Mutarotation

mutarotation

[¦myüd·ə·rō′tā·shən] (chemistry) A change in the optical rotation of light that takes place in the solutions of freshly prepared sugars.

Mutarotation

a gradual change in the optical activity of freshly prepared solutions of monosaccharides and some other optically active compounds. Mutarotation is a result of the inter-conversion of tautomeric forms of monosaccharides, leading to the establishment of a dynamic equilibrium between the forms. Thus, upon completion of mutarotation a solution of glucose has a specific rotation [α ]_p²⁰ of +52.5° and consists of 37 percent α-glucose with [α]_p²⁰ of +112° and 63 percent β-glucose with [a]_p²⁰ of +18.7°.

The rate of mutarotation depends on the temperature and nature of the solvent; it increases in the presence of acids and bases and particularly in the presence of bifunctional acid-base catalysts such as 2-oxypyridine. In living organisms, the mutarotation of monosaccharides and disaccharides is catalyzed by the enzyme aldose 1-epimerase.

REFERENCE

Khimiia uglevodov. Moscow, 1967.

mutarotation

mu·ta·ro·ta·tion

(myū'tă-rō-tā'shŭn), The process of changing specific rotation at a given wavelength; for example, a solution of α-d-glucose recrystallized from its solution in acetic acid and freshly dissolved in water gives a rotation of [α] ²⁰_D = +112.2°, but when recrystallized from a boiling aqueous solution (as the β-form) it shows an initial rotation of [α] ²⁰_D = +18.7°; either solution, on standing, slowly changes its specific rotation to a value of [α] ²⁰_D = +52.7°, indicating a mixture of the two anomeric forms of d-glucose. Synonym(s): birotation, multirotation

单词	mutarotation
释义	Mutarotation mutarotation [¦myüd·ə·rō′tā·shən] (chemistry) A change in the optical rotation of light that takes place in the solutions of freshly prepared sugars. Mutarotation a gradual change in the optical activity of freshly prepared solutions of monosaccharides and some other optically active compounds. Mutarotation is a result of the inter-conversion of tautomeric forms of monosaccharides, leading to the establishment of a dynamic equilibrium between the forms. Thus, upon completion of mutarotation a solution of glucose has a specific rotation [α ]_p²⁰ of +52.5° and consists of 37 percent α-glucose with [α]_p²⁰ of +112° and 63 percent β-glucose with [a]_p²⁰ of +18.7°. The rate of mutarotation depends on the temperature and nature of the solvent; it increases in the presence of acids and bases and particularly in the presence of bifunctional acid-base catalysts such as 2-oxypyridine. In living organisms, the mutarotation of monosaccharides and disaccharides is catalyzed by the enzyme aldose 1-epimerase. REFERENCE Khimiia uglevodov. Moscow, 1967. mutarotation mu·ta·ro·ta·tion (myū'tă-rō-tā'shŭn), The process of changing specific rotation at a given wavelength; for example, a solution of α-d-glucose recrystallized from its solution in acetic acid and freshly dissolved in water gives a rotation of [α] ²⁰_D = +112.2°, but when recrystallized from a boiling aqueous solution (as the β-form) it shows an initial rotation of [α] ²⁰_D = +18.7°; either solution, on standing, slowly changes its specific rotation to a value of [α] ²⁰_D = +52.7°, indicating a mixture of the two anomeric forms of d-glucose. Synonym(s): birotation, multirotation
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