These results suggested that our expected product was too reactive to be isolated and was immediately attacked by methanol that was used as solvent for hydrogenolysis, giving rise to the corresponding [alpha]-glycoside with inversion of configuration at the anomeric carbon atom.
Glycosidic bond formation is achieved by a chemical reaction between the anomeric carbon atom (C1) of one monosaccharide molecule and a hydroxy group of another monosaccharide molecule, and results in an oxygen bridge between the two molecules.
The hydroxy group at the anomeric carbon atom of, for example, D-glucose can point either downward or upward, giving rise to the a and [beta]-isomers of D-glucose, respectively.
However, to achieve an efficient enzymatic glycosylation, it is absolutely important to introduce an appropriate leaving group on the anomeric carbon atom.
Also, considering the nature of the chemistry of the PAE resin (an amino functional polymer) and that the relaxation rates of the carbonyl carbons at 173 ppm and the carbohydrate anomeric carbon at 105 ppm are significantly increased, it is reasonable to assume that the PAE resin is interacting with these soy flour components, most likely via secondary interactions.
The peaks are assigned as follows: 173 ppm to the amino acid carbonyls, 105 ppm to the C-1 anomeric carbons of the carbohydrate, 73 ppm to the carbohydrate CHs having secondary hydroxyls, 60 ppm to the C[H.