Metabolic Poisons

Metabolic Poisons
Metabolic Poisons work by inhibiting the action of enzymes involved in Metabolic processes, causing a disturbance in the organism in its ability to function.

ARE NOT:
Substances that target neurotransmission/muscle contraction or substances that burn or ‘digest’ tissue.

They can be commonly referred to as "enzyme inhibitors" as they prevent enzymes from performing their necessary functions.
Uncoupling Agents
Electron Transport System Inhibitors (ETS Inhibitors)
Overview of Cellular Respiration
Metabolic Poisons
Organic Compounds + Oxygen
Cellular Respiration-
Cells extract oxygen from the blood and transform the energy in sugar molecules into a useful form of energy for cells.
Enzymes-
Macromolecules (mostly proteins) that serve as catalysts, agents that increase the rate of the reaction without being consumed within the reaction.
Inhibitors-
Molecules that bind to an enzyme to decrease their activity.
Poisons
- Substances that cause disturbances or interfere with normal bodily functions.
Metabolic Poisons-
Substances that interfere with Energy Metabolism.
Uncoupling Agents-
A condition in which rate of electron transport can no longer be regulated by an intact chemiosmotic gradient.
Oligomycin-
Antibiotic that binds to ATP synthase and blocks off the proton channel, inhibiting oxidative phosphorylation.
Examples
Potassium Cyanide




Arsenic
For more information on Metabolic Poisons, check out our wiki page!

http://drhmths1314.pbworks.com/w/page/70738257/Metabolic%20Poisions

Or, you can check out these pages!
http://alevelnotes.com/Enzyme-Inhibitors/148

http://www.yorku.ca/dkwilson/3050%20Week%2011.pdf

http://www.ruf.rice.edu/~bioslabs/studies/mitochondria/mitopoisons.html

Th
Key Terms
Carbon dioxide + Water + Energy
C6H12O6 + 6 O2
6 CO2 + 6 H2O + Energy (ATP + Heat)
Process
Part 1: Glycolysis
Occurs in the cytoplasm

Input:
Glucose

G3P
Uses
2 molecules of ATP
Output:
G3P

Pyruvate
Produces
4 molecules of
ATP
Net Payoff-
2 ATP
2 Pyruvate
2 NADH

Part 2: Krebs Cycle
Occurs in the
mitochondrial matrix

Input:
Pyruvate (2 per glucose)

Output
(per glucose)
:
6 CO2
8 NADH
2 FADH2
2 ATP (via substrate-level
phosphorylation)

Part 3: Electron Transport Chain
Occurs in the
mitochondrial matrix

Input:
8-10 NADH
2-4 FADH2

Output
32-34 ATP
Overall Output of Respiration: Glucose 36-38 ATP

What are they?
What are the different types?
3 main types:
-
ETS Inhibitors
: Binds somewhere on the electron transport chain, preventing electrons from being passed from one carrier to the next.
-
Uncoupling agents
: The rate of electron transport can no longer be regulated by an intact chemiosmotic gradient.
-
Oligomycin:
Binds to ATP synthase and blocks the proton channel, inhibits oxidative phosphorylation.
- Binds to ETS, prevents electrons from being passed from one carrier to the next.
- They all act specifically, in which each inhibitor binds a particular complex in the ETS
- Irreversible inhibition: Results in a complete stoppage of respiration via the blocked pathway.
- Competitive Inhibition allows some oxygen consumption, but prevents maintenance of a chemiosmotic gradient. Hence, the addition of ADP can have no effect on respiration.
- Electron transport inhibitor can block respiration specifically along the NADH pathway, along the succinate pathway, or along the pathway that is common to both routes of electron entry.
Oligomycin
Examples
2,4-Dinitrophenol
Carbonyl cyanide p-[rifluoromethoxyl]-phenyl-hydrozone (FCCP)
Sources
- Rate of electron transport can no longer be regulated by an intact chemiosmotic gradient.
- Different from Electron Transport System inhibition, since bypassing the block restores the gradient.
- ETS is uninhibited due to complete and irreversible dissipation of the chemiosmotic gradient.
Oligomycin
- Acts by binding ATP synthase in such a way as to block the proton channel.
- Mechanism by which oligomycin inhibits oxidative phosphorylation.
- No effect on state IV respiration, that is, it has no direct effect on electron transport or the chemiosmotic gradient, but prevents state III respiration completely.
- Effects take awhile to be shown.