Studies on the purification and properties of a 6.8-S DNA polymerase activity found in calf-thymus DNA polymerase-alpha fraction.
The heterogeneity of calf thymus DNA polymerase-alpha has been further investigated. In particular, an enzyme (enzyme D) which exhibits higher activity on poly(dA) . (dT)10 (A:T = 20:1) compared with that on activated DNA, has been further purified and its properties compared with two other activities of the DNA polymerase-alpha fraction (enzymes A1 and C) which do not show a preference for poly(dA) . (dT)10 over activated DNA. As with A1 and C, enzyme D was shown to have many of the characteristic properties of DNA polymerase-alpha in that it is an acidic protein as judged by its binding to DEAE-cellulose, has a molecular weight of about 140000, does not use a poly (A) . (dT)10 template-initiator complex and is inhibited by N-ethylmaleimide. It exhibits anomalous gel filtration behaviour on Sepharose 6B and it binds relatively weakly to DNA-cellulose compared with DNA polymerase-beta. The extreme sensitivity of enzyme D to inhibtion by N-ethylmaleimide distinguishes it from A1 and C, as does its elution position from a DEAE-cellulose column. On the other hand enzymes C and D are readily inactivated by heating at 45 degrees C unlike enzyme A1. The possible interrelationships of the multiple activities of calf thymus DNA polymerase-alpha are discussed.
D000818:Animals; D002417:Cattle; D004257:DNA Polymerase II / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000302:isolation & purification / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008099:Liver / Q000201:enzymology; D008970:Molecular Weight; D011067:Poly dA-dT / Q000378:metabolism; D051381:Rats; D013698:Templates, Genetic; D013950:Thymus Gland / Q000201:enzymology*
D011067:Poly dA-dT; D004257:DNA Polymerase II; D004259:DNA-Directed DNA Polymerase; D005033:Ethylmaleimide