ABSTRACT
The deoxyribonucleic acid (DNA) polymerases have been most extensively studied because of their clear involvement in DNA synthesis. The structural unit of eukaryotic chromosomes is a complex of DNA with an equal weight of histones. Since the first description of DNA polymerase activity in vitro in the late 1950s, a tremendous number of investigations have been done to elucidate the properties and mechanism of action of the enzymes. Intracellular DNA synthesis is regulated by distinct multienzyme systems controlling initiation, propagation, and termination. DNA polymerase has been isolated and purified from a number of animal cells as well as from lower eukaryotes. Many enzymes and proteins that are involved in normal and repair replication of DNA in eukaryotic cells continue to be identified, isolated, and characterized. Chromosomal DNA synthesis in the nucleus of eukaryotic cell proceeds in a regulated transitory pattern. DNA binding proteins have also been isolated from E. coli, bacteriophage-infected E. coli, and mammalian cells.
