Galactinol-sucrose galactosyltransferase () is an enzyme that catalyzes the chemical reaction

The two substrates of this enzyme characterised from the seeds of Vicia faba are galactinol (α-D-galactosyl-(1->3)-1D-myo-inositol) and sucrose. The galactose sugar part of galactinol is transferred to the primary alcohol in the glucopyranose ring of the sucrose, forming the trisaccharide, raffinose, with inositol as a byproduct.

This enzyme belongs to the family of glycosyltransferases, specifically the hexosyltransferases. The systematic name of this enzyme class is alpha-D-galactosyl-(1->3)-myo-inositol:sucrose 6-alpha-D-galactosyltransferase. Other names in common use include 1-alpha-D-galactosyl-myo-inositol:sucrose, and 6-alpha-D-galactosyltransferase. This enzyme participates in galactose metabolism.

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