Enzymes - Michaelis-Menten Kinetics

Question 1

Enzyme Kinetics

Answer 1

This is the study of understanding rate of reaction and how it changes to various experimental parameters

Question 2

What may complicate enzyme kinetics?

Answer 2

Substrate concentrations changes during reaction in converstion to the product

Question 3

How can substrate change be determined?

Answer 3

Initial Rate V0

Question 4

What is the state of the substance at inital rate?

Answer 4

Enzyme is in nanomolar quantities whilst subtrate on 5-6 orders of amgnitude.

Question 5

How can [S] be limited to few precent?

Answer 5

If only hte begining of the reaction is monitred.

Question 6

What can inital rate be used to study

Answer 6

Inital rate as a funciton of [S] : at low substrate concentraitons, V0 increases near linearly with increasing [S]

Question 7

Maximum Velocity

Answer 7

This is where all enzymes at maximum spped at high substrate concentration

Question 8

How is ES complex formation described?

Answer 8

E + S <–>ES

Question 9

What are the two steps of a reaction?

Answer 9

E+S,<->ES
ES<–> E+P

Question 10

What does ES<–>E+P describe?

Answer 10

Complex break down forming enzyme and reaction product

Question 11

What do ES and E concentration differ depend on?

Answer 11

S concnetratnion, at low most enzyme in E form, where rate of activity is proportional to S as equilibrium favours more ES formaiton with S increase

Question 12

When does maximum velocity occur?

Answer 12

When al enzymes present are in ES complex formation, where further S increase does not affect rate due to enzyme saturation

Question 13

What is important to note when P is formed?

Answer 13

E is able to form ES again to catalyse another reaciton.

Question 14

Pre-Steady State

Answer 14

This occurs when there is a rapid burst of ES complexes forming in the beginning the process is slow because the ES is still forming, then it increases

Question 15

What does S and V0 relationship approach?

Answer 15

Rectangular hyperbola

Question 16

What does the MMK express?

Answer 16

Relationship between S and V0

Question 17

Michaelis-Menten Kinetics

Answer 17

This estimates enzyme kinetic parameters from reaction progress curves of substrates

Question 18

What is the MMK Equation?

Answer 18

V0=Vmax[S]/Km+[S]

Question 19

Michaelis Constant

Answer 19

This is as substrate concentration at which the rate of reaciton is half the maximum rate that can be achived under given conditions, that being where velocity of reaction is half Vmax

Question 20

What was MMK derivation initally base don?

Answer 20

Idea that enzymatic reactons rate limiting step is ES complxe breakdown to E

Question 21

What does KM describe?

Answer 21

Michaelis Constant

Question 22

What is the units of Km?

Answer 22

nmol L^-1

Question 23

Initial Velocity

Answer 23

This is the rate at which the reaciton proceeds at a given substrate concentraiton

Question 24

What is inital velocity determined by?

Answer 24

ES breakdown to form product: V0=K2[ES]

Question 25

What does Et represent?

Answer 25

Total enzyme content, whether E or ES, where E equals Et-ES

Question 26

What is ES formation rates govered by?

Answer 26

K1

Question 27

What is ES breakdown rate foverned by?

Answer 27

k-1+k2

Question 28

Steady-State Assumption

Answer 28

This is the concentraiton of the intermediates of a reaction remain the same even when the concentraiton of starting materials and products are hcanging

Question 29

What is the steady state assumption given by?

Answer 29

K1[ET]-[ES]))[S]=k-1[ES]+k2[ES]

Question 30

What does the MM equation descrie?

Answer 30

The rate equation for a one-ubstrate enzyme-catalysed reaction, relating inital velocity, maximum velocity and inital substrate concentraiton with the michaelis constant.

Question 31

How do enzymes realte to MMK?

Answer 31

Most follow MM kinetics, except regulatory enzymes, hoever some exhibiting beyond the two steps can follow these kinetics

Question 32

What are the assumption s of MM kinetics?

Answer 32

Reaction is assumed to be a single substrate reaction(inhibition concentraiton)#K2 assumes no reverse mechanism is present, like product inhibition or reverse catalysis.

Question 33

What is the doubling relationship between S and B?

Answer 33

When KM is 100nML^-1 and [S] are 1 and 2, Vmax being constant, then Vmax[1]/100+[1] Vmax[2]/100+[2]

Question 34

When is Vmax constant?

Answer 34

If [E] is the same

Question 35

Why does MM form a rectnagular hyperbola?

Answer 35

Initial linear increase limited when S