Changes in some enzymes involved in DNA biosynthesis following induction of division in cultured plant cells.

The biosynthetic enzymes DNA polymerase, thymidine kinase (TdR kinase) and thymidine monophosphate kinase (dTMP kinase) show characteristic patterns of activity associated with cell division in synchronously dividing tissue cultures of the Jerusalem artichoke. In each case the first major increase in enzyme activity is coincident with and dependent upon DNA replication. In addition the increased activities of all 3 enzymes are not due to the activation of pre-existing enzyme or to the removal of inhibitors. A theory is advanced to account for the close correlation between DNA synthesis and the major rise in activity of the 3 enzymes.