9 - Energetics and Dynamics

Question 1

structure of an enzyme?

Answer 1

sachride interacting residue

catalytic residue

extended binding cleft

Question 2

steps of an ezyme reaction?

Answer 2

enzyme + substrate [binding]
enzyme subtrate complex
[catalysis]
Enzyme-product complex
[release]
enzyme + product

Question 3

understand an exergonic reaction and endergonic using Gibbs?

Answer 3

if G more than 0

• EXERGONIC
• energy is lost

if G less than 0

• ENDERGONIC
• energy not lost

Question 4

coupling energonic and exergonic?

Answer 4

.

Question 5

substrate factors that enzyme function depends on?

Answer 5

• localisation of sub
• orientation
• binding energy

Question 6

what step is the slowest step in a reaction?

Answer 6

K2
step from enzyme substrate –> enzyme + product

• K2 = Kcat

Question 7

what are the 3 assumptions of the michaelis-menten calc?

Answer 7

1. Reverse reaction is neglible
2. Only single Enzyme Substrate complex
3. Assume subtrate is in much more excess than enzyme and [S] isn’t affected

Question 8

understand initial rate and [S] graph?

Answer 8

.

Question 9

what is the Vmax and the eq?

Answer 9

theoretical max where enzyme is fully saturated [limiting factor]

Vmax = Kcat [E]t

Question 10

What is Vo

Answer 10

half the Vmax
cant be obtained as you don’t know the Vmax

so use m-m eq

Question 11

michealis menten eq?

Answer 11

Vo = Vmax [S] / Km + [S]

(Vmax is also Kcat[E]t)

Question 12

what is Km?

Answer 12

Michealis constant

[S] when reaction is 1/2 maximal

Question 13

how to find Km?

Answer 13

line where Vo meets curve then down to [S]

Question 14

what is Kcat?

Answer 14

Kcat is the slowest step so the K2 step

Question 15

what does a

• high Kcat value mean
• small Km value mean

Answer 15

high Kcat
- rapid turnover

small Km
- high substrate affinity