Taq polymerase - what exonuclease activities?

Jim Owens jow at helix.nih.gov
Fri Feb 18 12:22:39 EST 1994

In article <CLAF5n.Is6 at massey.ac.nz> P. Hirst, PHirst at massey.ac.nz writes:
>I'm trying find out exactly what exonuclease activities Taq polymerase
>has, and which polymerase it is/ or which it's derived from.  The
>literature I've found so far is far from precise in its description, so
>any information anyone has would be greatly appreciated.

According to David Gelfand in Chapter 2 of PCR Technologies: Principles
and Applications for DNA Amplification, Henry A. Erlich (ed), Stockton
Press, 1989:

"Purified 94 kDa Taq DNA polymerase does not contain an inherent 3'-5'
exonuclease activity...  It is not known if T. aquaticuys contain a
separate 3'-5' exonuclease activity which may be associated with the
polymerase in vivo....  Taq DNA polymerase has a DNA synthesis-dependent,
strand replacement, 5'-3' exonuclease activity.  (more details omitted)" 

Hope this helps,

Jim Owens

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