Park Seung Kyu (skpark at POST.MIYAZAKI-MED.AC.JP) wrote:
: The unit of a enzyme is variable according to the assaying conditions. I
: want to use the enzyme in the fixed condition which is not standard or
: optimum for the enzyme, so, I may re-check the unit. For that, which
: experimental procedures shoud I follow? I basically learned the enzyme
: kinetics including Michaelis-Menten equation. But, experimentally, the
: Km or Vmax which can be got by change the concentration of substrate is
: varied if I change the mass of the enzyme added. Kind answers would be
: appreciated.
Dear Seung Kyu,
You will have to find the procedure by which the unit of the
particular enzyme is defined. Usually, this is the activity which
converts a specified amount of a particular substrate to product in
a specified time under standard conditions. Methods in Enzymology has
these procedures listed for many enzymes, but you may have to go to the
literature. Once you have the appropriate procedure for your enzyme,
you can run it (several times) with aliquots of your preparation to
get units/mg and a standard deviation--you can also determine if the
activity is linear with concentration. Subsequently, you can do the
same thing under your non-standard conditions to get a conversion
factor between your assay and that for standard conditions. Good luck.
Yours,
Bill Tivol
