Hi I'm working with an enzyme which appears to have some degree of product inhibition. It has a very fast initial rate and a huge dip in rate followed by a steady rate. I suspect this may be product inhibition but the enzyme's products are not easily isolated to test that. Can I determine the extent of this by a regular enzyme assay?
Best wishes
Harry
It sounds more like burst kinetics than product inhibition. What were the enzyme concentration and resulting product concentration formed during the reaction?
Many variables may have taken place during your experiments; first your enzyme concentration or substrate concentration may be limited during assay, put both in access; second how much time you utilise for your assay, if it is long then it is unavoidable, try to keep minumum; third there are many successful strategy to overcome product inhibition depending on your enzyme.
Dear Harry,
could you please name the enzyme you work with? Because I work with pyruvate and 2-oxoglutarate dehydrogenase complexes which possess the similar behaviour. And I agree with Dr. Shapiro that it's initial burst, not product inhibition, since you observe stationary phase after it.
The most important factors affecting the rate of enzymatic reactions are: enzyme concentration, concentration of the ligands (substrates, products, inhibitors and activators), pH, ionic strength and temperature. You should take into account a number of parameters such as the initial velocity (Vo) t = 0 since the reaction will not reverse and there is no product formation at that stage of the reaction. The Vo will depend only on the concentrations of the reactants. Another parameter to take into account would be Km is characteristic of an enzyme against a particular substrate and in the conditions of pH and temperature of the experiment. That is, to know the kinetics, Michaelis-Mentten (Km = Ks) or Briggs-Haldane, etc.
Good luck regards
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