Reaction: α-D-galactosyl-(1→3)-1D-myo-inositol + raffinose = myo-inositol + stachyose
For diagram of reaction click here.
Glossary: raffinose = β-D-fructofuranosyl α-D-galactopyranosyl-(1→6)-α-D-glucopyranoside
Other name(s): galactinol-raffinose galactosyltransferase; stachyose synthetase; α-D-galactosyl-(1→3)-myo-inositol:raffinose galactosyltransferase
Systematic name: α-D-galactosyl-(1→3)-1D-myo-inositol:raffinose galactosyltransferase
Comments: This enzyme also catalyses galactosyl transfer from stachyose to raffinose (shown by labelling) [4]. For synthesis of the substrate, see EC 2.4.1.123, inositol 3-α-galactosyltransferase. See also EC 2.4.1.82, galactinol—sucrose galactosyltransferase.
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 37277-70-6
References:
1. Tanner, W. Die Biosynthese der Stachyose. Ber. Dtsch. Bot. Ges. 80 (1967) 111 only.
2. Tanner, W. and Kandler, O. Myo-inositol, a cofactor in the biosynthesis of stachyose. Eur. J. Biochem. 4 (1968) 233-239. [PMID: 5655499]
3. Lehle, L. and Tanner, W. The function of myo-inositol in the biosynthesis of raffinose. Purification and characterization of galactinol:sucrose 6-galactosyltransferase from Vicia faba seeds. Eur. J. Biochem. 38 (1973) 103-110. [PMID: 4774118]
4. Kandler, O. and Hopf, H. Occurrence, metabolism and function of oligosaccharides. In: Preiss, J. (Ed.), The Biochemistry of Plant vol. 3, Academic Press, New York, 1980, pp. 221-270.