Protein sweet

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. ... 

In a study of the three-dimensional structure of thaumatin, it was reported that, not only do antibodies raised against thaumatin cross-react with monellin,but antibodies raised against monellin also cross-react with thaumatin, suggesting that there is some structural similarity between portions of the two sweet-protein molecules. Earlier studies " had shown that there is a limited homology in the amino acid sequence in the two proteins. Five tripeptides in monellin have their counterparts in thaumatin. 

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. 

Brazzein is another small sweet-tasting protein whose solution structure has been recently solved by NMR. Brazzein tastes 2000 times sweeter than sucrose on a weight basis and is exceptionally thermostable. As indicated by NMR, the structure of this 54 residue, single-chain polypeptide does not change between 32 and 82 °C and retains its sweetness after incubation at 98 °C for two hours.Brazzein contains one a-helix and three strands of antiparallel jd-sheet stabilized by four intramolecular disulphide bonds. It has been proposed that the disulphide bonds could be responsible for the thermostability of brazzein by forming a compact structure at the tertiary level.The structure of brazzein does not resemble that of the other two sweet proteins with known structures, monellin and thaumatin, whereas sequence alignment and structural prediction indicate that brazzein shares the fold of a newly identified family of serine proteinase inhibitors. 

The continuing search for sweeteners that will reduce obesity, is now focused on natural sweeteners derived from plants and most of those discovered are many times sweeter than sugar. Two classes of such sweeteners are certain sweet glycosides and sweet proteins. 

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... 

Mabinlin, the other known sweet proteins were discovered in West Africa (Table 2). 

Pentadin is a sweet protein extracted from the plant, Pentadiplandra brazzeana Baillon, a shrub found in tropical forests of a few African... 

Liu X, Maeda S, Hu Z, Aiuchi T, Nakaya K, Kurihara Y, Purification, complete amino acid sequence and structural characterization of the heat stable sweet protein, marbinlin II, Eur J Biochem 211 281-287, 1993. 

Hu Z, He M, Studies on mabinlin, a sweet protein from the seeds of Capparis masaikai levl. L. extraction, purification and certain characteristics, Acta Botan Yunnan, 5 207-212, 1983. 

Ming D, Hellekant G, Brazzein, a new high potency thermostable sweet protein from Pentadiplandra Brazzeana B, EEBS Lett, 355 106-108, 1994. 

Kant R, Sweet proteins — Potential replacement for artificial low calorie sweet-ners. Nutrition Journal 4 5, 2005. 

Kurihara Y, Harada S, Maeda S, Kai Y, Kasai N, GrystaUization and preliminary X-ray diffraction studies of curcidin A new type of sweet protein having taste-modifying action,/Afo/Sio/238 286—287, 1994. 

Nirasawa S, Nishino T, Katahira M, Uesugi S, Hu Z, Kurihara Y, Structures of heat-stable and unstable homologues of the sweet protein mabinlin, Eur J Biochem 223 989—995, 1994. 

Yamashita H,Theerasilp S, AiuchiT, NakayaK, Nakamura Y, Kurihara Y, Purification and complete amino acid sequence of a new type of sweet protein with taste-modifying activity, curculin, / o/ Chem 265(26) 15770-15775, 1990. 

Kondo, K., Miura, Y., Sone, H., Kobayashi, K., and lijima, H (1997). High-level expression of a sweet protein, moneUin, in the food yeast Candida utilis. Nature Biotechnol. 15,453. 

NT523 Cusack, M. and W. S. Pierpoint. Similarities between sweet protein thauma-tin and A pathogenesis-related protein from tobacco. Phytochemistry 1988 27(12) 3817-3821. 

A Mackenzie, JB Pridham, NA Saunders. Changes in the sweet proteins (thaumatins) in Thaumato-coccus danielli fruits during development. Phytochem 24(11) 2503-2506, 1985. 

Pierpoint, W., Tatham, A. Pappin, D. (1987). Identification of the virus-induced protein of tobacco leaves that resembles the sweet-protein thaumatin. Physiological and Molecular Plant Pathology 31, 291-8. 

The occurrence of sweet-tasting proteins, such as thaumatin, monellin, mabinlin and pentadin, in the pulp of fruits of various rain forest species has been reported. The sweet-tasting proteins have different molecular lengths (from 54 residues of brazzein to 207 residues of thaumatin), virtually no sequence homology and very little structural homology. Thaumatin, the most characterised sweet protein, is 100,000 times sweeter than sugar on a molar... 

Temussi, P.A. 2002. Why are sweet proteins sweet Interactions of brazzein, menellin and thaumatin with the T1R2-T1R3 receptor. FEBS Lett. 526, 1-4. 

Morini, G., Bassoli, A., Temussi, P.A. (2005) From small sweeteners to sweet proteins anatomy of the binding sites of the human... 

Monellin is a sweet protein that was isolated from the fruit of Dioscoreophyllum cumminsii (Staff Diels, which is known as the serendipity berry and is native to West Africa. It is a basic protein with an isoelectric point of approximately 9.3 and is 3000 times sweeter than sucrose.65 66 Perception lasts for more than 1 h and leaves an aftertaste. Heat denatures monellin proteins they lose their sweetness when heated over 50 °C at low pH. Monellin has a molecular mass of 10.7 kDa. Monellin has two noncovalently associated polypeptide chains chain A contains 44 amino acid residues and chain B has 50 residues. In 1976, the primary structure of monellin was proposed independently by three groups but their results all differed somewhat.67-69... 

Brazzein is a sweet protein that was isolated from the fruit of the West African climbing plant Oubli (Pentadiplandra brazzeana Baillon). Along with pentadin, which was discovered in 1989, brazzein is the second sweet protein that was discovered in this fruit. Like other natural sweet proteins such as monellin and thaumatin, it is highly sweet. On a weight basis, brazzein is 500 times sweeter than sucrose when compared to 10% sucrose solution and 2000 times sweeter when compared to 2% sucrose solution. Its sweet perception is more similar to that of sucrose than that of thaumatin, and it presents a clean sweet taste with a lingering aftertaste. Brazzein is stable over a broad pH range from 2.5 to 8 and is heat stable at 80 °C for 4h.84... 

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