LECTURE 10

Question 1

Do both endergonic and exergonic reaction have activation energies ?

Answer 1

YES

Question 2

Catalysis steps

Answer 2

1) substrates enter active site, enzyme changes shape to enfold the substances. (Induce fit)
2) substances held in active site by weak interactions
3) active site can lower Ea and speed run
4) substances are converted to products
5) products are released
6) active site is available for two new substrates

Question 3

Ways enzymes lower Ea ?

Answer 3

1) bringing reactants together, chemical interactions
2) physically stressing the substrate bonds. I induced fit shifts shape of enzyme-substrate complex. Bonding of bonds makes them easier to break
3) if favourable microenvironment for run, (cluster of side chains the enzymes active site create low PH “pocket” in neutral cytosol. —> facilitates transfer of H to the substrate
4) direct participation in chemical rxns. (Temporary bond between active sites and substrate and subsequent regeneration of active site amino acid chain after reactant leave active site).

Question 4

Factors that effect enzyme function

Answer 4

1) temperature
2) PH
3) cofactors and coenzymes
4) enzyme inhibitors

Question 5

Temperature effecting enzyme function

Answer 5

In general, enzymes work best at 35-40 C. Increasing chance of collision.

• above certain temp, activity drops.
• thermophilic archaea enzymes ( work at 70)

Question 6

What does to much thermal energy do to enzymes ?

Answer 6

Disrupts H-bonds, ionic bonds, and other weak interactions, that cause the enemy mess to lost its shape.

Question 7

PH effecting how enzymes function

Answer 7

Most enzymes work best at a ph of 6-8

Question 8

Cofactors and coenzymes effecting enzyme function

Answer 8

Many enzymes require additional components to function.

Question 9

Cofactors

Answer 9

Inorganic molecules (like ions for ex)

Question 10

Coenzymes

Answer 10

Organic, non-proteins, (vit B)

Question 11

If an enzyme Normally has a coenzyme, these conditions apply:

Answer 11

1) enzyme + coenzyme = holoenzyme (active)

2) enzyme alone = apoenzyme (non-functional

Question 12

Enzyme inhibitors effecting the function of enzymes

Answer 12

Certain chemicals selectively inhibit the actions of certain enzymes

I) competitive inhibitors

ii) non-competitive inhibitors

Question 13

Competing inhibitors

Answer 13

• have similar shape or the normal substrate and bonds to active site of enzyme.
• doesn’t participate in rxn.
• compete with real substrate for access to the enzyme

Question 14

Non competitive inhibitors

Answer 14

Inhibits the function of the bonding to different locations (non active site)

Effects shape and function of active site

Question 15

Non competive inhibitors effect :

Answer 15

A) the shape of the active site (prevents docking)

B) the function of the active site (with out interfering with substrate docking)

Question 16

Important distinction between non competitive and competitive inhibitors

Answer 16

Competitive inhibitors can be out completed by increasing the amount of substrates, NON competitive cannot.

Question 17

How are enzymes regulates

Answer 17

Allosterically

Question 18

Allosteric regulation

Answer 18

When proteins functions at one site is affected by the binding of a molecule to another site.

Question 19

What is another type of allosteric regulation

Answer 19

Non competitive inhibition

Question 20

Allo means

Answer 20

Different

Question 21

Steric means :

Answer 21

Spatial arrangement of atoms

Question 22

Molecule concentration can influence a reactant / product ratio

Answer 22

Concentrations of either products or reactants influences the progress of rxn, direction and short in equilibrium.

Question 23

The concentration for each reactant and product is related to

Answer 23

The free energy of the reaction