ABSTRACT
DNA-binding proteins unwind DNA helix, while others bind to the single-stranded DNA and even stimulate homologous DNA polymerase activities. DNA polymerase α has been isolated and purified from a number of animal cells as well as from lower eukaryotes. 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 these enzymes. The DNA polymerase are three different types: DNA polymerases α, DNA polymerases β, and DNA polymerases γ. At least three different types of DNA polymerization can be classified: replicative nuclear DNA synthesis, repair DNA synthesis, mitochondrial and adenovirus DNA synthesis. Infidelity of DNA synthesis by mutagenized or altered DNA polymerases has been proposed as a mechanism for the accumulation of somatic mutations and subsequent alteration in cellular control. DNA ligases are DNA-joining enzymes that join single-strand breaks in double-stranded DNA by catalyzing the formation of phosphodiester bonds.
