Abstract
Abstract About 80 % of the DNA polymerase activity, extractable with buffer [0.05 M Tris-HC1 (pH 8.0), 0.001 M MgCl2, 0.01 M β-mercaptoethanol, 0.25 M sucrose] from normal and bacteria-free crown gall tumor tissue cultures of tobacco, was found in the 37 000 × g supernatant. This DNA polymerase, which utilized as a template denatured calf thymus DNA more efficiently than native DNA, was 10 times higher in tumor than in normal tissue. Only limited polymerization (10 % for normal and 2 % for tumor, compared to the complete mixture) was found when dATP, dCTP and dGTP were omitted. Chromatin was a poor template for endogenous DNA polymerase but a relatively better primer for endogenous terminal deoxynucleotidyltransferase activity. DNA polymerase activity of the chromatin as assayed in the presence of denatured calf thymus DNA was 30-fold higher in tumor than in normal tissue. On the other hand, the terminal deoxynucleotidyltransferase activity (assayed in the presence of denatured DNA) of normal tissue chromatin was twice that of tumor tissue.
Published Version
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