Module 6 - 2

Question 1

What are Binding Effects/transition state stabilization?

Answer 1

Increased interaction of enzyme and substrate.

Question 2

What is Transition State (TS) Stabilization?

Answer 2

Essence of catalysis is stabilization of the transition state.

Question 3

How does the enzyme distort the substrate?

Answer 3

Forces it toward the transition state.

Question 4

What is the active site complementary to?

Answer 4

Transition-state in shape and chemical character.

Question 5

How tightly do enzymes bind their transition states compared to their substrates?

Answer 5

1010 to 1015 times more tightly.

Question 6

What must the active site be to ensure specificity?

Answer 6

Similar enough to substrate.

Question 7

What must the active site be to promote change?

Answer 7

Different enough from substrate.

Question 8

What are Transition State Analogs?

Answer 8

Stable compounds resembling unstable transition states.

Question 9

What are Competitive Inhibitors?

Answer 9

Molecules that bind to the active site of an enzyme.

Question 10

What do Competitive Inhibitors resemble?

Answer 10

The substrate molecule.

Question 11

What are the potential therapeutic applications of Transition State Analogs?

Answer 11

As competitive inhibitors.

Question 12

What is Enzymatic Catalysis?

Answer 12

Enzyme acts upon substrate to promote formation of product.

Question 13

What do active sites often contain?

Answer 13

Chemically reactive side chains.

Question 14

What are the polar, ionizable side chains involved in chemical catalysis?

Answer 14

Asp, Glu, His, Cys, Tyr, Lys, Arg, and Ser.

Question 15

What are the two commonly observed mechanisms of chemical catalysis?

Answer 15

Acid/base Catalysis and Covalent Catalysis.

Question 16

Acid/base Catalysis and Covalent Catalysis.

Answer 16

Reaction acceleration achieved by catalytic transfer of a proton.

Question 17

What can the side chains of some amino acids act as?

Answer 17

Either bases or acids.

Question 18

What amino acid is often involved in acid/base catalysis?

Answer 18

Histidine.

Question 19

What influences the pKa of a functional group?

Answer 19

Chemical microenvironment.

Question 20

What is covalent catalysis?

Answer 20

Substrate is covalently bound to enzyme.

Question 21

What is the mechanism of covalent catalysis?

Answer 21

It involves two steps: forming a covalent linkage to the enzyme and regenerating the free enzyme.

Question 22

What is the role of functional groups of amino acids in acid/base catalysis?

Answer 22

They have different pKas within the active site which make them more suitable for acid/base catalysis.

Question 23

What is sucrose phosphorylase?

Answer 23

An enzyme that catalyzes the conversion of sucrose to fructose and glucose-1-P.

Question 24

What are the steps involved in sucrose phosphorylase reaction?

Answer 24

Step 1: Glucosyl residue is transferred to enzyme. Step 2: Glucose is transferred to phosphate.

Question 25

What is enzyme kinetics?

Answer 25

The study of the velocity of reactions.

Question 26

How is the velocity of a reaction quantified?

Answer 26

As the change in concentration of product over time.

Question 27

What are the units of enzyme kinetics?

Answer 27

Concentration over time, for example mmoles/sec or moles/min.

Question 28

What variables can influence enzyme activity?

Answer 28

Temperature, pH, and any variable that influences protein structure.

Question 29

What is the temperature sensitivity of enzymes?

Answer 29

Enzymes can have different optimum temperatures.