Exercise for Introduction to Enzymes |
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1. Each term in the first column of the table is required for the reaction catalyzed by the enzyme that is named. Classify terms by filling in the rest of the table. You may need to use your text for the last column.
Use these letters to classify the terms: (M) metal; (O) organic; (P) protein;
(N) non-protein; (C) prosthetic coenzyme; (S) co-substrate coenzyme
If a term is classified as metal or protein, it is not a coenzyme; in that case, write X in the last column.
Table 1: Classifying Parts of Enzymes |
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Term |
M or O |
P or N |
C or S |
Mg2+ – hexokinase |
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aspartate – chymotrypsin |
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biotin* – pyruvate carboxylase |
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NAD+ – lactate dehydrogenase |
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Zn2+ – carbonic anhydrase |
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FAD** – succinate dehydrogenase |
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2. The enzymes listed in Table 1 catalyze the reactions shown below. Classify each enzyme as a/n oxidoreductase, transferase, isomerase, lyase, hydrolase, or ligase. Then verify your classification by using the PDB identification number.
Hexokinase |
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Chymotrypsin |
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Pyruvate carboxylase |
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Lactate dehydrogenase |
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Carbonic anhydrase |
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Succinate dehydrogenase |
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Table 2: Classifying Enzymes |
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Enzyme and PDB ID |
Classification |
PDB Class |
Hexokinase 1HKG |
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Chymotrypsin 2GCH |
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Pyruvate carboxylase 1ULZ |
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Lactate dehydrogenase 1LDM |
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Carbonic anhydrase 2CAB |
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Succinate dehydrogenase 1NEK |
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3. The diagram below represents the changes in free energy for both the catalyzed and uncatalyzed reaction of A → X, with a transition state T. The ground energy state for A is on the left, and the ground energy state for X is on the right of the diagram.
Fill in the numbers in the table.
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Table 3: ΔG and ΔG† |
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| Reaction | A → X | X → A | |
| ΔG | |||
| ΔG† catalyzed | |||
| ΔG† not catalyzed | |||
