Enzyme Kinetics Flashcards Preview

Principles: biochemistry > Enzyme Kinetics > Flashcards

Flashcards in Enzyme Kinetics Deck (44)
Loading flashcards...
1

what is Vmax?

the maximum velocity of an enzymes - when it cannot work any faster

2

what is the Km?

the substrate concentration at Vmax over 2

3

what is the V a measure of?

the moles of substrate converted to product per second

4

the michaelis - menten is a _____ shaped graph

hyperbolic

5

as the Km increases the affinity of the enzyme for the substrate ____

decreases

6

in the MM Model what does K1 represent ?

E and S forming ES
the forward rate constant for enzyme association with the substrate

7

in the MM Model what does K2 represent ?

ES (binding complex) forming E and P (product)

s the forward rate constant of enzyme conversion of substrate to product (P)

8

in the MM Model what does K-1 represent ?

ES going back to E and S

k-1 is the backwards rate constant for enzyme dissociation from the substrate.

9

What is the michaelis constant equation Km?

Km = k-1 and k2
-------------------------
K1

basically - dissociation over association

10

BIG “BUT” - It is not straightforward to determine Vmax and KM from such a graph because the kinetics are not ______ - reaction velocity never quite reaches true ______ !

BIG “BUT” - It is not straightforward to determine Vmax and KM from such a graph because the kinetics are not linear - reaction velocity never quite reaches true Vmax !

11

the michaelis menton equation describes the ___of catalysis as a function of _____ concentration. This describes a hyperbola

describes the rate of catalysis as a function of substrate concentration. This describes a hyperbola

12

what is the michaelis menton equation?

V= Vmax[S]
-----------------
Km + [S]

13

what is the straight line equation?

1 = Km . 1 + 1
-- ------ --- --------
V Vmax [S] Vmax

14

in the lineweaver burk plot Vmax =

Vmax = intersection of the straight line with the Y axis

15

in the lineweaver burk plot Km=

KM = intersection with the X axis

16

the lineweaver burk plot is a _____ _____ plot

double reciprocal

17

A ___ KM means that an enzyme
only needs a little substrate to
work at half-maximal velocity

low

18

A ___ KM means that an enzyme
needs a lot of substrate to work at
half-maximal velocity

high

19

Enzymes can display the same ___
and have different __

Vmax and Km

20

a clinical examples of why Vmax and Km matter would be glucose homeostasis and _____

MODY
maturity onset diabetes of the young

21

both ___ and ___ catalyse the reaction of glucose + ATP ----> glucose-6-phosphate + ADP

hexokinase and glucokinase

22

hexokinase has a ___ Km for glucose

low

23

what does the ____ Km for hexokinase mean it can do?

Low KM maintains energy production in red
blood cells by glycolysis even if glucose
levels fall dramatically

24

where is hexokinase found?

RBCs

25

where is glucokinase found?

liver and pancreas

26

glucokinase has a ____ Km for glucose

high

27

what does the ___ Km for glucose mean glucokinase is able to do

high, High KM enables glucose sensing & homeostasis. It’s abundance in liver is regulated by insulin. Excess blood glucose is metabolised

28

what happens in MODY?

get loss of glucokinase activity and this means loss of insulin-mediated glucose homeostasis

29

look at slides for other clinical effetc - hypoxia and stuff

.

30

what is revesible competitive inhibition

Inhibitor binds to the active
(catalytic) site & blocks
substrate access.

Orthosteric Inhibition - at the same site