Citizendia

'Curculin'
Identifiers
SymbolCURC_CURLA
UniProtP19667
Other data

Curculin is a sweet protein that was discovered and isolated in 1990 from the fruit of Curculigo latifolia (Hypoxidaceae),[1] a plant from Malaysia. Swiss-Prot is a manually curated Biological database of Protein sequences Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Hypoxidaceae is the Botanical name of a family of Flowering plants. For the biogeographical region see Malesia Malaysia (məˈleɪʒə or /məˈleɪziə/ is a country that consists of thirteen states and Like miraculin, curculin exhibits taste-modifying activity; however unlike miraculin, it also exhibits a "sweet-taste" by itself. Miraculin is a Glycoprotein extracted from the Miracle fruit plant a shrub native to West Africa ( Synsepalum dulcificum or After consumption of curculin, water and sour solutions taste sweet.

Contents

Protein structure

Curculin is a homodimer consisting of two monomeric units connected through two disulfide bridges. Each mature monomer weighs 12. 5 kDa and consists of a sequence of 114 amino acids. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this 

SIGNAL (22): MAAKFLLTIL VTFAAVASLG MA       1-50: DNVLLSGQTL HADHSLQAGA YTLTIQNKCN LVKYQNGRQI WASNTDRRGS     51-100: GCRLTLLSDG NLVIYDHNNN DVWGSACWGD NGKYALVLQK DGRFVIYGPV    101-114: LWSLGPNGCR RVNGPROPEP (22): GITVAKDSTE PQHEDIKMVI NN

Amino acid sequence of sweet protein curculin adapted from Swiss-Prot biological database of protein sequences. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl [2]

Sweetness properties

Curculin is considered to be a high-intensity sweetener, with a reported relative sweetness of 430-2070 times sweeter than sucrose on a weight basis. [1][3][4]

A sweet taste, equivalent to a 6. 8% or 12% sucrose solution, was observed after holding curculin in the mouth in combination with clear water or acidified water (citric acid), respectively. Solubility of Pure SucroseTemperature(Cg Citric acid is a weak organic Acid. It is a natural Preservative and is also used to add an acidic or sour taste to foods and Soft drinks The sweet taste lasts for 5 minutes with water and 10 minutes with an acidic solution. [1]
Sweetness was also observed with other acids such as ascorbic acid (vitamin C)[5] and acetic acid. This article deals with the molecular aspects of ascorbic acid Vitamin C or L-ascorbate is an Essential nutrient for a large number of higher primate species a small number of other Mammalian Acetic acid, also known as ethanoic acid, is an organic chemical compound, giving Vinegar its sour taste

The taste-modifying activity of curculin is reduced in the presence of ions with two positive charges (such as Ca2+ and Mg2+) in neutral pH solutions, although these ions have no effect in acidic solutions. In the same way, monovalent ions (such as Na+ and Cl-) have no effect in solutions with either neutral or acidic pH. [1][4]

Although the "sweet-inducing" mechanism is unknown, it is believed that one active site of curculin strongly binds to the taste receptor membranes while a second active site fits into the sweet receptor site. A Taste receptor is a type of receptor which facilitates the sensation of Taste. The latter site is thought to be responsible for the induction of sweetness. Presence of Ca2+ and/or Mg2+, water and acids tune the binding of the active site of curculin to the receptor site and therefore modify perceived sweetness. [4]

As a sweetener

Like most proteins, curculin is susceptible to heat. A sweetener is a Food additive which adds the Basic taste of Sweetness to a food artificial sweeteners are Sugar substitutes At a temperature of 50°C the protein starts to degrade and lose its "sweet-tasting" and "taste-modifying" properties, so it is not a good candidate for use in hot or processed foods. However, below this temperature both properties of curculin are unaffected in basic and acidic solutions. [4], so it has potential for use in fresh foods and as a table-top sweetener. A sweetener is a Food additive which adds the Basic taste of Sweetness to a food artificial sweeteners are Sugar substitutes

Because curculin is not widely found in nature, efforts are underway to produce a recombinant form of the protein. In 1997, curculin was expressed in E.coli and yeast, but the recombinant protein did not exhibit "sweet-tasting" or "taste-modifying" activity. Yeasts are a growth form of eukaryotic Microorganisms classified in the kingdom Fungi, with about 1500 Species currently described [6] However, a 2004 study obtained a recombinant curculin, expressed in E.coli, exhibiting "taste-modifying" and "sweet-tasting" properties. [7]

In addition to challenges related to commercial production of the protein, there are many regulatory and legal issues remaining to be resolved before it can be marketed as a sweetener. A sweetener is a Food additive which adds the Basic taste of Sweetness to a food artificial sweeteners are Sugar substitutes Curculin currently has no legal status in European Union and United States. The European Union ( EU) is a political and economic union of twenty-seven member states, located primarily in The United States of America —commonly referred to as the However it is approved in Japan as a harmless additive, according to the List of Existing Food Additives established by the Ministry of Health and Welfare (English publication by JETRO). For a topic outline on this subject see List of basic Japan topics. Food additives are substances added to food to preserve flavour or improve its taste and appearance (ジェトロ　JETRO is an independent government agency established by Japan Export Trade Research Organization as a nonprofit corporation in Osaka on Feb

References

  1. ^ a b c d YYamashita, H., S. Theerasilp, T. Aiuchi, K. Nakaya, Y. Nakamura, and Y. Kurihara. 1990. Purification and complete amino acid sequence of a new type of sweet protein taste-modifying activity, curculin. J. Biol. Chem. 265:15770-15775.
  2. ^ UniProtKB/Swiss-Prot database entry #P19667
  3. ^ Kurihara, Y. 1992. Characteristics of antisweet substances, sweet proteins, and sweetness-inducing proteins. Crit. Rev. Food Sci. Nutr. 32:231-252.
  4. ^ a b c d Yamashita, H., T. Akabane, and Y. Kurihara. 1995. Activity and stability of a new sweet protein with taste-modifying action, curculin. Chem. Senses 20:239-243.
  5. ^ Y Kurihara, H Kohno, M Kato, K Ikeda and M Miyake. Protein curuculin and application of the same. US5242693 A. 1993.
  6. ^ Kurihara, Y. and Nirasawa, S. Structures and activities of sweetness-inducing substances (miraculin, curculin, strogin) and the heat-stable sweet protein, mabinlin. Foods and Food Ingredients Journal of Japan 1997, 67-74.
  7. ^ M Suzuki, E Kurimoto, et. al. Recombinant curculin heterodimer, exhibits taste-modifying and sweet-tasting activities. FEBS Letters 2004, 573, 135-138.

See also

Links

Brazzein is a sweet-tasting Protein extracted from the West African fruit of the climbing plant Oubli ( Pentadiplandra brazzeana Baillon) Miraculin is a Glycoprotein extracted from the Miracle fruit plant a shrub native to West Africa ( Synsepalum dulcificum or Monellin is a sweet Protein which was discovered in 1969 in the fruit of the West African shrub known as Serendipity berry ( Dioscoreophyllum cumminsii Thaumatin is a low-calorie (virtually calorie-free protein sweetener and flavour modifier
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