Fructose determination, procedure

Haworth, Hirst and Percival23 methylated inulin by first acetylating and subsequently converting the acetate to the methyl derivative by means of dimethyl sulfate and sodium hydroxide in acetone solution, a procedure described by Haworth and Streight.24 They hydrolyzed trimethylinulin and quantitatively determined the amounts of trimethyl-D-fructose and tetramethyl-D-fructose formed. There was obtained 3.7%... 

The acetyl derivative was prepared according to the procedure of Haworth and Streight.24 After 110 precipitations of a warm benzene solution with petroleum ether, a product rotating — 23.5° resulted. Cryoscopic molecular weight determinations in benzene solution gave an average value of 9517, corresponding to 30 to 31 D-fructose residues. 

The elegant enzymatic procedure of Drawert and Kupper (59) permits determination of glucose, fructose, and (when necessary) sucrose. Glucose reacts with adenosintriphosphate (ATP) in the presence of hexokinase (HK) to produce glucose-6-phosphate. 

It was found that 3,4,6-tri-O-methyl-n-fructose consumed the theoretical quantity of periodate in 8 to 12 hours in bicarbonate buffer, as determined by the procedure of P. Fleury and J. Lange, J. pharm. chim., 17, 107 (1933). Also, at somewhat higher concentrations of reagent, the theoretical quantity of formaldehyde was obtained in 2 hours from this sugar by the procedure of J. C. Speck, Jr., and A. A. Forist, Anal. Chem., 26, 1942 (1954). These results are higher than most of those reported by W. E. A. Mitchell and E. E. Percival, J. Chem. Soc., 1423 (1954) for longer oxidation times. 

If individual monosaccharides are to be determined by a chromatographic procedure subsequent to hydrolysis, destruction losses of the individual compounds should be taken into account. For example, it has been reported that up to 90% of combined fructose may be destroyed under certain hydrolysis conditions (Mopper, 1973), and thus the pattern of monosaccharides found in samples after hydrolysis may not accurately reflect the original composition. 

C. Brice and A. S. Perlin, A chemical procedure for determination of the C 14-distribution in labeled D-fructose and other ketoses. Can. J. Biochem. Physiol, 35 (1957) 7-13. 

Amino-2-deoxy-D-glucose 6-phosphate has been determined after 7V-acetyla-tion, by the Morgan-Elson procedure. The method has been used in a study of L-glutamine D-fructose 6-phosphate aminotransferase [EC 2.6.1.16] and 2-amino-2-deoxy-D-glucose 6-phosphate aldo-ketoisomerase [EC 5.3.1.10] activities. 

PEO 2000 for synthesis (Merck-Schuchardt) was chosen for osmotic vapour pressure measurements. Fructose p.a. (Fa. Merck) was used as calibrating substance. For the membrane osmosis PEO 35000 (Hoechst AG) was taken. This product was fractionated by slowly cooling a solution (10 wt.% PEO) of a mixture water/acetone (15/85 wt./wt.). This procedure was carried out to make sure, that the sample doesn t contain portions of low molecular polymers <20000 g/mol. The membranes (Sartorius, Gottingen, regenerated cellulose Cat.-Nr. 11539) have a lower limit for determination of molar masses of 20000 g/mol. 

A kinetic determination of 2-ketohexoses has been based on their reactions with the cysteine-sulphuric acid reagent sorbose gave a distinct absorption spectrum, whereas o-fructose, psicose, and tagatose were distinguished from each other by differences in the rate of increase of the absorbance at 412 nm. Procedures used in colorimetric ultramicroassays of reducing sugars, and... 

Using chromatographic and heat inactivation procedures, Pazur succeeded in separating transfructosidase from Aspergillus oryzae cultures, containing a mixture of transglucosidase, invertase, and maltase. In tracer experiments the C -fructosyl units in radioactive sucrose were transferred to nonradioactive raffinose. Hydrolysis of the radioactive fructosylraffinose into fructose and melibiose, followed by a determination... 

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