- BIOSYNTHESIS OF 1,2,3,6-TETRA-O-GALLOYL-β-D-GLUCOSE
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An enzyme that catalysed the β-glucogallin (1-O-galloyl-β-D-glucose)-dependent galloylation of 1,2,6-tri-O-galloyl-β-D-glucose to 1,2,3,6-tetra-O-galloyl-β-D-glucose was partially purified from leaves of the oak (Quercus robur).This acyltransferase had a Mr of ca 380000, and pH and temperature optima of 6.0 and 55 deg, respectively, and was most stable between pH 4.0 and 6.5.In addition to the natural substrates β-glucogallin (donor) and 1,2,6-trigalloylglucose (acceptor), 1,3,6-trigalloylglucose (which is not an intermediate in the biosynthesis of hydrolysable tannins in oak and sumac) was an equally efficient acceptor molecule; in both cases, 1,2,3,6-tetragalloylglucose was the reaction product.Based on the physiological role of this new enzyme, the systematic name "β-glucogallin: 1,2,6-tri-O-galloyl-β-D-glucose 3-O-galloyltransferase" (EC.2.3.1.-) is proposed. Key Word Index - Quercus robur (Q. pedunculata); Fagaceae; pedunculate oak; Rhus typhina; Anacardiaceae; staghorn sumac; biosynthesis; hydrolysable tannins; galloyltransferase; β-glucogallin; 1,2,6-tri-O-galloyl-β-D-glucose; 1,2,3,6-tetra-O-galloyl-β-D-glucose.
- Hagenah, Sigrid,Gross, Georg G.
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p. 637 - 642
(2007/10/02)
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