Hazard
A poison by ingestion and inhalation.
Description
Microcystins are hepatotoxic cyclic heptapeptide toxins produced by cyanobacteria. They are responsible for periodic poisonings of humans and livestock drinking fresh water where the blue-green algae are endemic. Microcystin-LR is a selective inhibitor of protein phosphatase 2A (PP2A) (IC50= 0.04 nM) and will completely inhibit this enzyme without affecting PP1 when used at a concentration of 0.5 nM. The PP1 IC50 is about 1.7 nM. Microcystins are at least 10 times more potent as serine/threonine PP inhibitors than okadaic acid, another microalgal toxin also used for this purpose.
Definition
ChEBI: Microcystin-LR is a microcystin consisting of D-alanyl, L-leucyl, (3S)-3-methyl-D-beta-aspartyl,L-arginyl, 2S,3S,4E,6E,8S,9S)-3-amino-4,5,6,7-tetradehydro-9-methoxy-2,6,8-trimethyl-10-phenyldecanoyl, D-gamma-glutamyl, and 2,3-didehydro-N-methylalanyl residues joined into a 25-membered macrocycle. Produced by the cyanobacterium Microcystis aeruginosa, it is the most studied of the microcystins. It has a role as a bacterial metabolite, an EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor, a xenobiotic and an environmental contaminant.
Safety Profile
A poison by ingestion, inhalation,intraperitoneal, and intravenous route. Experimentalreproductive effects. When heated to decomposition itemits toxic vapors of NOx.
References
1) Rinehart?et al.?(1988),?Nodularin, microcystin, and the configuration of Adda; J. Am. Chem. Soc.,?110?8557
2) Honkanen?et al. (1990),?Characterization of microcystin-LR, a potent inhibitor of type 1 and type 2A protein phosphatases;?J. Biol. Chem,?265?19401
3) Runnegar?et al.?(1995),?Microcystin uptake and inhibition of protein phosphatases: effects of chemoprotectants and self-inhibition in relation to known hepatic transporters; Toxicol. Appl. Pharmacol.,?134?264
