raffinose

raffinose [′raf·ə‚nōs]

(biochemistry)

C₁₈H₃₂O₁₆·5H₂O A white, crystalline trisaccharide found in sugarbeets, cottonseed meal, and molasses; yields glucose, fructose, and galactose on complete hydrolysis. Also known as gossypose; melitose; melitriose.

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Raffinose

The best-known trisaccharide (oligosaccharide), widely distributed in higher plants. The best-known sources are cottonseed meal and the manna of Eucalyptus. It is also known as melitose, melitriose, gossypose, and O-α- d -galactopyranosyl-(1→6)-O-α- d -glucopyranosyl-(1→2)-β- d -fructofuranoside. See Oligosaccharide

Complete acid hydrolysis gives 1 mole each of d -galactose, d -glucose, and d -fructose. In structure, it comprises melibiose and sucrose with the central d -glucose in common. See Fructose, Galactose, Glucose

Raffinose can be hydrolyzed by enzymes in two ways. Invertase (β- d -fructofuranoside) hydrolyzes the sucrose part of the molecule to give melibiose and d -fructose. Almond emulsin, which contains an α- d -galactosidase, hydrolyzes the melibiose residue to yield d -galactose and sucrose.

Raffinose was found to be enzymically synthesized in plants from uridine diphosphate d -galactose and sucrose by an enzyme which transfers the d -galactose moiety of this sugar nucleotide to sucrose, resulting in the formation of raffinose.