Transglutaminases are able to also cleave the isopeptide bond. This principle is used to provide easy to handle, robust and precise fluorogenic assays suitable for screening of compound libraries and drug development. Further, it reliably detects levels as low as 5% of the physiological amount of FXIIIa (0.05 IU/ml) in plasma (Oertel et al., Anal. Biochem. 2007, 367:152-8).
Mechanism: transglutaminase cleaves the isopeptide bond releasing the dark quencher (2,4-dinitrophenyl) linked to the cadaverine spacer. Subsequently, the increase of fluorescence results from the N-terminally attached fluorophore 2-aminobenzoyl (2-Abz).
Zedira offers two different modified peptides A101
and the related assay kits F001
. The transglutaminase family members discriminate between the peptides as shown in the table.