 Glucose exists predominantly as a mixture of α and β "pyranose" isomers, but only the α form links to fructose.Fructose itself exists as a mixture of α and β "furanose" isomers, but only the β isomer links to glucose.Unlike most disaccharides, the glycosidic bond in sucrose is formed between the reducing ends of both glucose and fructose, and not between the reducing end of one and the non-reducing end of the other.