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Thaumatin (also known as talin) is a low-calorie
sweetener A sweetener is a substance added to food or drink to impart the flavor of sweetness, either because it contains a type of sugar, or because it contains a sweet-tasting sugar substitute. Various natural non-sugar sweeteners (NSS) and artificial s ...
and taste modifier. The protein is often used primarily for its flavor-modifying properties and not exclusively as a sweetener. The thaumatins were first found as a mixture of
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s isolated from the
katemfe ''Thaumatococcus daniellii'', also known as miracle fruit or miracle berry, is a plant species from tropical Africa of the Marantaceae (arrowroot & prayer plant) family. It is a large, rhizomatous, flowering herb native to the rainforests of ...
fruit (''
Thaumatococcus daniellii ''Thaumatococcus daniellii'', also known as miracle fruit or miracle berry, is a plant species from tropical Africa of the Marantaceae (arrowroot & prayer plant) family. It is a large, rhizomatous, flowering herb native to the rainforests of w ...
'') (Marantaceae) of
West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...
. Although very sweet, thaumatin's taste is markedly different from sugar's. The
sweetness Sweetness is a basic taste most commonly perceived when eating foods rich in sugars. Sweet tastes are generally regarded as pleasurable. In addition to sugars like sucrose, many other chemical compounds are sweet, including aldehydes, ketones ...
of thaumatin builds very slowly. Perception lasts a long time, leaving a
liquorice Liquorice ( Commonwealth English) or licorice (American English; see spelling differences; ) is the common name of ''Glycyrrhiza glabra'', a flowering plant of the bean family Fabaceae, from the root of which a sweet, aromatic flavouring is ...
-like aftertaste at high concentrations. Thaumatin is highly water soluble, stable to heating, and stable under acidic conditions.


Biological role

Thaumatin production is induced in
katemfe ''Thaumatococcus daniellii'', also known as miracle fruit or miracle berry, is a plant species from tropical Africa of the Marantaceae (arrowroot & prayer plant) family. It is a large, rhizomatous, flowering herb native to the rainforests of ...
in response to an attack upon the plant by
viroid Viroids are small single-stranded, circular RNAs that are infectious pathogens. Unlike viruses, they have no protein coating. All known viroids are inhabitants of angiosperms (flowering plants), and most cause diseases, whose respective eco ...
pathogens. Several members of the thaumatin protein family display significant ''in vitro'' inhibition of
hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...
l growth and sporulation by various
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
. The thaumatin protein is considered a prototype for a pathogen-response protein domain. This thaumatin domain has been found in species as diverse as
rice Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)—or, much l ...
and ''
Caenorhabditis elegans ''Caenorhabditis elegans'' () is a free-living transparent nematode about 1 mm in length that lives in temperate soil environments. It is the type species of its genus. The name is a Hybrid word, blend of the Greek ''caeno-'' (recent), ''r ...
''. Thaumatins are pathogenesis-related (PR) proteins, which are induced by various agents ranging from ethylene to pathogens themselves, and are structurally diverse and ubiquitous in plants: They include thaumatin, osmotin, tobacco major and minor PR proteins, alpha-amylase/trypsin inhibitor, and P21 and PWIR2 soybean and wheat leaf proteins. The proteins are involved in systematically-acquired stress resistance and stress responses in plants, although their precise role is unknown. Thaumatin is an intensely sweet-tasting protein (on a molar basis about 100,000 times as sweet as sucrose) found in the fruit of the West African plant ''Thaumatococcus daniellii'': it is induced by attack by viroids, which are single-stranded unencapsulated RNA molecules that do not code for protein. The thaumatin protein I consists of a single polypeptide chain of 207 residues. Like other PR proteins, thaumatin is predicted to have a mainly beta structure, with a high content of beta-turns and little helix. Tobacco cells exposed to gradually increased salt concentrations develop a greatly increased tolerance to salt, due to the expression of osmotin, a member of the PR protein family. Wheat plants attacked by barley powdery mildew express a PR protein (PWIR2), which results in resistance against that infection. The similarity between this PR protein and other PR proteins and the maize alpha-amylase/
trypsin inhibitor A trypsin inhibitor (TI) is a protein and a type of serine protease inhibitor ( serpin) that reduces the biological activity of trypsin by controlling the activation and catalytic reactions of proteins. Trypsin is an enzyme involved in the breakdow ...
has suggested that PR proteins may act as some form of inhibitor. Within West Africa, the katemfe fruit has been locally cultivated and used to flavour foods and beverages for some time. The fruit's seeds are encased in a membranous sac, or
aril An aril (), also called arillus, is a specialized outgrowth from a seed that partly or completely covers the seed. An arillode, or false aril, is sometimes distinguished: whereas an aril grows from the attachment point of the seed to the ova ...
, that is the source of thaumatin. In the 1970s, Tate and Lyle began extracting thaumatin from the fruit. In 1990, researchers at
Unilever Unilever PLC () is a British multinational consumer packaged goods company headquartered in London, England. It was founded on 2 September 1929 following the merger of Dutch margarine producer Margarine Unie with British soap maker Lever B ...
reported the isolation and sequencing of the two principal proteins found in thaumatin, which they dubbed thaumatin I and thaumatin II. These researchers were also able to express thaumatin in
genetically engineered Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including th ...
bacteria Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
. Thaumatin has been approved as a sweetener in the European Union (E957), Israel, and Japan. In the United States, it is
generally recognized as safe Generally recognized as safe (GRAS) is a United States Food and Drug Administration (FDA) designation that a chemical or substance added to food is considered safe by experts under the conditions of its intended use. An ingredient with a GRAS d ...
as a flavouring agent (FEMA GRAS 3732) but not as a sweetener.


