Microcystin-LR

Microcystin-LR is a toxin produced by cyanobacteria, specifically the species Microcystis aeruginosa. It is one of the most common and potent forms of microcystin, a class of toxins that can cause serious health problems in humans and animals.

Structure and Properties

Microcystin-LR is a cyclic heptapeptide with a molecular weight of approximately 995 Da. It contains several unusual amino acids, including the non-proteinogenic amino acids Adda and Mdha. The "LR" in its name refers to the two variable L and R groups in its structure, which in this case are Leucine (L) and Arginine (R).

Toxicity

Microcystin-LR is a potent inhibitor of protein phosphatases 1 and 2A, which are essential for many cellular processes in eukaryotes. Inhibition of these enzymes can lead to an overabundance of phosphorylated proteins, disrupting normal cell function and leading to cell death. In humans, exposure to microcystin-LR can cause a range of health problems, from skin irritation and gastrointestinal symptoms to liver damage and potentially cancer.

Exposure and Treatment

Exposure to microcystin-LR can occur through ingestion, inhalation, or skin contact with contaminated water. The toxin is resistant to boiling and many common water treatment methods. However, it can be effectively removed from water using activated carbon or other advanced treatment methods. There is currently no specific antidote for microcystin-LR poisoning, and treatment is primarily supportive.

Environmental Impact

Microcystin-LR is a major concern in water bodies affected by eutrophication, where nutrient-rich conditions can lead to harmful algal blooms of Microcystis aeruginosa and other cyanobacteria. These blooms can release large amounts of microcystin-LR into the water, posing a threat to aquatic life and potentially contaminating drinking water supplies.

See Also

• Cyanotoxin
• Harmful algal bloom
• Water pollution

Microcystin-LR Resources
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