Enzymes

Question 1

What are the three ways that enzymes can reduce activation energy?

Answer 1

Entropy reduction, Desolvation, Induced fit

Question 2

What is entropy reduction?

Answer 2

Enzyme positions substrate so it’s in the correct orientation to fit - reducing entropy

Question 3

What is desolvation?

Answer 3

Water surrounding the enzyme and substrate make it energetically favourable for the substrate to enter the enzyme, pushing water away

Question 4

What is induced fit?

Answer 4

Enzyme having a conformational change to fit the substrate better after its bound

Question 5

What does the Michaeles-menten plot tell us?

Answer 5

The amount/conc. of substrate and the rate of reaction

Question 6

What does Km tell us on the Michaeles-menten plot?

Answer 6

Km = substrate conc. at 1/2Vmax

Question 7

What does Vmax tell us?

Answer 7

The maximum velocity of the equation once all the enzymes have been used up - plateaux

Question 8

What does the change in Km tell us?

Answer 8

Low Km tells us that the reaction doesn’t require a lot of substrate - faster reaction. High Km tells us the reaction requires a lot of substrate - slower reaction.

Question 9

What does change in Vmax tell us?

Answer 9

Higher Vmax - faster enzyme. Lower Vmax - slower enzyme

Question 10

What are 5 factors that effect enzyme inhibition?

Answer 10

Temp, pH, Enzyme conc. Substrate conc. and inhibition

Question 11

What are the 2 types of enzyme inhibition?

Answer 11

Competitive and non-competitive

Question 12

What happens during competitive inhibition? (Vmax and Km)

Answer 12

Inhibitor binds directly to the active site, blocking a substrate from binding. Vmax stays the same but Km decreases

Question 13

What happens during non-competitive inhibition? (Vmax and Km)

Answer 13

Inhibitor binds to alternative site on enzyme, changing the shape of the active site. Vmax decreases as not enough enzyme, but Km stays the same (as Vmax decreases in inhibited reaction)

Question 14

Why do we measure enzymes?

Answer 14

Many reasons including detecting diseases and deficiencies

Question 15

What 8 factors affect enzyme activity?

Answer 15

Age, race, gender, time of day, disease, genetics, pregnancy, drugs

Question 16

Give some examples of when enzymes would be released

Answer 16

Hypoxia, cellular damage, physical damage

Question 17

What is an enzyme assay?

Answer 17

A laboratory technique used to measure enzyme activity. It must be optimised to the specific requirements of the enzyme we are measuring

Question 18

How do we analyse enzymes in a lab?

Answer 18

We look at plasma/ serum samples. We measure the rate of an enzyme-substrate reaction

Question 19

What is an issue with enzyme measurement in labs?

Answer 19

Enzymes each have a specific optimum requirements, incl. pH and temp.

Question 20

What are isoenzymes?

Answer 20

Enzymes which have the same exact function but differ in structure

Question 21

Why does Phenylketonurea occur in humans?

Answer 21

Inability to break down amino acid phenylananine (using phenylalanine hydroxylase enzyme)

Question 22

What does reaching Vmax imply?

Answer 22

substrate occupies all available active sites of the enzyme

Question 23

What does denaturation refer to?

Answer 23

Weak bonds (hydrogen bonds) that maintain the secondary, tertiary and quaternary structures are lost but the covalent links between amino acids is retained.

Question 24

What does isomerase do?

Answer 24

Transfers groups within a molecule, forming an isomer