The Following PH Dependence Was Found for the Activity of a Certain

question 28

Multiple Choice

The following pH dependence was found for the activity of a certain enzyme-catalyzed reaction. If it is known that the only two ionizable residues in the active site are both glutamates, which conclusion can be drawn?

• A) The glutamates have different microenvironments which cause their pK_aʹs to differ.
• B) One of the glutamates must be amidated.
• C) Both glutamates have a pK_a equal to 5.0.
• D) Both glutamates are deprotonated during the reaction.

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Definitions:

Vaporization

The phase transition of a substance from a liquid to a gas, occurring through the processes of evaporation or boiling.

Calorie

The amount of heat energy required to raise the temperature of 1 g of water 1°C; equivalent to 4.184 joules. Compare with Kilocalorie.

pH Value

A numeric scale used to specify the acidity or basicity of an aqueous solution, with values ranging from 0 (most acidic) to 14 (most basic), and 7 being neutral.

Beer

A fermented beverage made from barley, hops, water, and yeast, commonly consumed worldwide.