tannase | |||||||||
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Identifiers | |||||||||
EC no. | 3.1.1.20 | ||||||||
CAS no. | 9025-71-2 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
Gene Ontology | AmiGO / QuickGO | ||||||||
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The enzyme tannase (EC 3.1.1.20) catalyzes the following reaction: [1]
It is a key enzyme in the degradation of gallotannins and ellagicitannins, two types of hydrolysable tannins. [2] Specifically, tannase catalyzes the hydrolysis of ester and depside bonds of hydrolysable tannins to release glucose and gallic or ellagic acid. [3] [2]
Tannase belongs to the family of hydrolases, specifically those acting on carboxylic ester bonds. The systematic name is tannin acylhydrolase. Other names in common use include tannase S, and tannin acetylhydrolase. [4]
This enzyme has two known domains and one known active site. [3] Tannase can be found in plants, bacteria, and fungi and has different purposes depending on the organism it is found in. [2] Tannase also has many purposes for human use. The production of gallic acid is important in the pharmaceutical industry as it's needed to create trimethoprim, an antibacterial drug. [5] Tannase also has many applications in the food and beverage industry. Specifically, its used to make food and drinks taste better, either by removing turbidity from juices or wines, or removing the bitter taste of tannins in some food and drinks, such as acorn wine. [3] Additionally, because tannase can break ester bonds of glucose with various acids (chebulinic, gallic, and hexahydrophenic), it can be used in the process of fruit ripening. [6]
In addition to catalyzing the hydrolysis of the central ester bond between the two aromatic rings of digallate (depsidase activity), tannase may also have an esterase activity (hydrolysis of terminal ester functional groups that are attached to only one of the two aromatic rings). [4]
Digallate is the conjugate base of digallic acid, [7] but are often used synonymously. Similarly, gallate and gallic acid are used interchangeably. [8] Both digallic and gallic acid are organic acids that are seen in gallotannins and are usually esterified to a glucose molecule. [2] In other words, tannins (which contain digallate/digallic acid) are the natural substrate of tannase. When tannins, specifically gallotannins, are broken down by tannase through the hydrolysis of ester bonds, gallic acid and glucose are formed. [2]
The crystal structure of tannase varies slightly depending on the strain being observed, in this case we are looking at the tannase SN35N strain produced in Lactobacillus plantarum. On average, its molecular weight is in the range of 50-320 kDa. [3]
Tannase from Lactobacillus plantarum has 489 amino acid residues and two domains. [5] The two domains of tannase are called the α/β-hydrolase domain and the lid domain. The α/β-hydrolase domain consists of residues 4-204 and 396-469, and is composed of two nine-stranded β-sheets surrounded by four α-helices on one side and two α-helices on the other side. Conversely, the lid domain consists of residues 205–395 and is composed of seven α-helices and two β-sheets. [3]
There is one known active site in tannase found in the SN35N strain. The crystal structure shows there is a tunnel formed by two opposing domains that can fit the various substrates needed for tannase to hydrolyze. [3] This active site is referred to as the Ser163 active site and is located in the α/β-hydrolase domain. In this active site Ser163, Asp419, and His451 residues form a catalytic triad. [3] [6] If any one of these residues are mutated in the catalytic triad, tannase activity almost always stops. [9]
One way in which the structure of tannase is tied with its function involves a loop structure, called the flap. The flap connects β8 and β9 sheets and is located under the catalytic triad. As a result of weak electron densities, this structure is very flexible. Due to its flexibility, the flap is better able to guide the substrate in entering the enzyme and helps to strengthen the overall binding of the complex by forming additional interactions with other parts of the substrate. [9]
Tannase functions differently in the cell depending on the organism being observed. In many plants, tannase is used to produce tannins, which are found in leaves, wood, and bark. [10] The production of tannins in plants is essential for defense against herbivory, as they cause a strong unpalatable flavor. [11] Tannins are considered secondary metabolites in plants. Therefore, their production by tannase plays no direct role in plant primary metabolism.[ citation needed ]
On the other hand, tannase serves a different purpose in many microorganisms. In the cell, tannase is a key enzyme in the degradation of gallotannins . [12] This is important, because some microorganisms use tannase to breakdown hydrolysable tannins, such as gallotannins, to form glucose and gallic acid. [5] [13] These byproducts are created from the hydroxylation of the aromatic nucleus of the tannin, followed by ring cleavage. Glucose and gallic acid can then be readily converted to metabolites (i.e. pyruvate, succinate, and acetyl coenzyme A) that can be used in the Krebs cycle. Specific microorganisms that utilize tannase in this way include Pseudomonas species. [14]
Tannase is present in a diverse group of microorganisms, including rumen bacteria. [12] Many other bacterial species have been found to produce tannase by being isolated from different types of media such as soil, wastewater, compost, forest litter, feces, beverages, pickles, etc. Bacteria and archaea species with tannase activity have been found in the genera: Achromobacter, Atopobium, Azotobacter, Bacillus, Citrobacter, Corynebacterium, Enterobacter, Enterococcus, Fusobacterium, Gluconoacetobacter, Klebsiella, Lactobacillus, Lonepinella, Methanobrevibacter, Microbacterium, Oenococcus, Pantoea, Pediococcus, Providencia, Pseudomonas, Selenomonad, and Serratia. [15] In addition, some fungal species are dominant tannase producers, such as Aspergilli species. [2]
β-Galactosidase is a glycoside hydrolase enzyme that catalyzes hydrolysis of terminal non-reducing β-D-galactose residues in β-D-galactosides.
