Open AccessStudies on the Purification and Properties of a 6.8‐S DNA Polymerase Activity Found in Calf‐Thymus DNA Polymerase‐α Fraction
Author(s) -
HESSLEWOOD Ian P.,
HOLMES Andrew M.,
WAKELING William F.,
JOHNSTON Irving R.
Publication year - 1978
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1978.tb12148.x
Subject(s) - dna polymerase , polymerase , dna , dna clamp , enzyme , microbiology and biotechnology , biochemistry , dna polymerase i , dna polymerase ii , biology , polymerase chain reaction , chemistry , gene , reverse transcriptase
The heterogeneity of calf thymus DNA polymerase‐α 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‐α fraction (enzymes A 1 and C) which do not show a preference for poly(dA) · (dT) 10 over activated DNA. As with A 1 and C, enzyme D was shown to have many of the characteristic properties of DNA polymerase‐α 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‐β. The extreme sensitivity of enzyme D to inhibition by N ‐ethylmaleimide distinguishes it from A 1 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 °C unlike enzyme A 1 . The possible interrelationships of the multiple activities of calf thymus DNA polymerase‐α are discussed.