Biochemists consider the citric acid cycle to be the central reaction sequence in metabolism. One of the key steps is an oxidation catalyzed by the enzyme isocitrate dehydrogenase and the oxidizing agent NAD+. Under certain conditions, the reaction in yeast obeys llth-order kinetics:

Rate = k[enzyme][isocitrate]4[AMP]2[NAD+]m[Mg2+]2,

What is the order with respect to NAD+?

The rate of the reaction is directly proportional to the active concentration of the reactant which each are raised to the experimentally determined coefficients which are known as orders. The rate is determined by the slowest step in the reaction mechanics.

Order of in the mass action law is the coefficient which is raised to the active concentration of the reactants. It is experimentally determined and can be zero, positive negative or fractional.

The order of the whole reaction is the sum of the order of each reactant which is raised to its power in the rate law.

The given rate law is:-

[tex]Rate = k[enzyme][isocitrate]^4[AMP]^2[NAD^+]^m[Mg^{2+}]^2[/tex]

The overall rate = 11

Rate of overall reaction = 1 + 4 + 2 + m + 2 = 11

9 + m = 11

m = 2

Order w.r.t. [tex]NAD^+[/tex] = 2