Crystallization

Since thaumatin crystallizes very quickly and easily in the presence of
tartrate A tartrate is a salt or ester of the organic compound tartaric acid, a dicarboxylic acid. The formula of the tartrate dianion is O−OC-CH(OH)-CH(OH)-COO− or C4H4O62−. The main forms of tartrates used commercially are pure crystalline ...
ions, thaumatin-tartrate mixtures are frequently used as model systems to study
protein crystallization Protein crystallization is the process of formation of a regular array of individual protein molecules stabilized by crystal contacts. If the crystal is sufficiently ordered, it will diffract. Some proteins naturally form crystalline arrays, ...
. The solubility of thaumatin, its crystal habit, and mechanism of crystal formation are dependent upon the
chirality Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek (''kheir''), "hand", a familiar chiral object. An object or a system is ''chiral'' if it is distinguishable fro ...
of precipitant used. When crystallized with L- tartrate, thaumatin forms bipyramidal crystals and displays a solubility that increases with temperature; with D- and meso-tartrate, it forms stubby and prismatic crystals and displays a solubility that decreases with temperature. This suggests control of precipitant chirality may be an important factor in protein crystallization in general.


Characteristics

As a food ingredient, thaumatin is considered to be safe for consumption. In a chewing gum production plant, thaumatin has been identified as an allergen. Switching from using powdered thaumatin to liquid thaumatin reduced symptoms among affected workers. Additionally, eliminating contact with powdered gum arabic (a known allergen) resulted in the disappearance of symptoms in all affected workers. Thaumatin interacts with human
TAS1R3 Taste receptor type 1 member 3 is a protein that in humans is encoded by the ''TAS1R3'' gene. The ''TAS1R3'' gene encodes the human homolog of mouse Sac taste receptor, a major determinant of differences between sweet-sensitive and -insensitive m ...
receptor to produce a sweet taste. The interacting residues are specific to old world monkeys and apes (including humans); only these animals can perceive it as sweet.


See also

*
Curculin Curculin or neoculin is a sweet protein complex that was discovered and isolated in 1990 from the fruit of '' Curculigo latifolia'' ( Hypoxidaceae). Like miraculin, curculin exhibits taste-modifying activity; however, unlike miraculin, it also ...
, a sweet protein from Malaysia with taste-modifying activity *
Miraculin Miraculin is a taste modifier, a glycoprotein extracted from the fruit of '' Synsepalum dulcificum''. The berry, also known as the miracle fruit, was documented by explorer Chevalier des Marchais, who searched for many different fruits during ...
, a protein from West Africa with taste-modifying activity *
Monellin Monellin, a sweet protein, was discovered in 1969 in the fruit of the West African shrub known as serendipity berry ('' Dioscoreophyllum cumminsii''); it was first reported as a carbohydrate.GE Inglett, JF May. Serendipity berries - Source of a ...
, a sweet protein found in West Africa *
Stevia Stevia () is a sweet sugar substitute that is about 50 to 300 times sweetness, sweeter than sugar. It is extracted from the leaves of ''Stevia rebaudiana'', a plant native to areas of Paraguay and Brazil. The active compounds in stevia are ...
, a non-nutritive sweetener up to 150 times sweeter than sugar * Lugduname, a sweetening agent up to 300,000 times sweeter than sugar


References


Further reading

* * *


External links

* {{E number infobox 950-969 Sugar substitutes Protein domains Taste modifiers Food additives Plant proteins E-number additives