Microcystins are hepatotoxic cyclic heptapeptide toxins produced by cyanobacteria. They are responsible for periodic poisonings of humans and livestock following consumption of freshwater in areas where the blue-green algae are endemic. The toxicity of microcystins is initiated by the inhibition of the catalytic activity of protein phosphatase (PP) 1 and PP2A. Microcystin-LA differs from the major microcystin variant LR with the substitution of alanine in place of the arginine. It inhibits both PP1C and PP2A with an IC50 value of 0.3 nM.
Microcystin LA from algae has been used as a standard for liquid chromatography/mass spectrometry (LCMS) for toxin analysis.
ChEBI: Microcystin la is a peptide.
Microcystin is a small, monocyclic peptide, composed of seven amino acids connected via peptide bonds. It is a cyanotoxin with hepatotoxic and tumor promoting properties. Several algal genera like Anabaena, Aphanizomenon, Microcystis and Planktothrix produce microcystin. Microcystin has four congeners namely, -LR, -LA, -YR and -RR.
Microcystin LA inhibits protein phosphatase type 2A and protein phosphatase type 3 more potently than protein phosphatase type 1 (order of potency PP2A > PP3 > PP1). Induces neutrophil-activating chemokines and extracellular reactive oxygen species, possible mechanisms of its hepatotoxic effects.
