mutarotation

変旋光

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/09/05 13:29:03」(JST)

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Mutarotation is the change in the optical rotation because of the change in the equilibrium between two anomers, when the corresponding stereocenters interconvert. Cyclic sugars show mutarotation as α and β anomeric forms interconvert.^[1] The optical rotation of the solution depends on the optical rotation of each anomer and their ratio in the solution.

Mutarotation was discovered by French chemist Dubrunfaut in 1846, when he noticed that the specific rotation of aqueous sugar solution changes with time.^[2]^[3]

Measurement

The α and β anomers are diastereomers of each other and usually have different specific rotations. A solution or liquid sample of a pure α anomer will rotate plane polarised light by a different amount and/or in the opposite direction than the pure β anomer of that compound. The optical rotation of the solution depends on the optical rotation of each anomer and their ratio in the solution.

For example if a solution of β-D-glucopyranose is dissolved in water, its specific optical rotation will be +18.7. Over time, some of the β-D-glucopyranose will undergo mutarotation to become α-D-glucopyranose, which has an optical rotation of +112.2. Thus the rotation of the solution will increase from +18.7 to an equilibrium value of +52.5 as some of the β form is converted to the α form. The equilibrium mixture is actually about 64% of β-D-glucopyranose and about 36% of α-D-glucopyranose, though there are also with traces of the other forms including furanoses and open chained form.^[4]

The observed rotation of the sample is the weighted sum of the optical rotation of each anomer weighted by the amount of that anomer present. Therefore one can use a polarimeter to measure the rotation of a sample and then calculate the ratio of the two anomers present from the enantiomeric excess, as long as one knows the rotation of each pure anomer. One can monitor the mutarotation process over time or determine the equilibrium mixture by observing the optical rotation and how it changes.

Reaction mechanism

Reaction mechanism for the interconversion of α and β anomers

References

^ IUPAC Gold Book mutarotation
^ Derek Horton (2008). "The Development of Carbohydrate Chemistry and Biology". Carbohydrate Chemistry, Biology and Medical Applications: 1–28. doi:10.1016/B978-0-08-054816-6.00001-X.
^ Augustin-Pierre Dubrunfaut—An early sugar chemist. Hewitt G. Fletcher, J. Chem. Educ., 1940, 17 (4), p 153, doi:10.1021/ed017p153
^ Francis Carey (2000). Organic Chemistry (4th, McGraw-Hill Higher Education Press ed.).

English Journal

Mechanism of mutarotation in supercooled liquid phase: Studies on L-sorbose.

Wlodarczyk P, Paluch M, Grzybowski A, Kaminski K, Cecotka A, Ziolo J, Markowski J.SourceInstitute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007 Katowice, Poland.
The Journal of chemical physics.J Chem Phys.2012 Sep 28;137(12):124504.
We have studied mutarotation in anhydrous supercooled L-sorbose by means of dielectric spectroscopy. The phenomenon observed in L-sorbose is much faster than in the structurally similar D-fructose. The kinetics of this process has been determined by applying 1st order kinetics model. Activation ener
PMID 23020340

Identification of rare 6-deoxy-D-altrose from an edible mushroom (Lactarius lividatus).

Tako M, Dobashi Y, Tamaki Y, Konishi T, Yamada M, Ishida H, Kiso M.SourceDepartment of Subtropical Bioscience and Biotechnology, University of the Ryukyus, Nishihara, Okinawa, Japan. tako@agr.u-ryukyu.ac.jp
Carbohydrate research.Carbohydr Res.2012 Mar 1;350:25-30. Epub 2011 Dec 26.
6-Deoxy-L-altrose is well known as a constituent sugar moiety of lipopolysaccharides in Gram-negative bacteria. However, its isomer, 6-deoxy-D-altrose, is little known. Identification of 6-deoxy-D-altrose isolated from a polysaccharide extracted from an edible mushroom (Lactarius lividatus), its com
PMID 22277536

Japanese Journal

Crystal Structure, Solubility, and Mutarotation of the Rare Monosaccharide D-Psicose

, , , , , ,
Bulletin of the Chemical Society of Japan 84(6), 678-678, 2011
NAID 130004152933

Crystal Structure, Solubility, and Mutarotation of the Rare Monosaccharide D-Psicose

Fukada Kazuhiro,Ishii Tomohiko,Tanaka Katsushi [他],YAMAJI Masatsugu,YAMAOKA Yuya,KOBASHI Ken-ichi,IZUMORI Ken
Bulletin of the Chemical Society of Japan 83(10), 1193-1197, 2010-10-15
NAID 10026699192

リン酸塩による変旋光触媒作用を利用したスクロースバイオセンサーの開発

浅見和広,稲葉英,太田口和久
化学工学論文集 36(1), 51-56, 2010-03-20
通常スクロース測定用酵素電極にはインベルターゼ（INV），ムタロターゼ（MUT），グルコースオキシダーゼ（GOD）の3種の酵素を使用するが，中でもMUTは非常に高価である．本研究では，MUTを使用しない安価な2種類の酵素から成る電極を作成し，スクロース濃度測定の可能性について検討した．グルタルアルデヒドを用いてGODを白金に架橋結合した酵素電極（GOD電極）と，GODとINVを併せて白金に架橋結合 …
NAID 10027040227

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