Fig. 6

Subsite specificities and preferences of CSN, CSN-Y270A, CSN-E59A, and CSN-W118A on chitosan polymer DA 30%. The enzymes were incubated at 37 °C with 1 mg/ml chitosan polymer DA 30% until the endpoint (60 h in total). CSN, CSN-Y270A, CSN-E59A, and CSN-W118A were used at concentrations of 0.05 μM, 0.3 μM, 0.05 μM, and 2.5 μM, respectively. The frequencies of GlcN and GlcNAc units occurring at and near the reducing and non-reducing ends of the oligomers produced were determined using quantitative mass spectrometric sequencing. The mean values for the GlcN frequencies at the subsites (− 3) to (+ 3) are indicated. The experiments were performed as triplicates with one batch of each enzyme