Calf thymus polymerase.

The term polymerase has been applied to the deoxyribonucleoside triphosphate-polymerizing enzyme isolated from Escherichia coli (1). Enzymes with similar activity have been purified from regenerating rat liver (2) and calf thymus gland (3). An ample and varied supply of such polymerases is desirable for studies on the mechanism of deoxyribonucleic acid synthesis. The present work describes a partial purification of the calf thymus polymerase and demonstrates the gross properties of the synthetic reaction. Certain useful properties of this enzyme preparation are currently being exploited for studies on the nature of primer DNA (4).