Deoxyribonucleic Acid Polymerase from Wheat Embryos

A soluble DNA-dependent DNA polymerase was extracted from wheat embryos. In vitro, the incorporation of radioactive thymidine triphosphate into acid-insoluble material is dependent upon the presence of the enzyme, all four deoxyribonucleotide triphosphates, Mg(2+), and a DNA template. Incorporation occurs on native, alkali-denatured, and strictly double-stranded DNA. The in vitro synthesized product is a polydeoxynucleotide with a chain length shorter than the template; it has the same buoyant density as wheat embryo DNA when this DNA is used as template; and it forms a double-stranded complex with the DNA template. These data suggest that the in vitro DNA synthesis catalyzed by proteins extracted from wheat embryos occurs in a semiconservative way.