Non-commercially available enzymes were expressed according to previous literature (Karwaski et al., 2002 (link); Moremen et al., 2018 (link); Prudden et al., 2017 (link)). The amount of enzyme that was added to the reactions is given in units (u, enzyme) per μmol (substrate) for commercial enzymes and μg (enzyme) per μmol (substrate) for in-house expressed enzymes. One unit of the commercially available enzymes is defined as the amount of enzyme that catalyzes the conversion of 1 μmol substrate per minute using the conditions provided by the supplier. Final reactants were purified with a size exclusion Biogel (P2) from BioRad in an Econo glass column (0.7 × 30 cm / 1.5 × 30 cm / 1.5 × 50 cm) and a BioFrac fraction collector from BioRad. The carbohydrate-containing fractions were visualized using thin layer chromatography and an appropriate staining reagent (15 mL AcOH and 3.5 mL p-Anisaldehyde in a mixture of 350 mL EtOH and 50 mL H2SO4), followed by heating.
The starting material for the enzymatic synthesis was obtained from egg yolk extraction as described by Seko et al. and further optimized by others (Liu et al., 2017 (link); Seko et al., 1997 (link); Sun et al., 2014 (link); Zou et al., 2012 ).
The starting material for the enzymatic synthesis was obtained from egg yolk extraction as described by Seko et al. and further optimized by others (Liu et al., 2017 (link); Seko et al., 1997 (link); Sun et al., 2014 (link); Zou et al., 2012 ).