Cyanide-insensitive respiration is a respiratory pathway found in the mitochondria of some plants, yeasts, and bacteria that is unaffected by cyanide. It involves an alternative oxidase (AOX) that allows electrons to bypass the cytochrome c oxidase in the electron transport chain. AOX is a homodimeric integral membrane protein that transfers electrons from ubiquinone directly to oxygen without proton pumping. This pathway releases energy as heat rather than generating a proton gradient for ATP synthesis. Cyanide-insensitive respiration is not found in animal cells.

1. CYANIDE INSENSITIVE RESPIRATION
Anju Katherin and Dr. Kayeen Vadakkan
Department of Biotechnology
ST.MARY’S COLLEGE, THRISSUR

2. CYANIDE INSENSITIVE RESPIRATION, ANJU KATHERIN, ST.MARY’S COLLEGE - THRISSUR
•Cyanide-insensitive respiration(or
resistant respiration) was discovered at the
beginning of 20th century in thermogenic
plants during anthesis and was later found to
be a typical feature of plant respiration . It is a
respiratory pathway, occuring only in
mitochondira of some plants, yeast , and
bacteria , that is unaffected by cyanide.

3. CYANIDE INSENSITIVE RESPIRATION, ANJU KATHERIN, ST.MARY’S COLLEGE - THRISSUR
•Cyanide-resistant respiration is not found in
animals
•The phenomenon of respiration resistant to
cyanide is connected with the presence of an
additional terminal oxidase-alternative
oxidase (AOX)
•AOX is an approximately 32-kDa homo
dimeric integral mitochondrial inner
membrane protein with a non heam di Fe
centre and two membrane spanning protein.

4. CYANIDE INSENSITIVE RESPIRATION, ANJU KATHERIN, ST.MARY’S COLLEGE - THRISSUR
•The flow of electrons from reduced
coenzymes to Ubiquinone is the same as in
usual mitochondrial electron transport chain.
•The electrons pass from UQ to a flavoprotein
Fpma and direct to a cyanide resistant
alternative oxidase and finally to O2
•In between UQ and oxygen a free energy
released as heat

5. CYANIDE INSENSITIVE RESPIRATION, ANJU KATHERIN, ST.MARY’S COLLEGE - THRISSUR

6. CYANIDE INSENSITIVE RESPIRATION, ANJU KATHERIN, ST.MARY’S COLLEGE - THRISSUR
•www.biologydiscussion.com/.../respiration.../cyanide-
resistant-respiration .
• Albert lehinger , David L. Nelson, Michael M.Cox
Lehinger principle of biochemistry second edition
Page no 495

7. CYANIDE INSENSITIVE RESPIRATION, ANJU KATHERIN, ST.MARY’S COLLEGE - THRISSUR