Enzymes

Question 1

How can you increase a rate of reaction?

Answer 1

Temperature
Concentration
However annoy change these in the body
Enzymes are biological catalysts

Question 2

What is Vmax?

Answer 2

Maximal rate when all enzyme active sites are saturated with substrate, this depends upon enzyme concentration

Question 3

What is Km?

Answer 3

Units of substrate concentration and gives half maximal velocity
Gives measure of affinity of an enzyme for its substrate
Low Km = high affinity
High Km = low affinity

Question 4

What is 1 unit for Vmax?

Answer 4

Amount of enzyme that converts 1 micromol of product per min under standard conditions

Question 5

What are the intercepts on a Lineweaver-Burk plot?

Answer 5

X intercept = -1/Km
Y intercept = 1/Vmax
Slope = Km/Vmax

Question 6

What are enzyme inhibitors?

Answer 6

Molecules that slow down or prevent an enzyme reaction, including drugs

Question 7

What are irreversible enzyme inhibitors?

Answer 7

Bind tightly
Form covalent bond
E.g. nerve gas

Question 8

What are reversible enzyme inhibitors?

Answer 8

Non-covalent
Can freely dissociate
Competitive - binds at active site, affects Km not Vmax
Non-competitive - binds at active site on enzyme, affects Vmax but not Km

Question 9

How do competitive inhibitors work?

Answer 9

Resemble substrate and binds to active site, reducing proportion of enzyme molecules bound to substrate
E.g. TAMIFLU for influenza virus

Question 10

How do non-competitive inhibitors work?

Answer 10

Bind at an alternative site and decreases turnover number of enzyme, lowering Vmax
Compounds binding outside active site can also activate rather than inhibit
Have same Km but Vmax decreases