Fructose irradiation

Fig. 4 illustrates the CL spectra of ribose and fructose irradiated with a UV lamp All the saccharides exhibited green chemiluminescence. The broad bands observer between 460-560 nm (blue green to green) could be attributed to phosphorescence ol adsorbed oxygen. Only ribose gave also a CL peak at 360 nm probably due tc excited carbonyl compounds. This may imply that only ribose is susceptible to UV irradiation compared to the other saccharides. 

After 447 h, the X value did not increase due to the depletion of fructose in the medium. Furthermore, the average content of Chi, Cchl, in the hairy roots and the amount of Chi, Achl, in the culture flask increased with progressing t value. On the contrary, in the culture without light irradiation (1=0 W nr2), the Cchl value decreased and was close to zero after t = 360 h. 

Early EPR work on sugar radicals led to some questionable radical assignments. There is a need to repeat some of these studies with EPR/ENDOR spectroscopy. It is therefore very encouraging to see new papers in this field with titles like Q-band EPR and ENDOR of Low Temperature X-Irradiated (3-D-Fructose Single Crystals [114] which is using all of the techniques described here to great advantage. 

When o-fructose is irradiated in aqueous solution in the presence of oxygen, the following inter-related degradation processes have been distin-guished. "... 

With the information at present available, it is not possible to advance detailed mechanisms for the processes described, and further kinetic investigations are necessary. The behavior of alditols and o-fructose on irradiation in solution support the view that primary alcohol groups are more susceptible to attack than normal secondary alcohol groups, the group at the lactol carbon atom providing an understandable exception. 

There is evidence for the presence of slow post-irradiation processes when sugar solutions are irradiated in oxygen and under vacuum. When n-glu-cose solutions are irradiated under vacuum, the absorption at 265 m/ increases steadily and attains a maximum at 20-30 hr. after irradiation has ceased. " Similarly, for D-fructose solutions irradiated in oxygen and under vacuum, the absorption maxima continue to increase for several days after irradiation has ceased. This process may be associated with the postirradiation decrease in concentration of hydrogen peroxide at a rate of 3-4 X 10 molecules min. ml. in irradiated n-fructose " and o-glucose " solutions. The occurrence of post-irradiation reactions is further demonstrated in these systems by a liberation of g9.s for 24-30 hr. after irradiation is terminated. " Further detailed examination of these interesting reactions is necessary, before it will be possible to speculate about their association with several important post-irradiation processes encountered when biological systems are irradiated. ... 

Quite similar results have been described for the action of ultrasound on D-fructose solutions. After two hours, an absorption maximum was observed at 283 mu, probably showing the formation of reductone, as mentioned by Phillips. An effect on the specific rotation was also noted, but this was much less than that observed during some irradiation studies. An x-ray investigation proved that at least 15% of the parent sugar is changed to other products, but isolation of the products has not yet been attempted. ... 

A similar distance has been calculated for the crystal structure of P-D-fructose for the H-transfer in the propagating step (see below) [12], The G value drops with increasing dose indicating that termination reactions are favoured by imperfections. There is also a characteristic change of the irradiated 2-deoxyribose crystal it turns highly hygroscopic at moderate doses. 

Based on the pyrolysis of the neat hydrochloride salts of imidazolyl tetritols, e.g. 115a-c, which leads to the 4-glycofuranosyl-lH-imidazoles, e.g. 116a-c and their anomer mixtures, Tschamber et al. [80] obtained the same pairs of C-nucleosides in one-pot procedures by microwave irradiation with a domestic Whirlpool MO 100 oven for 1.7-3 min. Mixtures containing formamidine acetate, a few drops of water, and the appropriate hexose or hexulose, i.e. D-fructose (or o-glucose), d-galactose, or L-sorbose, resulted in overall yields of 19-28% (Scheme 12.48). Irradiation for longer periods led to caramelization. 

Primary paramagnetic products of the radiolysis of yd-L-arabinose between 77 and 430K were Identified by e.s.r. as stabilized electron and alkoxy radicals with electrons localized at 0-2. Free radicals, formed by thermal decomposition of primary products, were identified and their mechanism of formation and subsequent transformation proposed. U.v., l.r., optical rotation, and magnetic susceptibility data on Jl irradiated fructose have been reported.E.s.r. has been used to study production of free radicals during the aut-oxidatlon of simple monosaccharides via spin-trapping with StS -dl-methyl-1-pyrrollne N-oxlde. The monosaccharides produced hydroxy and hydroxymethyl radical-derived spin adducts. At high pH, both hydroxy... 

After irradiation, an indicated amount of NaBH4, prepared in 0.1 N NaOH, was added to the photomodified sample. The samples were incubated for one hour at 25 C. Fructose was then added to a final concentration of 23 mM to quench the remaining NaBH4. The samples were allowed to react for an additional hour at 25° C. The samples were then activated and assayed for RuBP carboxylase activity (3). 

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