Purification and properties of a low molecular weight DNA polymerase from Neurospora crassa

Abstract

A third DNA polymerase ‘C’ with low molecular weight was isolated and purified 3700-fold from ground hyphae of Neurospora crassa WT 74 A, which shows similarities to β- and γ-polymerases from higher eukaryotes: preference for poly(rA)(dT) as a template/primer, inhibition by p-chloromercuribenzoate, resistance against N-ethylmaleimide up to 10 mmol/l, and molecular weight of about 40 000. This polymerase elutes as a distinct peak from DEAE-cellulose at 0.60 mol/l KCl and has an optimum for K + at 2–20 mmol/l, for Mn 2+ at 0.8 mmol/l, for Mg 2+ at 4.0 mmol/l, the pH optimum is 8.0. Its K m is 1.5 μmol/l using dTTP as substrate. The enzyme activity described here is free of endonuclease but contains detectable amounts of exonuclease.