Enzymes and Proteins

Question 1

What are the 2 types of inhibitors

Answer 1

competitive and non-competitive

Question 2

Outline competitive inhibitors

Answer 2

• bind at the active site of the enzyme
• they have a similar shape to the substrate
• prevent substrate from binding to active site

Question 3

Solution for competitive inhibitors

Answer 3

increasing the concentration of substrates, decreases the impact of competitive inhibition, as fewer of the inhibitors are able to bind to the active site

Question 4

What happens to the Vmax for competitive inhibitors

Answer 4

Vmax is not changed as there is still a substrate concentration where full enzyme activity can be achieved

Question 5

What happens to the Km for competitive inhibitors

Answer 5

The Km is increased as it takes a higher substrate concentration to reach Vmax

Question 6

Outline non-competitive inhibitors

Answer 6

• bind to the allosteric site of the enzyme
• alter the shape of active site and prevents the substrate to bind to the active site of enzyme

Question 7

Solution for non-competitive inhibitors

Answer 7

no solution: increasing the concentration of substrates doesn’t reduce the effect of the inhibition

Question 8

What happens to the Km for non-competitive inhibitors

Answer 8

Km remains unchanged

Question 9

What happens to the Vmax for non-competitive inhibitors

Answer 9

Vmax decreases

Question 10

What does Vmax mean/represent

Answer 10

refers to the point where all the active sites are saturated
- a low Vmax = high enzyme activity
- a high Vmax = low enzyme activity

Question 11

What does Km mean/represent

Answer 11

refers to the substrate concentration which is equal to half of its maximum value
- high Km = high concentration of substrate needed to saturate enzyme (low enzyme-substrate) affinity

Question 12

Define buffer

Answer 12

substances that resist changes in pH in addition of small amounts of acid or base

Question 13

What can act as a buffer

Answer 13

amino acids

Question 14

does an amino acid act as a buffer around its isoelectric point

Answer 14

no

Question 15

Why can amino acids act as buffers

Answer 15

they can accept and donate protons

Question 16

What are the assumptions made when calculating the ph of a buffer

Answer 16

• salt completely dissociates into its ions
• The concentration of the weak acid at equilibrium is approximately equal to the initial concentration of the weak acid

Question 17

What is UV-visible spectroscopy

Answer 17

a technique used in protein assays to measure the concentration of a protein in a sample

Question 18

What is product inhibition

Answer 18

Since metabolic processes often have multiple enzyme-catalysed steps, the end product of the whole process sometimes produces compounds that inhibit one of the enzyme-catalysed steps

Question 19

What types of bonds are responsible for competitive and non-competitive inhibitors when binding to the active site

Answer 19

competitive: IMFs
non-competitive: covalent bonds