ADD - Enzymes (2)

Question 1

What is the reaction velocity equal to?

Answer 1

Rate

Question 2

Why is a maximum velocity (Vmax) reached?

Answer 2

All enzyme active sites are filled with substrate

Question 3

What is Km?

Answer 3

Substrate concentration for rate to be 1/2 Vmax

Question 4

What do enzymes turn an intermolecular reaction into?

Answer 4

A faster intramolecular one

Question 5

What do enzymes do to speed up the reaction?

Answer 5

-bring substrates closer together
-hold them in the optimal orientation so they react with each other

Question 6

What states do all reactions pass through?

Answer 6

Pass through transition states + sometimes through intermediates

Question 7

Why do transition states exist on very short femtosecond timescales?

Answer 7

Can’t isolate them

Question 8

Are transition states or intermediates more stable?

Answer 8

Intermediates
-they can be isolated

Question 9

What do enzymes prefer to bind to and why?

Answer 9

Transition states as they facilitate their formation

Question 10

What is teh favoured binding form of a molecule for an enzyme and why?

Answer 10

S‡ - transition state. It reduced the activation energy

Question 11

Do enzymes bind tightly or loosely to their substrates?

Answer 11

Don’t bind too tightly

Question 12

When enzymes are bound non-optimally, what is it called?

Answer 12

Stressed

Question 13

Is the enzyme strained or unstrained when bound?

Answer 13

Strained, but strain is relieved when the transition state is reached

Question 14

What are the common steps that recur in enzyme catalysed reactions that further enhance rate?

Answer 14

-general acid-base catalysis
-covalent catalysis
-use of metal ions in catalysis

Question 15

What does general acid-base catalysis involve?

Answer 15

-donation of a proton by a group on the enzyme acting as an acid
OR
-abstraction of a proton by a group on the enzyme acting as a base