<prompt> Which of the following enzyme is affected by cyanide poisoning?G-6-P dehydrogenase deficiencyIsomeraseCytochrome oxidaseNone of the above  <response>: Cyanide is a chemical asphyxiant; binding to cellular cytochrome oxidase, it blocks the aerobic utilization of oxygen. Unbound cyanide is detoxified by metabolism to thiocyanate, a much less toxic compound that is excreted in the urine. Ref: Blanc P.D. 2012. Chapter 57. Cyanide. In K.R. Olson Ed, Poisoning Drug Overdose, 6e. 