The CfMan2A-N428T reaction mixture contained the substrate β-D-ManpOpNP, transglycosylation products (Fig. ) and D-mannose that results from hydrolysis of the substrate. Identification of the transglycosylation products was performed using 1 H-and C-NMR spectroscopy. The 1D 1 H spectrum of the sample revealed the presence of ten anomeric resonances, corresponding to ten D- Manp moieties (labelled A-I). Three of the D-Man units could be identified as α-D-Manp, β-D-Manp, and β-D-Manp B OpNP, i.e. D-Manp unit B, from comparisons to 1 H-and C-NMR spectra of the substrate β-D-ManpOpNP (NMR data acquired in-house), or using the NMR chemical shift database BioMagResBank 1 , for α-, and β-D-Manp residues. Each of the spin systems with the remaining anomeric resonances were identified, and virtually complete 1 H and C resonance assignments of the corresponding D-Manp residues were obtained (Table ). The chemical shifts of the 1 H anomeric (H-1) resonances are consistent with expected chemical shifts for substituted β-D-Manp units .