The kinetics Of the ATCase reaction were examined using incr

The kinetics Of the ATCase reaction were examined using increasing concentrations of aspartate, in the pre Hence and absence of (TP and ATP as shown in Figure 16.2. a. What information can you obtain by looking at the shapes of the curves in this figure? b. What kinetic parameter(s) change in the presence of CTP? What parameter(s) do not change? What is the significance of these observations? c. Answer question 2b for ATP.

Solution

Anwer:

Information from the shape of the curve:

Control: A plot of substrate (aspartate) concentration versus velocity is represented showing a sigmoidal curve. The binding of aspartate to one active site convert the entire enzyme into the R state, which increases the activity of other active sites (cooperativity). So it shows a sigmoidal curve.

With CTP: (T state curve) It allosterically inhibits the ATCase enzyme, making substrate binding difficult, thus stopping it from reaching the R state and thus stabilising Tensed (T) state. Thus, the curve is shifted to the right.

With ATP: It allosterically activate the enzyme thus stabilizing the Relaxed (R) state, shifting the curve to left.

b .

Kinetic Parameters that change in the presence of CTP: The Km or concentration of substrate for half-saturation, for aspartate is increased for that molecule.

Kinetic Parameters that is unchanged in the presence of CTP: Vmax (maximum rate of reaction) is unchanged.

C.

Kinetic Parameters that change in the presence of ATP: The Km or concentration of substrate for half-saturation, for aspartate is decreased for that molecule.

Kinetic Parameters that is unchanged in the presence of CTP: Vmax is unchanged.