Enzyme Kinetics 2

Question 1

What is an oxyanion hole ?

Answer 1

A pocket in the enzymes active site that stabilises a negatively charged oxygen atom on a reaction intermediate during catalysis

Question 2

What is enzyme inhibition?

Answer 2

The slowing down or stopping of an enzymes activity using inhibitors
There is reversible inhibition- competitive inhibition
and Irreversible inhibition

Question 3

What is competitive inhibiton ? What effects does it have ?

Answer 3

The inhibitor binds to the active site, competing with the substrate.
Vmax is unchanged
Km is increased

Question 4

What is Km apparent ?

Answer 4

The Km you measure during the presence of the inhibitor

Question 5

What is irreversible inhibition? What effects does it have ?

Answer 5

The inhibitor permanently blocks the active site
Normally covalent bonding which inactivates the enzyme permanently
Km stays the same
Vmax decreases

Question 6

What is edrophonium ?

Answer 6

Used in diagnosis of myasthenia gravis
A competive inhibitor of acetylcholinesterase

Question 7

Myasthenia gravis

Answer 7

Antibodies block acetylcholine receptors at NMJ so Ach cannot stimulate the muscle
Causes muscle weakness