What are the biochemical basis of cyanide poisoning?

To understand how cyanide poisoning works, you need to know what ETS is.

ETS (electron transport system) is a series of protein complexes in the inner mitochondrial membrane. ETS utilises the NADH and FADH2 to form ATP.

It consists of 5 complexes:

• Complex I : NADH dehydrogenase
• Complex II : Succinate dehydrogenase
• Complex III : Cytochrome c reductase
• Complex IV : Cytochrome c oxidase
• Complex V : ATPase or F0-F1 complex

Illustration:

ETS needs to work at all times and should not stop. If it stops, the organism will die.

Cyanide inhibits the Cytochrome c oxidase or complex IV of the ETS. Due to this, the ETS stops which leads to death of the organism.