Department of Medical Immunology and Genetics, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
Several sweet-tasting proteins (Brazzein, Curculin, Monellin, Mabinlin, Miraculin Pentadin and Thaumatin) have been identified. These proteins have been found from plants that grow in several tropical rainforests, but extractions of sweet tasting proteins from the natural sources are very difficult. Low-calorie sweeteners are important among consumers affected by diseases linked to the consumption of sugar such as obesity, diabetes, caries, cancer, and hyperlipemia. These proteins can be used as natural low-calorie sweeteners. Most sweeteners are small molecular weight molecules can interact with small cavities in active site of T1R2-T1R3 sweet receptors and produce the sensation of sweetness in human. Sweet tasting proteins have different molecular lengths. Thaumatin (22 kDa protein) and Monellin (10.7 KDa) are 3000 times sweeter than sucrose on a weight basis. Pentadin (12 KDa) and Brazzein (6.5 kDa protein) Fruits of the plant Pentadiplandra brazzeana Baillon found in some countries of tropical Africa are also compounds which have characterizes with sweetness about 2000 times higher than sucrose. Monellin is 100 000 times sweeter than sucrose on a molar basis; mabinlin (12.4 kDa protein) is around 400 times sweeter than sucrose on molar basis that grows in china. Curculin is a dimer of two identical Polypeptides with a calculated molecular mass of 24.9kDa that which grows in some parts of Malaysia. All of these genes have been cloned and purified at very low levels. We produced a synthetic gene encoding brazzein for cheaper mass production of recombinant protein in Maltose-binding protein (MBP) and Glutathion-S-Transferase (GST) for large-scale protein expression in E. coli.
Results: However, there has been an increasing demand for low-calorie sweeteners. Sweet plant proteins are potential sugar substitute as a major advantage to artificial sweeteners in the food and soft drink industries.
In order to reach the market, the expressed protein by the biotechnological approach will be required for high levels of products.
Keywords:Sweet protein, Recombinant, protein expression.