Glucose (Greek , from sweet) (C6H12O6), either glucose, or a dextrose meets in juice of many fruit and berries including grapes why there was a name of this type of sugar. Is hexatomic sugar (hexose). A glucosic link in structure of a number of di - (maltoses, sucrose and lactoses) and polysaccharides.
In the nature only D - glucose which is emitted in the form of two anomer meets: α - D - and β - D - glyukopiranoza (according to a formula I and II). The first crystallizes from water in the form of monohydrate with t of the square of 83 °C; for an anhydrous form t of the square of 146 °C, [α] D20 + 112,2 ° (water). β - Anomer crystallizes from pyridine or some other solvents; its t of the square of 148 - 150 °C, [α] D20 + 18,9 ° (water). In aqueous solution the dynamic equilibrium between several tautomer is established: α - and D - glyukofuranozy β - forms (formula III and IV) and D - glucopyranose open aldehydic (formula V) and its hydrated form (formula VI). Contents β - and α - glucopyranoses makes respectively about 64 and 36% , other tautomer - less than 1% . Equilibrium [α] D20 + 52,7 °. The steadiest tautomer - β - D - glyukopiranoza in conformation of a chair (formula VII).
At recovery of D - glucose sorbite is formed, at oxidation of aldehydic group - D - gluconic acid, at oxidation of the last - dibasic saccharic acid (primary hydroxygroup in addition is oxidized), at oxidation only of primary hydroxygroup (at protection aldehydic) - D - glucuronic acid.
Main ways of a metabolism of D - glucose:
1) glycolysis and aerobic oxidation to CO2 and H2O as a result of which ATP and other makroergichesky connections are formed;
2) synthesis oligo - and polysaccharides;
3) transformation into pentoses and others simple sugar in a pentozofosfatny cycle.
The industry receives glucose acid or enzymic hydrolysis of potato or corn starch. Development of ways of receiving glucose from tsellyulozosoderzhashchy waste of agriculture and the paper industry is of practical interest.
Quantitatively glucose is determined spektrofotometrichesky, polarimetric and hromatografichesky by methods. At gazokhromatografichesky definition glucose is previously transferred to more volatile compounds, for example to acetates of sorbite or a nitrile of gluconic acid. The most specific method of definition D - glucose - enzymatic for which carrying out use enzyme the glucose oxydas catalyzing in aerobic conditions β - D - glyukopiranoza's oxidation with formation of δ - gluconolactone and H2O2. The allocated products quantitatively determine by different methods.
Glucose is applied in medicine as nutrient and a component of krovozamenyayushchy and antishock liquids, in the food industry, in production of ascorbic and gluconic acids, biotin, etc. Fermentation of the glucose which is contained in juice of grapes and fruit, - one of stages in production of wine, and contained in hydrolyzates of starch and wood - in ethanol production.
