Fructofuranoside, methyl

Figure 4. Mean integrated response of the chorda tympani nerve discharge in the gerbil to sucrose (A), methyl a-o-glucopyranoside (A), methyl (S-o-glucopy-ranoside ( ), methyl f -o-fructofuranoside ( ), methyl a-o-fructofuranoside (O), methyl a-o-fructopyranoside ( ), methyl p-n-fructopyranoside (Y), 1,5-anhydro-o-mannitol (Q), fructose (equilibrium mixture, 25°C) (V) Responses are relative to the maximum sucrose response.

Benzyl dimethyl-a-D-fructofuranoside Methyl dimethyl-a-D-fructofuranoside liquid +57.1 Dioxan 95... 

Methyl-D-fructofuranosides, 445 -447 4-Methyl-5-(2-hydroxyethyl)thiazole, 268-269 O-Methylsucroses, degradation, 447 Methyl trifiate, 187... 

However, some carbohydrates with a terminal D-fructofuranose residue are not suitable substrates for levan formation, e. g., methyl /3-d-fructofuranoside and inulin,64 even in the presence of enzymes98 which hydrolyze these substrates. 

The specificity of levansucrase98 is dependent not only on the d-fructoside but also on the aldoside residue of the substrate. Neither inulin nor methyl D-fructofuranoside was hydrolyzed by levansucrase, and even when these two substrates were hydrolyzed by inulase (prepared from inulin-fermenting Torula yeast) or by yeast invertase respectively, no levan formation occurred with levansucrase. However, neither methyl D-fructofuranoside nor inulin inhibited levan formation from sucrose by levansucrase. No levan was formed from potassium D-glucose... 

There is also strong evidence for the type of glycosidic linkage existing in the fructose constituent of the sucrose molecule. Schlubach and Rauchalles18 showed that invertase hydrolyzes sucrose and methyl /3-D-fructofuranoside at approximately the same rate, indicating that... 

The same holds for substitution at C3 and C5 of the fructofuranose moiety of sucrose neither melezitose (XV)61 nor o-D-glucopyranosyl-/3-D-xyloketofuranoside (XVIc)22 is hydrolyzed by yeast saccharase. As might have been expected from the experience with glycosidases, any change in the configuration of the fructon of sucrose results in stereoisomers unhydrolyzable by /3-fructofuranosidase. Thus, methyl and benzyl a-D-fructofuranosides,62 isosucrose (= /3-D-glucopyranosyl-a-D-fructo-... 

R. Cortes-Garcia, L. Hough, and A. C. Richardson, Acetalation of sucrose with concomitant fission of the glycosidic bond. Some new acetals of D-glucose and methyl a-D-fructofuranoside, J. Chem. Soc., Perkin Trans. 1 (1981) 3176-3181. 

D-fructofuranoside. The methylation results did not determine the two alpha or beta glycosidic configurations about the biose junction, and XV, like II, therefore had four possible configurations. 

Comparisons made with the same invertase solutions showed that the methyl and benzyl / -D-fructofuranosides were hydrolyzed 13.5 and times, respectively, more slowly than sucrose, and that the rates... 

When the original methyl D-fructofuranoside sirup was fermented with yeast, the unstable beta isomer was selectively eliminated and the residue yielded a crystalline methyl D-fructoside melting at 81° and with [a] D +93° in water. The ring structure of this new isomer was proved to be furan by methylation to the liquid tetramethyl derivative, of [a] °D +129.4°, and subsequent hydrolysis to 1,3,4,6-tetramethyl-D-fructofuranose (structure IX) with the correct specific rotation of +29.8° in water. Both the methyl D-fructoside and its fully methylated derivative were therefore of the alpha configuration, since the latter was more dextrorotatory than the tetramethyl-D-fructose and also since the former was more dextrorotatory than the isomer, of [a] D —51°, unstable to invertase. Similar work with the benzyl D-fructofuranoside sirup produced the crystalline alpha isomer, melting point 89°, [a] D +45.7° in water, the liquid tetramethyl derivative, [a] D +83.3° in chloroform and, after acid hydrolysis of the latter, 1,3,4,6-tetramethyl-D-fructofuranose. 

Although dilute aqueous acid hydrolyzed the methyl and benzyl a-D-fructofuranosides approximately 8 and 16 times as rapidly as sucrose, their method of preparation showed them to be unaffected by any of the enzymes active in a fermenting yeast suspension. Purified yeast invertase, proven free of a-D-glucosidases (maltases), could therefore contain no enzyme capable of hydrolyzing the above two a-D-fructo-furanosides, but did contain constituents that readily cleaved the beta isomers and also sucrose. The latter is accordingly a /S-D-fructofuranos-ide. When the evidence is put in this way, the present uncertainties as to whether purified invertase preparations include one or a number of /3-D-fructofuranosidases, and whether or not sucrose, methyl and... 

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