Enzyme Structure & Function

Question 1

Why isn’t gasoline considered a catalyst when poured over a fire?

Answer 1

Although it does encourage the combustion rxn, it is consumed in the process. Enzymes are NEVER consumed

Question 2

Of the 4 catalytic strategies, when would covalent catalysis occur?

Answer 2

During an electron transfer

Question 3

Of the 4 catalytic strategies, which one results in the movement of H+ molecules?

Answer 3

the transfer of protons is Acid/base catalysis

Question 4

Of the 4 catalytic strategies, what does electrostatic catalysis lead to? Give an example

Answer 4

Electrostatic catalysis results in a charge balance (e.g. DNA polymerase utilizing Mg2+ molecules to balance neg. charge on DNA)

Question 5

Enzymes catalyze biochemical reactions by lowering what quantity associated with the rxn?

Answer 5

Activation energy

Question 6

Phosphoglucomutase, which catalyses the formation of glucose-6-phosphate from glucose-1-phosphate, is best classified as which of the following enzyme type?

Answer 6

Isomerase (G6p is an isomer of G1P)

Question 7

Which of the following molecules CANNOT be classified as an enzymatic cofactor?

1. Mg2+
2. Valine
3. Heme
4. FAD

Answer 7

Valine. (it functions as a co enzyme since it is an amino acid)

Question 8

In order to analyze the catalytic effect of two different enzymes on the same chemical reaction, it is best to compare what quantity?

Answer 8

Difference in transition state energies

Question 9

The active site of an enzyme E, which catalyzes a reaction X, is partially denatured: which of the following quantities associated with X is most likely to be affected by the partial denaturation of E compared to the native form of E?

Answer 9

The rate constant k

Question 10

The induced fit model of enzyme binding states that which of the following molecules alters the enzyme active site to match the shape of the substrate more closely?

Answer 10

The substrate itself

Question 11

How is the induced fit model unique in its ideology?

Answer 11

The induced fit model says that the active site is warped to bind the substrate more tightly during the course of substrate binding

Question 12

Which of the following enzyme types catalyzes the formation of a single bond between two substrates through the elimination of H2O?

1. Ligase
2. Hydrolase
3. Isomerase
4. Lyase

Answer 12

Ligase (only one here that made bonds)

Question 13

Enzymes undergo a decrease in catalytic efficiency in the presence of excess temperature, but can regain this efficiency once temperature returns to normal: this suggests that increased temperature does NOT disrupt which of the following aspects of enzyme structure?

1. Peptide bonds
2. Hydrogen bonds
3. VDW forces

Answer 13

Peptide bonds. They are the intrinsic makeup of enzymes so if these were disrupted, the enzyme would be nonfunctional.

Question 14

Local conditions can affect the specificity of an enzyme for its substrate, and thus the enzymes catalytic ability: which of the following alterations would most likely NOT affect an enzyme in this manner?

1. Increased temp
2. Decreased pH
3. Increased substrate
   concentration

Answer 14

Increased substrate concentration