Why use K+ and NH4+ in Taq buffer?

WS via methods%40net.bio.net (by novalidaddress from nurfuerspam.de)
Wed Apr 2 18:02:11 EST 2008


Dear SiLin,

total ionic strength doesn't differ so much. It's most likely due to
patent and other legal issues and/or due to the composition of the Taq
storage buffer that the PCR buffers differ in composition. Seems that
in real life these differences do not affect Taq  much but of course
require you to optimise a PCR for each polymerase/buffer composition.
(another way nasty companies annoy scientists to stay with their
products).

Furthermore, (that's my personal explanation for the ammonium salts)
some Taqs are hot start and reversibly blocked (by imino group
formation with eg lysines) with formaldehyde (btw, thats how some
people make their homebrew hot start Taq, too). This formaldehyde -
once liberated by heat- can be caught by the excess of ammonium ions
and thus won't afftect the Taq anymore.

Best regards,

Wo


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