Scheme 1
Schematic diagram of the GOOX-based HRP colorimetric method for assaying AA9 LPMO activity. The action of the C1-type LPMO towards PASC releases native oligosaccharides and aldonic oligosaccharide derivatives, with only native oligosaccharides having a reducing aldehyde end. The action of the C4-type LPMO releases native oligosaccharides and gemdiol oligosaccharide derivates, with both products having a reducing aldehyde end. The native oligosaccharides released by C1 LPMO cleavage and the two products released by C4 LPMO cleavage are then oxidized by GOOX, generating a stoichiometric amount of H2O2, which is finally quantified by the HRP colorimetric assay. RE: reducing aldehyde end in oligosaccharides