Arsenic poisoning kills by allosteric inhibition of essential metabolic enzymes, leaing to death from multi-system organ failure. It primarily inhibits enzymes that require lipoic acid as a cofactor, such as pyruvate and alpha-ketoglutarate dehydrogenase. Because of this, substrates before the dehydrogenase steps accumulate, such as pyruvate (and lactate). It particularly affects the brain, causing neurological disturbances and death.