The anomeric configurations were in all cases determined to be of the form β-D-Manp, with an axial H-1. The value of the 1 JC-1,H-1 scalar coupling constant has been reported to be a reliable indicator of the anomeric configuration , and for D-Manp from groups A, C, and E the measured values for 1 JC-1,H-1 were all ~162 Hz, in contrast to a value of ~170 Hz for an α-configuration (i.e. with an equatorial H-1). The 1 JC-1,H-1 coupling constant could not be determined for the other D-mannosyl groups due to low sensitivity or spectral overlap. The 3 JH-1,H-2 scalar coupling constants could be determined for several of the D-Manp units, and were all ~1 Hz as expected for β-D-Manp-containing oligosaccharides . Spectral overlap prevented determination of the coupling constants for units F and I. Additional confirmations for the β-configuration were obtained from strong NOE observed from H-1 to H-2, H-3, and H-5 protons , for all D-Manp moieties. D-Manp units D and G, which both are the internal unit in a trimannoside, have weaker H-1 to H-3 NOE. 3) GH29, α-fucosidase AlfB Time course of disaccharide formation catalysed by AlfB-WT reveals a peculiar behaviour (Fig. ). Disaccharide formation is slow and once maximal disaccharide yield is reached; it appears to plunge rapidly. Plotting pNP release rate versus donor substrate concentration ([α-L-FucpOCNP]) reveals that this untypical behaviour can be partly explained by the fact that at high (>8 mM) concentration the donor inhibits the WT enzyme (Fig. ) and that at low donor concentration secondary hydrolysis rapidly leads to the decomposition of the disaccharide (Fig. ). In the case of AlfB-H80F, and most other AlfB mutants, substrate inhibition appears to be abolished, and secondary hydrolysis is reduced. NMR spectroscopy was used to assess the transfucosylation capabilities of AlfB forms (see Methods section in the main text). Not all anomeric signals could be followed due to the close vicinity with the HOD peak and its suppression, but signals for the donor, the acceptor and the disaccharide product could be monitored. Particularly, the latter was followed with 4 signals, one for both anomers of the disaccharide, two for its α-anomer and one for the β-anomer (δ = 5.06, 4.93, 4.9 and 4.06 ppm, respectively; Fig. ).