Question

Part A: You are given a beaker containing a solution of an enzyme that hydrolyzes adenosine triphosphate (ATP) while it generates a lot of heat. You add a substantial amount of the sodium salt of ATP, and you measure the temperature of the beaker, and determine that nothing is happening. The enzyme is not performing the reaction. What is a reasonable chemical to add to the solution to get the enzyme to proceed with the hydrolysis of adenosine triphosphate?
Sulfur oxide,
Iron chloride,
magnesium chloride,
or add more sodium ATP.
Part B: You are investigating the reduction of oxygen that is performed by cytochrome c oxidase. As you start the reaction in a slightly acidic aqueous buffer with 2 mM Cu2SO4 and bubbling oxygen into the buffer. As the reaction proceeds, the solution slowly turns blue, what is happening?
a) Ozone is formed. This causes the solution to turn blue.
b) The copper is getting oxidized from Cu+ to Cu2+ and turns blue.
c) The cytochrome c oxidase protein is decomposing down to a blue product.
d) The pH of the solution is changing. Cu2SO4 is a pH indicator that turns blue when a solution becomes basic.
Part C: In the previous reaction, if you add a small amount of cyanide before adding the
Cu2SO4, the solution does not turn blue. What is a reasonable explanation?
a) The cyanide ion displaces the copper ions in the cytochrome c oxidase and stops the redox reaction.
b) The cyanide ion keeps the pH of the solution high. So the Cu2SO4 pH indicator does not show the decrease in pH.
c) The cyanide ion prevents the formation of ozone.

Answer 1

Answer:

1) magnesium chloride

2) b) The copper is getting oxidized from Cu+ to Cu2+ and turns blue.

Explanation:

The work published by David N. Frick, Sukalyani Banik, and Ryan S. Rypma in J Mol Biol. 2007 Jan 26; 365(4): 1017–1032 clearly shows that divalent metal ions of group 2 such as Mg^2+ play an important role in ATP hydrolysis. Addition of EDTA decreased the rate of hydrolysis of ATP (due to sequestration of the divalent ion of group 2) indicating an active participation of divalent ions in the process.

2) The copper I ion is colourless because it is a d^10 specie. However, when it is oxidized to Cu^2+, a blue colour appears in the solution.