A gallotannin is a class of molecules belonging to the hydrolysable tannin

Hydrolysable tannin

A hydrolyzable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids....

s. Gallotannins are polymers formed when gallic acid

Gallic acid

Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, a type of organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula is C6H23COOH. Gallic acid is found both free and as part of...

, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol

Polyol

A polyol is an alcohol containing multiple hydroxyl groups. In two technological disciplines the term "polyol" has a special meaning: food science and polymer chemistry.- Polyols in food science :...

 carbohydrate such as glucose.

Metabolism

Gallate 1-beta-glucosyltransferase

Gallate 1-beta-glucosyltransferase

In enzymology, a gallate 1-beta-glucosyltransferase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are UDP-glucose and gallate, whereas its two products are UDP and 1-galloyl-beta-D-glucose....

 uses UDP-glucose and gallate

Gallic acid

Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, a type of organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula is C6H23COOH. Gallic acid is found both free and as part of...

  to produce UDP

Uridine diphosphate

Uridine diphosphate, abbreviated UDP, is a nucleoside diphosphate. It is an ester of pyrophosphoric acid with the nucleoside uridine. UDP consists of the pyrophosphate group, the pentose sugar ribose, and the nucleobase uracil.-See also:* Nucleoside...

 and 1-galloyl-beta-D-glucose.
Beta-glucogallin O-galloyltransferase

Beta-glucogallin O-galloyltransferase

In enzymology, a beta-glucogallin O-galloyltransferase is an enzyme that catalyzes the chemical reactionHence, this enzyme has one substrate, 1-O-galloyl-beta-D-glucose, and two products, D-glucose and 1-O,6-O-digalloyl-beta-D-glucose....

 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

Beta-glucogallin-tetrakisgalloylglucose O-galloyltransferase

In enzymology, a beta-glucogallin-tetrakisgalloylglucose O-galloyltransferase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are 1-O-galloyl-beta-D-glucose and 1,2,3,6-tetrakis-O-galloyl-beta-D-glucose, whereas its two products are D-glucose and...

 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).

Tannase

Tannase

In enzymology, a tannase is an enzyme that catalyzes the chemical reactionThus, the two substrates of this enzyme are digallate and H2O, whereas its product is gallate....

 is a key enzyme in tha degradation of gallotannins that uses digallic acid

Digallic acid

Digallic acid is a polyphenolic compound found in Pistacia lentiscus. Digallic acid is also present in the molecule of tannic acid. Digalloyl esters involve either -meta or -para depside bonds....

 and H₂O to produce gallic acid

Gallic acid

Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, a type of organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula is C6H23COOH. Gallic acid is found both free and as part of...

.