Mutarotation, of turanose

Turanose crystallizes in well-formed prisms (see Fig. 5) it is anhydrous, shows the composition CuHhOu by combustion analysis, its melting point is 157°, and it exhibits a large and rapid mutarotation in water from an initial [a]o22 of about +22° to the final value +75.3° in the course of about thirty minutes. Isbell and Pigman26 found for the mutarotation of turanose at 20.7°, [a]n +27.3° (initial) —> +75.8°... 

Structure. As shown by G. Tanret, the sugar is hydrolyzed to D-fructose and D-glucose by yeast a-D-glucosidase and, hence, must be an a-D-glucoside. This conclusion receives confirmation from the lack of hydrolysis of the disaccharide by almond emulsin 110). The above evidence and the resistance of the sugar to oxidation by alkaline hypoiodite solutions, coupled with its reduction of alkaline copper salt solutions, show that the unsubstituted hemiacetal group belongs to the fructose component. The mutarotation of turanose resembles that of fructose and probably is caused... 

Reducing oligosaccharides show many of the properties of simple sugars such as mutarotation, reduction of alkaline solutions of salts of heavy metals, existence of and p)ranose and furanose isomers, and ready oxidation and reduction. Nonreducing sugars behave as alcohols unless the linkages are hydrolyzed by acids. The linkages are usually stable to the action of alkalies, but a few (e.g., turanose) are alkali-labile. 

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