Enzymes and Bioenergetics

Question 1

Enzymes do this (4):

Answer 1

1. )Lower Ea
2. ) Provide proximity and orientation of reactants,
3. ) Ensure specificity of Substrates and Products
4. ) Stabilize transition complex

Question 2

What is the important function of Hexokinase?

Answer 2

Hexokinase links the hydrolysis of ATP to the phosphorylation of glucose in an energetically favorable reaction.

Question 3

Enzymes [ ] reaction rates and [ ] delta G

Answer 3

Increase; don’t affect

Question 4

Concerning reaction rates, V = ?

Answer 4

Vmax[S] /

Km + [S]

Question 5

What is Km?

Answer 5

Km is the Michaelis constant, the [S] at which v = ½ Vmax

Question 6

What is Pyruvate Kinase’s role, what are its forms, and where are they located?

Answer 6

1.) It’s the last enzyme in glycolysis (glucose –> pyruvate)
2. and 3.)
PK-M1: Most tissues
PK-M2: Embryonic tissue, cancer
PK-L: Liver
PK-R: Red blood cells

Question 7

What is the last reaction in Glycolysis?

Answer 7

PEP + ADP ———> Pyruvate + ATP

PK

Question 8

What’s does a lower Km result in for enzymes?

Answer 8

Higher activity levels of the enzyme when compared to an enzyme with a higher Km.

Question 9

Competitive inhibitors [ ] vmax and [ ] Km.
Graphically what does that mean?

Answer 9

Don’t change, increase

They also have same y intercept on MM inverse graph.

Question 10

What are some examples of competitive inhibitors?

Answer 10

Substrate and some transition state analogs

Question 11

Noncomptetive inhibitors [ ] Vmax, and [ ] Km

Answer 11

Decrease, don’t change

Question 12

What are some examples of noncompetitive inhibitors?

Answer 12

Suicide inhibitors and some transition state analogs

Question 13

How do Allosteric inhibitors change a MM curve and how are vmax and Km affected?

Answer 13

Hyperbolic to sigmoidal and both vmax and Km may change.