AttoTector Microcystins/Nodularins assay is based on the phosphatase activity inhibition by microcystins. Under normal conditions the phophatase is able to hydrolyse a specific substrate that can be detected at 405 nm. Samples containing microcystins or Nodularins will inhibit the enzyme activity proportionally to the amount of toxin contained in the sample. The concentration of the toxin in the sample can be calculated using a standard curve.
The most frequently reported cyanobacterial toxins are the hepatotoxic microcystins (MCs). MCs are peptides with a molecular weight ranging from 900 to 1,100 Da. They consist of seven amino acids of which the two terminal amino acids of the linear peptide are condensed to form a cyclic compound.
Nodularins consist of five amino acids and are closely related to microcystins. Nodularins regularly formed in blooms in the Baltic Sea. Nodularin, like MCs, is a potent inhibitor of eukaryotic-type protein phosphatases 1 and 2A.