Miraculin

Enhancers and Inducers. A sweetness enhancer is defined as a compound that imparts no taste per se, but when combined with a sweetener in small quantities, increases sweetness intensity. A tme sweetness enhancer has yet to be found. However, a good sweetness inducer, miraculin [143403-94-5] or [125267-18-7] (124), is known. Miraculin is a glycoprotein found in the fmit (called Miracle Fmit) of a West African shmb, chardella dulcifica. By itself, miraculin imparts no sweetness. When activated in the mouth by acidic substances, however, a sucrose-like sweetness is perceived. Thus, sour lemon, lime, grapefmit, rhubarb, and strawberry taste sweet when combined with miraculin. The taste conversion effect can last an hour or longer. 

In 1974, a petition for affiimation of the GRAS status of miracle fmit was submitted by the Miralin Company, mainly based on the fact that miracle fmits have been consumed by humans since before 1958. In 1977, the petition was denied by the FDA. However, miraculin remains a research curiosity. Its stmcture was elucidated in 1989 (125). Another protein, curculin [151404-13-6] (126), has also been reported to exert a sweet-inducing activity similar to miraculin. 

That the initial event of taste stimulation takes place on the cell surface of the taste receptor is now universally accepted. In addition, accumulated evidence strongly suggests that taste-bud stimulation is extracellular in nature. For example, (1) the sweet-taste response is both rapid and reversible, (2) the intensely sweet proteins monellin" and thaumatin could not possibly penetrate the cell, because of their size, and (3) miraculin, the taste-modifying glycoprotein, having a molecular weight of 44,000 would also be too large to penetrate the taste cell. ... 

The design of safe sweeteners is very important for people who are afiected by diabetes, hyperlipemia, caries and other diseases that are linked to sugar consumption. Sweet proteins, which are found in several tropical plants, are many times (100-100,000) sweeter than sucrose on a molar basis. Only a few sweet proteins are known miraculin, monellin, thaumatin, curculin, mabinlin. 

Most sweet compounds including the commercial sweeteners, are small molecular weight compounds but there are also sweet macromolecules both synthetic and natural. It was thought that compounds with molecular masses over 2 500 would generally be tasteless. It was assumed that macromolecules such as proteins could elicit a sweet taste similar to small molecules such as sucrose and stevioside until the discovery of miraculin. 

There are seven known sweet and taste-modifying proteins, namely (1) monellin and (2) thaumatin (3) mabinlin. and (4) curculin (5) pentadin, (6) brazzein and (7) miraculin.The properties and characteristics of these proteins are illustrated in Table 2. There are several recent reviews relating to sweet proteins. Apart from curculin and... 

Table 2. Comparison of Thaumatin, Monellin, Mabinlin, Pentadin, Brazzein, Curculin and Miraculin... 

Thaumatin Monellin Mabinlin Pentadin Brazzein Curculin Miraculin... 

Because of this unusual property, the berry has been called miracle fruit. Kurihara and Beidler first isolated the active principle of the miracle fruit and showed that it is a basic glycoprotein. Brouwer and his colleagues also isolated the active principle and named it miraculin . 

Miraculin is a glycoprotein which not only shields a sour taste, it can also make you believe that what you are eating or drinking is actually sweet It is a 190 amino acid glycoprotein and its amino acid sequence was determined completely by Theerasilip and his Japanese colleagues.Miraculin... 

The detailed mechanism of its taste-inducing behavior is still unknown. It has been suggested that the miraculin molecule can change the structure of taste cells on the tongue. As a result, the sweet receptors are activated by acids, which are sour in general. This effect remains until the taste buds return to normal. 

Takahashi N, Hitotsuya H, Hanzawa H, Arata Y, Kurihara Y, Structural study of asparagine-linked oligosaccharide moiety of taste-modifying protein, miraculin,... 

Unusual proteins are also characteristic of the biome free-sulfydryl type for both tropical Americas and the East, and taste-modifying type, like miraculin, monellins, and thaumatin, for tropical Africa. 

Sweetening agents miraculin/ca. 44,000 MW glycoprotein red berries of Synsepcdum dulciflcum (Schum.) Daniell, Sapotaceae, Ang. from W Africa. 

The proteins miraculin and circulin from tropical fruits modify taste. Acids taste sweet rather than sour after the tongue has been treated with either protein.945 946 Exposure of the tongue to artichokes often... 

Lycopersicon esculentum (tomato) (Solanaceae) Lycopersicon Miiaculin-like protein (LeMir) (181 aa 20 kDa 6 Cys 3 S-S) STI (Kunitz) Miraculin homologue (Miraculin converts sour taste to sweet) [384]... 

Richadella dulcifica (miracle fruit) (Sapotaceae) [fruit] Miraculin (MIR) (25 kDa glycoprotein 220 aa 24 kDa 7 Cys 3 S-S 1 interchain S-S) Soybean KPI homologue (converts sour to sweet taste) [416- 420]... 

A cDNA clone encoding miraculin was isolated and sequenced. The encoded precursor of miraculin was composed of 220 amino acid residues, including a possible signal sequence of 29 amino acids.95 96 Attempts have been made to express these proteins in E. coli, yeast, and tobacco. While it was confirmed that these proteins were expressed in these organisms, miraculin expressed in E. coli and yeast showed no activity.97 The perception of 0.1 moll-1 of citrate after taking 1 pmoll-1 of miraculin corresponds to the sweetness of 0.4 mol l-1 of sucrose, which means that it is 400 000 times sweeter than sucrose on a molar basis. Interestingly, a mixture of miraculin with citrate did not elicit sweetness.97 Miraculin was denied approval for this purpose by the FDA. Miraculin also has no legal status in the European Union. 

Miraculin Synsepalum dulcificum (miracle fruit) Glycoprotein that... 

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