One of the many remarkable enzymes in the human body is carbonic anhydrase, which catalyzes the interconversion of carbon dioxide and water with bicarbonate ion and protons. If it were not for this enzyme, the body could not rid itself rapidly enough of the CO2 accumulated by cell metabolism. The enzyme catalyzes the dehydration (release to air) of up to 107 CO2 molecules per second. Which components of this description correspond to the terms enzyme, substrate, and turnover number?

Verified step by step guidance

1. Identify the enzyme: In the given description, 'carbonic anhydrase' is mentioned as catalyzing a reaction. Therefore, carbonic anhydrase is the enzyme.
2. Identify the substrates: The substrates are the molecules that the enzyme acts upon to catalyze a reaction. In this case, the substrates are 'carbon dioxide and water' on one side of the reaction and 'bicarbonate ion and protons' on the other side.
3. Understand the term 'turnover number': Turnover number is a measure of the number of substrate molecules an enzyme can convert into product per second when the enzyme is fully saturated with substrate. It reflects the catalytic activity of the enzyme.
4. Relate turnover number to the enzyme's activity: According to the description, carbonic anhydrase can catalyze the dehydration of up to 10^7 CO2 molecules per second. Thus, the turnover number for carbonic anhydrase is 10^7.
5. Summarize the correspondence: The enzyme is carbonic anhydrase, the substrates are carbon dioxide and water (reactants) and bicarbonate ion and protons (products), and the turnover number is 10^7.

Key Concepts

Enzyme

An enzyme is a biological catalyst that accelerates chemical reactions in living organisms. It achieves this by lowering the activation energy required for the reaction to occur, thus increasing the reaction rate. Enzymes are typically proteins and are highly specific, meaning they only catalyze particular reactions involving specific substrates.

Substrate

A substrate is the reactant molecule upon which an enzyme acts. In the context of the reaction catalyzed by carbonic anhydrase, the substrates are carbon dioxide (CO2) and water (H2O), which are converted into bicarbonate ions (HCO3-) and protons (H+). The interaction between the enzyme and its substrate is crucial for the enzyme's catalytic function.

Turnover Number

The turnover number, often denoted as kcat, is a measure of the catalytic activity of an enzyme. It represents the maximum number of substrate molecules converted to product by a single enzyme molecule per unit time, under optimal conditions. In the case of carbonic anhydrase, the turnover number indicates its remarkable efficiency, as it can catalyze the conversion of up to 10^7 CO2 molecules per second.