Fructose analysis

The SAM consists of a mixture of octadecyl mercaptan (OM) and two short chain disulfides, which form -S-CH2-CH2-CH2-COO" and -S-CH2-CH2-NH3+ on the surface. The short chain, charged modifiers may provide defects, or pockets, in the OM layer where the enzyme may adsorb through electrostatic interactions. At oxidizing potentials, the electrode generates a catalytic current at densities up to about 10 pA/cm when exposed to fructose solution. The enzyme electrode exhibits a response time well under a minute and the calibration curve is linear at fructose concentrations up to 0.8 mM. The biosensor prototype exhibits low susceptibility to positive interference by ascorbic acid indicating that this construct could be useful for fructose analysis of citrus fruit juice. 

In situ quantitation The in situ fluorimetric analysis was made under long-wavelength UV light (2eic = 365 nm, An > 560 nm) and is illustrated in Figure 1. The detection limits for maltose, glucose and fructose were ca. 10 ng substance per chromatogram zone. 

The separation was carried out on a TSKgel Amide-80 column 4.6 mm i.d. and 25 cm long with a mobile phase consisting of a 80% acetonitrile 20% water mixture. The flow rate was 1 ml/min and the column was operated at an elevated temperature of 80°C. The saccharides shown were 1/ rhamnose, 2/ fucose, 3/ xylose, 4/ fructose, 5/ mannose, 6/ glucose, 7/ sucrose and 8/ maltose. The analysis was completed in less than 20 minutes. These types of separations including other biomonomers, dimers and polymers are frequently carried out employing refractive index detection. 

Preliminary kinetic analysis revealed that the reactions mentioned for various sugars were close to first order with respect to the organic reactant, while the reaction order with respect to hydrogen varied between 0.5 and 2.2, being 0.7 for hydrogenation of lactose on sponge nickel and about 2 for fructose hydrogenation on CuO/ZnO. 

Other compounds identified in caramels are di-D-fructose and poly(glycosyl) dianhydrides (DFAs). DFAs were found in caramels prepared from D-fructose, D-glucose, and sucrose. The analysis was done after derivatization as TMS (per-0-trimethylsilyl) derivatives or as TMS-oxime (per-O-trimethylsilyl oxime) by... 

Liquid Chromatography. - Diasteriomeric phosphonodipeptides have been separated by ion exchange column chromatography.267 H.p.l.c. has been used for the analysis of a variety of biologically active phosphorus compounds, such as aminoacid phosphate esters,26 phosphinothrycin,269 inositol triphosphate,270 fructose diphosphate,271 pyridoxal phosphate,272 and ATP.273... 

In 1886, Brown11 discovered an organism which formed extremely tough membranes when cultivated m suitable nutrient solutions containing carbohydrates such as D-fructose, D-mannitol or D-glucose ethanol, sucrose or starch did not support membrane formation by this organism which Brown called Bacterium xylinum ) (Acetobacter xylinum). The membranes were readily soluble in cuprammonium hydroxide solution and yielded a dextrorotatory sugar upon acid hydrolysis. These properties and the results of combustion analysis led him to believe that the membrane was cellulose. 

Early reports on levan are obscured by incomplete descriptions of impure products.2 96 Greig-Smith found that Bacillus levaniformans(1) produced levan from sucrose96" in suitable nutrient solutions, but not from D-glucose, D-fructose, lactose or maltose.966 He therefore assumed that levan could only be formed from the nascent D-fructose and D-glucose resulting from the inversion of sucrose. Hydrolysis of levan yielded D-fructose only, and analysis of levan agreed with the empirical formula (C HiriOi) it was noted that levan was closely related to inulin but was not identical with it. 

An analytical method for a butterscotch would run as follows dilute the sample 1 2000 and pass through a 0.2-micron filter. The dextrose, fructose, maltose and maltotriose can then be measured directly. In contrast, the same analysis would probably require two chromatograms performed with different mobile phases using the amino-column HPLC method. 

D. Erion, S- J- Pilkis, M. R. El-Maghrabi, and W. N. Lipscomb, The allosteric site of human liver fructose 1,6-bisphosphatase. Analysis of six AMP site mutants based on the crystal structure, J. Biol. Chem. 269 27732 (1994). 

Studies using free energy calculations for the design and analysis of potential drug candidates are reviewed in section five. The chapters in this section cover drug discovery programs targeting fructose 1,6-bisphosphatase (diabetes), COX-2 (inflammation), SRC SH2 domain (osteoporosis and cancer), HIV reverse transcriptase (AIDS), HIV-1 protease (AIDS), thymidylate synthase (cancer), dihydrofolate reductase (cancer) and adenosine deaminase (immunosuppression, myocardial ischemia). 

Carrington et al. [1.124] usd thermomechanical analysis (TMA) to study the ice-crystallization temperature of 30 % (w/w) fructose, sucrose and glucose with and without sodium carboxy methyl cellulose (CMC). TMA has been used to measure the expansion of... 

The structural determination of those bicyclic compounds remained under discussion for some time, until Wickstrom et al.44 could (1) confirm the formation of fused bicyclic OZT-sugars and, more important (2) ascertain the furan forms for aldoses and the pyran form for D-fructose (Scheme 21). Those results were later confirmed by Jochims et al. through the first NMR analysis performed on OZTs.45... 

The interaction analysis between the D-fructose and its transporter is complicated due to its ability to exist in solution in four different tautomeric forms -ot,(3-pyranose and a,(3-furanose. Despite its large-scale accessibility and elucidation of its structure over a century ago,135 the chemistry of fructose126 makes also the preparation of simple derivatives in tautomeric fixed structures difficult, particularly in furanoid forms. 

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