme A was suggested with an assay system using poly (rA)•(dT)10 as the template.