Biochemical Pathways of Heavy Metal Poisoning

2078 Words May 9th, 2013 9 Pages
Biochemical Pathways of Heavy Metals Poisoning
BIO101 (Principles of Biology)
6 July 2012

The biochemical pathways of heavy metal poisoning are routes by which the metals pass in the body as they impair and destroy normal cellular and organ activity. The most common types of heavy metal poisoning are caused by lead, arsenic, cadmium and mercury. They are also the most extensively studied at the moment. Lead poisoning occurs mainly by the inhibitory effect that the metal imposes on enzymes and subsequent distortion of essential biochemical pathways. The metal disrupts calcium metabolism and subsequently causes neurotoxicity. It also inhibits the reduction of glutathionine in a biochemical process meant to produce antioxidants.
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Biochemical Pathways of Lead Poisoning
Disruption of Calcium Metabolism and Neurotoxicity
Lead can activate calmodulin and displace calcium. Therefore, lead can interfere with calmodulin found on the surface of synaptic vesicles hence affecting protein phosphorylation and consequently impairing neurological behavior. This interferes with the roles of calcium in: * Releasing neurotransmitters, * Regulating certain enzymes that limit the rate at which neurotransmitters are synthesized, * The packaging of transmitters within vesicles of presynaptic compartments * Regulation of hormone-dependent cyclases
Enzyme Inhibition in Glutathionine Metabolism Pathway
Lead can be bound to the sulfhydryl groups found on some enzymes.
Normal and functional glutathionine derives its antioxidant properties from the thiol group that occurs in the cystein within it. This group can be readily reduced or oxidized.
Lead (like arsenic and mercury) interferes with glutathionine metabolism by binding to its sulfhydryl complex of the key enzyme involved in this biochemical pathway.
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