Written by Merel Dagher (PEACE Advisor)
Glutamic Acid has three ionizable groups, with the respective pKas of 2.10, 4.07, and 9.47.
a. Draw the structure of Glutamic Acid and label the pKas.
b. What is the net charge of glutamic acid at the following pHs? pH = 1, pH = 3, pH = 5, pH = 10
c. 1 ml of 5 M NaOH is added to 10 ml of 0.10 M glutamic acid. What is the pH of this solution?
d. What does the pH calculated in “c” tell us about the solution?
e. Following part c, an additional 1 ml of NaOH were added. How many moles of glutamic acid remain after this?
f. Now I add an additional 1 ml of NaOH. What is my new pH?
g. What does the pH found in “f” tell us about the solution?
h. Glutamate decarboxylase (GAD) is an enzyme that converts glutamate to GABA and CO2. Name three ways in which it catalyzes this reaction.
i. An inhibitor of GAD was introduced. It was found to decrease the velocity of the reaction, but didn’t affect the enzyme’s ability to bind Glu. What type of inhibitor is this?
j. Another inhibitor was introduced to a separate test tube. In this case, the inhibitor decreased the enzyme’s affinity for the substrate, but didn’t affect Vmax. What type of inhibitor is this?
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