How does Cyanide block the electron transport system?

[ambzrose]

How do deadly chemicals like Cyanide, block the electron tranport sytem??

 

[gumbythescientist]

I don't really feel like explaining it right now but this link might be of some use

http://www.ruf.rice.edu/~bioslabs/s...s/when-did-mitochondria-evolve/"]mitochondria/mitopoisons.html[/url]

 

[Renge Ishyo]

Via the link above:

A concentration of 1 mM KCN is sufficient to inhibit oxygen consumption by mitochondria from a vertebrate source by >98%.

Well there you go. The driving force force for the electron transport chain in the mitochondria is the presence of oxygen at the end of the chain to accept the hydrogens/electrons. No oxygen, and the whole Krebs cycle shuts down (it is the same as if you are suffocating in that respect).

This can (and probably has been) tested by seeing if CN will still have the same effect on bacteria that can ferment (respiration without the need for oxygen) and that might indirectly affirm this, but I don't have any first hand knowledge of this sort of thing.

 

[Ouabache]

That reference mentions that it inhibits oxygen consumption and has something to do with cytochrome oxidase. I remember from biochem, that carbon monoxide has a stronger affinity to hemoglobin versus oxygen and competitively inhibits oxygen uptake.. I wonder how CN inhibits oxygen uptake? (time to go dig out my biochem book)

 

[Renge Ishyo]

This website offers a somewhat clearer statement of the mechanism involved, and even a treatment of sorts:

http://www.manbir-online.com/diseases/cyanide.htm

It seems like this is a similar idea to Carbon Monoxide poisioning (where it binds and inhibits the ability for Oxygen to bind), only this seems to take place with an enzyme specific to the mitochondria.