Provide an explanation for why the toxicity of mercury is gr

Provide an explanation for why the toxicity of mercury is greatly increased by the action of enzymes containing cobalamin.

Solution

Inside human body, the inactive form of vitamin B12 ( like cyanocobalamin) gets converted to activated form of methyl cobalamin.

This methylcobalamin increases the toxicity of mercury, by modyfying the less toxic inorganic form of mercury, i.e. Hg2+, into the highly toxic organic form of methyl mercury (CH3Mg).

it can modify the less toxic inorganic mercury (Hg2+) into the high toxic organic methyl mercury (MeHg) due to giving its methyl group.

This methyl mercury the entero-hepatic cycle in the body through saliva and gets reabsorbed. Thus its toxicity is greatly increased.