book 1 (enzyme inhibitors)

Question 1

describe how competitive inhibitors work.

Answer 1

1. competitive inhibitors have similar 3D conformation to substrates
2. it competes with substrate for binding to the active site of enzymes
3. thus decreasing frequency of effective collisions between enzymes and substrates molecules
4. decreases the concentration of enzyme-substate complexes formed per unit time
5. decreases the concentration of products formed per unit time
6. rate of reaction decreases

Question 2

state the effect of substrate concentration on rate of reaction (competitive inhibitors)

Answer 2

1 the increase in substrate concentration increases the frequency of effective collisions between enzyme and substrates as compared to enzyme and inhibitors

2. this increases the formation of enzyme-substrate complexes compared to enzyme-inhibitor complexes
3. there will be increase in concentration of products formed per unit time
4. rate of reaction can still reach the maximum value at high substrate concentration

Question 3

describe how non-competitive inhibitors work

Answer 3

1. non-competitive inhibitors don’t have similar 3D conformation to the original substrates of enzymes
2. thus inhibitor binds to enzyme at a specific region other than the active site
3. this changes the 3D conformation of enzyme and alters the 3D conformation of active site
4. substrate no longer able to bind to enzyme active site
5. this decreases the frequency of effective collisions between enzymes and substrate molecules, thus decreasing the concentration of enzyme-substrate complexes formed per unit time, and decreases the concentration of products formed per unit time
6. thus decreasing rate of reactions

Question 4

state the effect of substrate concentration on the rate of reaction (non-competitive)

Answer 4

1. the increase in the substrate concentration cannot increase rate of reaction as the presence of non-competitive inhibitor renders a proportion of the enzyme molecule out of action
2. decreasing the effective enzyme concentration in the reaction mixture
3. rate of reaction cannot reach maximum value even at high substrate concentrations

Question 5

describe how allosteric inhibitors work

Answer 5

1. no similarity in 3D conformation to the original substrate of enzyme
2. allosteric inhibitors binds to one of the several allosteric sites on enzymes, altering the 3D conformation of active sites on that subunit and other subunits too
3. substrate unable to bind to the enzyme active sites
4. this decreases the frequency of effective collisions between enzymes and substrates, decreasing the concentration of enzyme-substrate complexes formed per unit time
5. decrease in concentration of products formed per unit time