Factors affecting Enzyme Actvivity

Question 1

What is the importance of enzyme shape?

Answer 1

It determines the shape of the active site, which determines their function.
Any changes in the enzyme shape will affect the enzymatic yield

Question 2

List the factors affecting enzyme activity

Answer 2

Temperature, pH, concentration of substrates, concentration of enzymes, presence of inhibitors

Question 3

what is the preferred pH of enzymes

Answer 3

6-8
Pepsin in the stomach (~2)
Trypsin in the small intestine (~8)
If the pH is too low/high (outside it’s optimal range), the enzyme will denature

Question 4

define “Denatured protein”

Answer 4

Protein that has lost its normal configuration and its ability to form an enzyme substrate complex

Question 5

Temperature decrease

Answer 5

Lowering the temperature lowers the rate of activity (does not usually denature the enzyme)

Question 6

What temperature do human enzymes start to denature

Answer 6

above ~40 degrees

Question 7

Substrate concentration increases

Answer 7

Amount of product increases. The rate of product formation will usually increase too.
After a certain concentration, the rate won’t increase anymore, as all the enzymes are “saturated” with substrates and can’t work any faster

Question 8

Temperature Increase

Answer 8

moderately, raises the rate of reaction
Largely, will denature the enzyme, which will lower the reaction rate

Question 9

Substrate concentration decreases

Answer 9

The rate of product formation will generally decrease

Question 10

Enzyme concentration increases

Answer 10

The more enzymes added, the more product produced
Rate of product formation increases

Question 11

Enzyme concentration decreases

Answer 11

The less enzymes, the less products produced
The rate of product formation decreases

Question 12

What does concentration limit

Answer 12

the overall rate of reaction
Rate will only level off if you run out of substrate (usually not the case)

Question 13

What are inhibitors

Answer 13

molecules that bind to the enzyme in some way to prevent/reduce the rate of substrate binding to the enzyme

Question 14

competitive inhibition

Answer 14

Molecule that looks like the substrate can compete for a place where the substrate binds to the enzyme, slowing down the reaction rate
The inhibitor binding to E can be reversible or irreversible
More inhibitors = lower reaction rate = lowering products made

Question 15

Non-competitive Inhibition

Answer 15

Inhibitor binds to another place on the enzyme, not on the active site (may look different from the substrate)
Binding causes enzyme to change shape at the active site so substrate cannot bind
Binding may be reversible or non-reversible
Also known as “allosteric” inhibition

Question 16

Inhibition can also be chemicals introduced into the system from outside

Answer 16

Can act as medicines or poisons
Ex. Penicillin, a medicine that kills bacteria, works by binding irreversibly to the enzyme that makes bacterial cell walls
HCN (hydrogen cyanide), lethal irreversible inhibitor of enzyme action in humans

Question 17

heavy metals

Answer 17

Lead and other heavy metals (mercury, cadmium) are non-competitive inhibitors that cause poisoning when they bind irreversibly to enzymes and make them denature

Question 18

reversible imhinition

Answer 18

often used as a normal way of slowing down metabolic pathways

Question 19

Thyroxin

Answer 19

Thyroid hormones (T4 and T3) increase the metabolic rate of cells
They stimulate all organs to metabolize at a faster rate
Production of thyroxin(e) requires iodine