What is mutaroation? what will happen when a monosaccharides undergo through mutaroation

Priya sarda

Mutarotation Mutarotation is a change in the optical rotation of a solution due to a change in the equilibrium between alpha (ɑ) and beta (β) anomers, upon dissolution in the aqueous solution.The process is also known as anomerization. The phenomenon of mutarotation was discovered in 1846 by Augustin Pierre Dubrunfaut. His whole study was based on sugars.He noticed that when sugar is dissolved in water, its optical activity changes in time. From the value of 110°, it decreases to 52°. He named this phenomenon “birotation”. Later, in 1899, Lowry gave it a more appropriate name “mutarotation”, which signifies the concept behind it. When α-d-glucose dissolves in water, the optical rotation of the solution slowly changes from the initial value of + 112.2° to an equilibrium value of + 54°. If α-d-glucose dissolves in water, the rotation of the solution slowly changes from the initial value of + 18.7° to the same equilibrium value of + 54°. This gradual change in rotation to an equilibrium point is known as mutarotation. Mutarotation results from the interconversion of the cyclic hemiacetals with the open-chain form in solution. Ring opening followed by recyclization can form either the α or β anomer. At equilibrium, the solution contains 36% of the α anomer and 64% of the β anomer of glucose, with less than 0.01% of the open-chain form. In cells, an enzyme called mutarotase catalyzes the mutarotation of glucose. Although the mutarotation of glucose interconverts only anomeric pyranose forms, some aldohexoses form a four-component mixture of anomeric pyranoses and anomeric furanoses. Fructose also forms a four-component mixture of anomeric furanoses and pyranoses.