Crystal structure of an Amadori compound, N-(1-deoxy-β-d-fructopyranos-1-yl)-glycine (“d-fructose-glycine”)

The first crystal structure data on an Amadori compound, N-(1-deoxy-β-d-fructopyranos-1-yl)-glycine, are reported. The space group is P21 with Z = 2 and cell parameters a = 7.246(1), b = 10.009(1), c = 7.060(1) Å, and β = 101.085(6)°. The structure was solved by direct methods and refined to a final R of 2.9% and Rw of 3.8% for 1385 reflections to give esdʹs of 0.002 Å in bond lengths and 0.2° in angles. The conformation of the carbohydrate is the normal 2C5 pyranose chair. Bond lengths and valence angles compare well with average values from a number of pyranose structures. The molecule of the Amadori compound exists in the zwitterion form and has the C-6-O-6-C-2-C-1-N-C-2ʹ-C-1ʹ-O-1ʹ chain in a zig-zag conformation, that is (together with O-2ʹ) substantionally planar. All hydroxyl, carboxyl, and ring oxygen atoms, and the secondary ammonuim group are involved in hydrogen bonding, which forms a three-dimensional network of two infinite chains that have an ammonium group as a common segment. The shortest intra- and inter-molecular hydrogen bonds involve donors of the pyranosyl moiety and acceptors of the amino acid portion, and vice versa.