Karl Voss karl at
Sun Jul 7 11:28:41 EST 1996

Dr. Duncan Clark (duncan at wrote:

> ThermoSequenase is a mutation of a thermus DNA polymerase, possibly taq
> but they haven't said. It is not a thermostable version of the
> bacteriophage T7 derived Sequenase. The mutation allows ThermoSequenase
> to incorporate ddNTP's more efficiently than dNTP's (over 1000 increased
> usage of ddNTP's compared to Taq). This gives more even peaks. The
> enzyme is very similar to the new AmpliTaqFS. You cannot substitute
> ordinary taq polymerase for ThermoSequenase. If you do you won't get any
> sequence because the termination mixes are totally different for each
> polymerase.

Thermosequenase is a single aminoacid mutation of taq polymerase, designed 
by Tabor and Richardson.  I believe that it is a tyrosine to phenylalanine 
change or vice versa (I can find out for sure if anyone is interested).  
The thermosequenase kit also includes a thermostable pyrophosphatase that 
is also important for maintaining even peak heights. 

We use the thermosequenase kit for all our sequencing.  It is the best
kit that we have tried to this date.  I have even left the kit sitting at 
room temperature overnight and it didn't mind a bit.  

Good luck


Karl Voss
Department of Chemistry
University of Alberta
Edmonton, Alberta, Canada
T6G 2G2

karl at
phone 403-492-0222
fax   403-492-8231

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