Cellulase is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides:
Aspartate transaminase (AST) or aspartate aminotransferase, also known as AspAT/ASAT/AAT or (serum) glutamic oxaloacetic transaminase, is a pyridoxal phosphate (PLP)-dependent transaminase enzyme that was first described by Arthur Karmen and colleagues in 1954. AST catalyzes the reversible transfer of an α-amino group between aspartate and glutamate and, as such, is an important enzyme in amino acid metabolism. AST is found in the liver, heart, skeletal muscle, kidneys, brain, red blood cells and gall bladder. Serum AST level, serum ALT level, and their ratio are commonly measured clinically as biomarkers for liver health. The tests are part of blood panels.
DD-transpeptidase is a bacterial enzyme that catalyzes the transfer of the R-L-αα-D-alanyl moiety of R-L-αα-D-alanyl-D-alanine carbonyl donors to the γ-OH of their active-site serine and from this to a final acceptor. It is involved in bacterial cell wall biosynthesis, namely, the transpeptidation that crosslinks the peptide side chains of peptidoglycan strands.
Exo-α-sialidase is a glycoside hydrolase that cleaves the glycosidic linkages of neuraminic acids:
The enzyme glucose 6-phosphatase (EC 3.1.3.9, G6Pase; systematic name D-glucose-6-phosphate phosphohydrolase) catalyzes the hydrolysis of glucose 6-phosphate, resulting in the creation of a phosphate group and free glucose:
β-Glucocerebrosidase is an enzyme with glucosylceramidase activity that cleaves by hydrolysis the β-glycosidic linkage of the chemical glucocerebroside, an intermediate in glycolipid metabolism that is abundant in cell membranes. It is localized in the lysosome, where it remains associated with the lysosomal membrane. β-Glucocerebrosidase is 497 amino acids in length and has a molecular mass of 59,700 Da.
β-Glucosidase is an enzyme that catalyses the following reaction:
6-Phosphogluconolactonase (EC 3.1.1.31, 6PGL, PGLS, systematic name 6-phospho-D-glucono-1,5-lactone lactonohydrolase) is a cytosolic enzyme found in all organisms that catalyzes the hydrolysis of 6-phosphogluconolactone to 6-phosphogluconic acid in the oxidative phase of the pentose phosphate pathway:
α-Amylase is an enzyme that hydrolyses α bonds of large, α-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose, through the following biochemical process:
In enzymology, a limonene-1,2-epoxide hydrolase (EC 3.3.2.8) is an enzyme that catalyzes the chemical reaction
In enzymology, a microsomal epoxide hydrolase (mEH) is an enzyme that catalyzes the hydrolysis reaction between an epoxide and water to form a diol.
The enzyme polyneuridine-aldehyde esterase (EC 3.1.1.78) catalyzes the following reaction:
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.
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.
A hydrolysable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids.
The ellagitannins are a diverse class of hydrolyzable tannins, a type of polyphenol formed primarily from the oxidative linkage of galloyl groups in 1,2,3,4,6-pentagalloyl glucose. Ellagitannins differ from gallotannins, in that their galloyl groups are linked through C-C bonds, whereas the galloyl groups in gallotannins are linked by depside bonds.
Glucogallin is chemical compound formed from gallic acid and β-D-glucose. It can be found in oaks species like the North American white oak, European red oak and Amla fruit.
Glucanases are enzymes that break down large polysaccharides via hydrolysis. The product of the hydrolysis reaction is called a glucan, a linear polysaccharide made of up to 1200 glucose monomers, held together with glycosidic bonds. Glucans are abundant in the endosperm cell walls of cereals such as barley, rye, sorghum, rice, and wheat. Glucanases are also referred to as lichenases, hydrolases, glycosidases, glycosyl hydrolases, and/or laminarinases. Many types of glucanases share similar amino acid sequences but vastly different substrates. Of the known endo-glucanases, 1,3-1,4-β-glucanase is considered the most active.
N-acetyl-β-d-glucosaminidase(EC 3.2.1.30; EC 3.2.1.52) is a mesophilic hydrolase that specifically hydrolyzes N-acetyl-glucosides. The enzyme is found across a wide variety of marine and terrestrial creatures with the primary function of breaking down oligosaccharides in the presence of water. One of the primary functions of the enzyme is to target and hydrolyze oligosaccharides containing chitin. In this chitinase function, the enzyme contributes to the ability of many organisms to break down chitin-containing molecules and subsequently digest or re-uptake environmental chitin, carbon, or nitrogen. The enzyme's crystal structure varies slightly across organisms, but is characterized by three or four domains with one active site. Across proteins, the active site entails an α-β barrel with either an arginine or tryptophan residues in the barrel pocket to bind incoming substrate.