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Enzyme Kinetics

The enzyme succinoxidase adds oxygen to succinate to give fumarate. The reaction follows Michaelis-Menton kinetics. The following rate data were determined for a solution in which the enzyme concentration is 10.0 uM:

[S](mM) ----------------- 0.33 10.00
vo (uM s-1) at 20 C ----- 0.50 1.17
vo (uM s-1) at 40 C ----- 2.41 5.65

(a) Determine Vmax and Km for the reaction at 20 C and 40 C.

For this question, I know that the Michaelis-Menton equation is:

vo = Vmax/1 + Km/[S]
- the equation then becomes:
vo = k2*[E]/ 1 + Km/[S]

We know what vo is for, [E],and [S], but k2 is not known. I'm not sure how to proceed with this question unless k2 is known.

(b) Compute the activation energy of this reaction (succinate + O2 --> fumarate).

For this question, would the equation K2/k1 = -Ea/R[1/T2 - 1/T1] be used. T2 and T1 is known, R is a constant (8.314) but how is k2 and k2 calculated. This part I do not understand.

(c) Will the activation energy be higher or lower in the absence of succinoxidase? Why?

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Solution Preview

Another form of the Michaelis-Menten equation is: vo/Vmax = [S]/(Km + [S])

In the (a) part, since you know vo at two different substrate concentrations, you can substitute these into the MM equation. Then you ...

Solution Summary

This solution includes a rationale on how to answer all three parts of this question regarding enzyme kinetics. Based on what is known for parts a-c, guidance is given in terms of what equations to utilize to calculate certain values and how to interpret the question. All of this is done in about 250 words.