JBC, Vol. 250, Issue 22, 8657-8663, Nov, 1975
A DNA polymerase from embryos of Drosophila melanogaster. Purification and properties
J. D. Karkas, L. Margulies and E. Chargaff
The more than 2,300-fold purification of a DNA polymerase from the embryos
of Drosophila melanogaster is described. The enzyme, which forms a single
band on gel electrophoresis, has a molecular weight of about 87,000 and a
pH optimum of 8.5. A divalent metal is required for activity, Mg2+ being
preferred with activated DNA, Mn2+ with homopolymer template-primers. The
enzyme is inactivated completely by mercurials; polyamines are also
inhibitory with certain templates. The most efficient template-primer is
activated DNA, but homopolymers such as poly(dA)-oligo(dT),
poly(A)-oligo(dT), and poly(A)-oligo(U) are also utilized with high
efficiency. The purified enzyme preparations appear to be devoid of
nuclease activity when assayed directly with suitable substrates. In
addition, neither primer nor product is degraded after prolonged incubation
with the enzyme. In accordance with previous observations on other DNA
polymerases, the Drosophila enzyme can replicate single-stranded DNA only
under conditions of simultaneous transcription by RNA polymerase.
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