Thaumatin

Key takeaways

Thaumatin belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Thaumatin to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Thaumatin from memory before moving on to harder problems.

Reference excerpt

Thaumatin (also known as talin) is a low-calorie sweetener 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 proteins isolated from the katemfe fruit (Thaumatococcus daniellii) (Marantaceae) of West Africa. Although very sweet, thaumatin's taste is markedly different from sugar's. The sweetness of thaumatin builds very slowly. Perception lasts a long time, leaving a liquorice-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 in response to an attack upon the plant by viroid pathogens. Several members of the thaumatin protein family display significant in vitro inhibition of hyphal growth and sporulation by various fungi. 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 and Caenorhabditis elegans. 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 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, that is the source of thaumatin. In the 1970s, Tate and Lyle began extracting thaumatin from the fruit. In 1990, researchers at Unilever 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 bacteria. 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 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 ions, thaumatin-tartrate mixtures are frequently used as model systems to study protein crystallization. The solubility of thaumatin, its crystal habit, and mechanism of crystal formation are dependent upon the chirality 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 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, a sweet protein from Malaysia with taste-modifying activity Miraculin, a protein from West Africa with taste-modifying activity Monellin, a sweet protein found in West Africa Stevia, a non-nutritive sweetener up to 150 times sweeter than sugar Lugduname, a sweetening agent up to 300,000 times sweeter than sugar

References

Illustrations

Thaumatin: Thaumatin crystal (~1 mm long) grown by liquid–liquid diffusion under a micro-g environment in outer space. Arrow marks nucleation point.[8] — Thaumatin crystal (~1 mm long) grown by liquid–liquid diffusion under a micro-g environment in outer space. Arrow marks nucleation point.[8]

Worked examples

Example 1 — a first encounter with Thaumatin

Start with the simplest possible case. Write down what Thaumatin claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Thaumatin before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Thaumatin ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Thaumatin

In research: Thaumatin appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Thaumatin in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Thaumatin is common in secondary-school and first-year university syllabi. It links to neighbouring topics E-number additives, Food additives, Plant proteins, so understanding it makes those chapters shorter.
In everyday life: Look for Thaumatin outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Thaumatin in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Thaumatin means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Thaumatin out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Thaumatin in simple terms?

Thaumatin (also known as talin) is a low-calorie sweetener and taste modifier. The protein is often used primarily for its flavor-modifying properties and not exclusively as a sweetener.

Why does Thaumatin matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Thaumatin?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Thaumatin.