Open AccessEvidence that DNA Polymerase‐a of Calf Thymus Contains a Subunit of Molecular Weight 155000
Author(s) -
HOLMES Andrew M.,
HESSLEWOOD Ian P.,
JOHNSTON Irving R.
Publication year - 1976
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1976.tb10152.x
Subject(s) - polyacrylamide gel electrophoresis , enzyme , protein subunit , polymerase , gel electrophoresis , microbiology and biotechnology , urea , dna polymerase , polyacrylamide , electrophoresis , dna , biochemistry , chemistry , biology , gene
Small samples of the 8‐S species of enzymes (A 1 and A 2 ) occurring in the DNA polymerase‐a fraction of calf thymus, have been extensively purified using non‐denaturing (normal) polyacrylamide gel electrophoresis. When peak fractions of activity on normal gels were subjected to dodecylsulphate‐polyacrylamide gel electrophoresis, a polypeptide at 155000 correlated with polymerase activity. Samples of the 7.3‐S (C) enzyme prepared from A 2 by treatment with 2.4 M urea or isolated directly without exposure to urea, also showed the presence of a 155000‐ M r polypeptide. It is concluded that the 7.3‐S (C) enzyme, of previously estimated molecular weight 155000–170000, is a single polypeptide and that the 8‐S enzymes A 1 and A 2 contain an additional subunit of 50000–70000 molecular weight.