Trehalose
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| Trehalose | |
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| Molecular formula | C12H22O11.2H2O |
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| CAS number | [] |
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| Properties | |
| Molar mass | 342.296 g/mol |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Trehalose, also known as mycose, is an alpha-linked (disaccharide) sugar found extensively but not abundantly in nature. It can be synthesised by fungi, plants and invertebrate animals. It is implicated in anhydrobiosis—the ability of plants and animals to withstand prolonged periods of desiccation. The sugar is thought to form a gel phase as cells dehydrate, which prevents disruption of internal cell organelles by effectively splinting them in position. Rehydration then allows normal cellular activity to be resumed without the major, generally lethal damage, that would normally follow a dehydration/reyhdration cycle. Trehalose has the added advantage of being an antioxidant.
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[edit] Chemistry
Trehalose was first isolated from ergot of rye. Emil Fischer first described the trehalose-hydrolyzing enzyme in yeast. Trehalose is a non-reducing sugar formed from two glucose units joined by a 1-1 alpha bond giving it the name of α-D-glucopyranosyl-(1→1)-α-D-glucopyranoside. The bonding makes trehalose very resistant to acid hydrolysis, and therefore stable in solution at high temperatures even under acidic conditions. The bonding also keeps non-reducing sugars in closed-ring form, such that the aldehyde or ketone end-groups do not bind to the lysine or arginine residues of proteins (a process called glycation). Trehalose has about 45% the sweetness of sucrose. Trehalose is less soluble than sucrose, except at high temperatures (>80°C). Trehalose forms a rhomboid crystal as the dihydrate, and has 90% of the calorific content of sucrose in that form. Anhydrous forms of trehalose readily regain moisture to form the dihydrate.
Anhydrous forms of trehalose can show interesting physical properties when heat treated.
[edit] Biochemistry
Trehalose is metabolized by a number of bacteria, including Streptococcus mutans, the common oral bacteria responsible for oral plaque.
The enzyme trehalase, a glycoside hydrolase, present but not abundant in most people, breaks trehalose into two glucose molecules, which can then be readily absorbed in the gut.
Trehalose is the major carbohydrate energy storage molecule used by insects for flight. One possible reason for this is that the double glycosidic linkage of trehalose, when acted upon by an insect trehalase, releases two molecules of glucose, which is required for the rapid energy requirements of flight. This is double the efficiency of glucose release from the storage polymer starch, for which cleavage of one glycosidic linkage releases only one glucose molecule.
[edit] Natural sources
- Trehala manna
- Locust
- Resurrection plant
- Fungi
[edit] Use
Trehalose has been accepted as a novel food ingredient under the GRAS terms in the U.S. and the EU. Trehalose has also found commercial application as a food ingredient. However, less-soluble and less-sweet than sucrose, trehalose is seldom used as a direct replacement for conventional sweeteners, such as sucrose, regarded as the "gold standard." The development has come out of Japan, where enzyme-based processes have been developed to convert wheat and corn syrups. It is also used as a protein stabilizing agent in research [1]and in at least one biopharmaceutical formulation, the monoclonal antibody trastuzumab, marketed as Herceptin.
[edit] solubility
68.9 g/100 g H2O at 20 °C http://www.iupac.org/publications/pac/2002/pdf/7407x1263.pdf.
