pyr + NAD + CoASH <---> acetyl-CoA + NADH

     Pyruvate dehydrogenase contains a coenzyme, lipoic acid (green balls in figure), that helps complete the reaction, yet easily binds arsenic as AsO2, inhibiting the enzyme.  Less acetyl-CoA means less Krebs cycle, and thus less total ATP per glucose oxidized.

     Low levels of arsenic are used to kill molds on many crops; high doses can kill humans. Chronic arsenic poisoning causes sores on the skin, especially the feet. Arsenic can leak from the soil into drinking water wells; In India such contamination of water wells has exposed 75 millions people to toxic levels of arsenic.

Pyruvate Dehydrogenase