Gallotannin
A gallotannin is any of a class of molecules belonging to the hydrolysable tannins. Gallotannins are polymers formed when gallic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose.
Metabolism
Gallate 1-beta-glucosyltransferase uses UDP-glucose and gallate to produce UDP and 1-galloyl-beta-D-glucose. Beta-glucogallin O-galloyltransferase uses 1-O-galloyl-beta-D-glucose to produce D-glucose and 1-O,6-O-digalloyl-beta-D-glucose. Beta-glucogallin-tetrakisgalloylglucose O-galloyltransferase uses 1-O-galloyl-beta-D-glucose and 1,2,3,6-tetrakis-O-galloyl-beta-D-glucose to produce D-glucose and 1,2,3,4,6-pentakis-O-galloyl-beta-D-glucose (1,2,3,4,6-penta-O-galloyl-β-D-glucose, the common precursor of gallotannins and the related ellagitannins).[1]
Tannase is a key enzyme in the degradation of gallotannins that uses digallic acid and H2O to produce gallic acid.
See also
References
- ^ Cammann, Jessica; Denzel, Klaus; Schilling, Gerhard; Gross, Georg G. (August 1989). "Biosynthesis of gallotannins: β-Glucogallin-dependent formation of 1,2,3,4,6-pentagalloylglucose by enzymatic galloylation of 1,2,3,6-tetragalloylglucose". Archives of Biochemistry and Biophysics. 273 (1): 58–63. doi:10.1016/0003-9861(89)90161-6. PMID 2757399.
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Digalloyl glucoses: |
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Trigalloyl glucoses: |
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Tetragalloyl glucoses: |
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Pentagalloyl glucose: |
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other |
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Galloyl quinic acids: |
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Digalloyl quinic acids: |
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Trigalloyl quinic acids: |
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- 4-O-Galloyl shikimic acid
- 5-O-Galloyl shikimic acid
- 3,5-di-O-galloyl-shikimic acid
- 3,4,5-tri-O-galloylshikimic acid
- 1,2,6-trigalloyl alloside
- 1,3,6-trigalloyl alloside
- 1,2,3,6-tetragalloyl alloside
- 1-O-galloyl proto-quercitol
- 1,4-di-O-galloyl proto-quercitol