cartoon diagram of the enzyme inhibition

1. Enzyme Inhibition (Mechanism)
I
I
S
S
S I
I
I II
S
Competitive Non-competitive Uncompetitive
E
E
Different site
Compete for
active siteInhibitor
Substrate
CartoonGuideEquationandDescription
[II] binds to free [E] only,
and competes with [S];
increasing [S] overcomes
Inhibition by [II].
[II] binds to free [E] or [ES]
complex; Increasing [S] can
not overcome [II] inhibition.
[II] binds to [ES] complex
only, increasing [S] favors
the inhibition by [II].
E + S→ES→E + P
+
II
↓
EII
←
↑
E + S→ES→E + P
+ +
II II
↓ ↓
EII+S→EIIS
←
↑ ↑
E + S→ES→E + P
+
II
↓
EIIS
←
↑
E
I
S X
Dhirendra Kumar Chauhan M.Sc. Zoology DDUGU Gorakhpur

2. Km
Enzyme Inhibition (Plots)
I II Competitive Non-competitive Uncompetitive
DirectPlotsDoubleReciprocal
Vmax Vmax
Km Km’ [S], mM
vo
[S], mM
vo
II II
Km [S], mM
Vmax
II
Km’
Vmax’Vmax’
Vmax unchanged
Km increased
Vmax decreased
Km unchanged
Both Vmax & Km decreased
II
1/[S]1/Km
1/vo
1/Vmax
II
Two parallel
lines
II
Intersect
at X axis
1/vo
1/Vmax
1/[S]1/Km 1/[S]1/Km
1/Vmax
1/vo
Intersect
at Y axis
= Km’
Dhirendra Kumar Chauhan M.Sc. Zoology DDUGU Gorakhpur