Sucrose spectra

Figure 1. Triboluminescence Spectrum of Sucrose. Spectrum obtained with 5, 10 sec acquisitions and a 25 /im slit using a 142X chevron detector.

Figure 7.26 Gradient-enhanced TOCSY spectrum of 10 mM sucrose in D. O recorded at 400 MHz by using modified MLKV-16 pulse sequence.

Gradient-enhanced 2D TOCSY spectrum of 10 mMof sucrose in D..,0 is shown in figure 7.26. The clean spectrum obtainable without any noise and without the nece.ssity of any phase cycling illustrates the power of this new technique in modern NMR spectroscopy. 

Internal-displacement reactions to give sugar anhydrides are well known, and anhydro derivatives of sucrose have been prepared by treatment of the respective sulfonates or chlorides with a base. Buchanan and coworkers described the synthesis of 3, 6 -anhydrosucrose by treating 2,3,4,6,l, 3, 4 -hepta-0-acetyI-6 -0-(p-ni-trophenylsulfonyl)sucrose with sodium ethoxide in ethanol for 2 h under reflux.18 Similar treatment of 2,3,4,l, 3, 4, 6 -hepta-0-acetyl-6-chloro-6-deoxysucrose (46) with sodium methoxide in methanol, followed by acetylation, gave crystalline 2,4,l, 3, 4, 6 -hexa-0-acetyl-3,6-anhydrosucrose (47) in 83% yield.81 The H n.m.r. spectrum of 47... 

The fragmentation pattern of 2,3,6,l, 3, 4, 6 -hepta-0-acetyl-4-0-(trideuterioacetyl)sucrose (79) and 2,3,4,6,l, 3, 6 -hepta-0-acetyl-4 -0-(trideuterioacetyl)sucrose (80) has been described.44 The mass spectrum of compound 79 contains fragment ions corresponding to the two oxycarbonium ions (81) and (82). Likewise, for 80, ions 83 and 84 were observed. For compound 79, the hexopyranosyl cat-... 

Figure 5. (A) Protein-difference spectrum for the binding of cellobiose onto CBH I (7.6°C). The baseline (a) was recorded (double beam spectrophotometer) with 0.720 mM cellobiose in the measuring cuvette and 0.720 mM sucrose in the reference cuvette. The difference spectrum (b) was recorded after addition of 9.3 /iM CBH I to both cuvettes.

Fig. 4. (a) Conventional 500 MHz HMBC spectrum of sucrose octaacetate in deuteriochlo-roform, and (b) HMBC spectrum with ti-noise corrected by reference deconvolution. (Reproduced, with permission, from Signal Treatment and Signal Analysis in NMR, ed. D.N. Rutledge, Elsevier, Amsterdam, 1996)... 

Acetates. Because of the significant interest in selective acetylation reactions of sucrose, the need for a convenient and unambiguous method of identification has been recognized (34,35). The position of an acetyl group in a partially acetylated sucrose derivative can be ascertained by comparison of its H-nmr acetyl methyl proton resonances after per-deuterio acetylation with those of the assigned octaacetate spectrum. The synthesis of partially acetylated sucroses has generally been achieved either by way of selectively protected derivatives such as trityl ethers and cyclic acetals or by direct selective acetylation and deacetylation reactions. 

The structures of vanicosides A (1) and B (2) and hydropiperoside (3) were established primarily by one- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy techniques and fast atom bombardment (FAB) mass spectrometry (MS).22 The presence of two different types of phenylpropanoid esters in 1 and 2 was established first through the proton (4H) NMR spectra which showed resonances for two different aromatic substitution patterns in the spectrum of each compound. Integration of the aromatic region defined these as three symmetrically substituted phenyl rings, due to three p-coumaryl moieties, and one 1,3,4-trisubstituted phenyl ring, due to a feruloyl ester. The presence of a sucrose backbone was established by two series of coupled protons between 3.2 and 5.7 ppm in the HNMR spectra, particularly the characteristic C-l (anomeric) and C-3 proton doublets... 

The 3700-2700-cm-1 region is less easy to interpret than the region below 1700 cm-1. Nevertheless, comparative study of intensities of the C-H vibrations permitted differentiation of D-fructose from D-glucose and sucrose. It was found187 that the asymmetrical vibration pas(C-H) for CH2 in d-fructose is stronger than the symmetrical vibration the opposite was observed for D-glucose, and the spectrum of sucrose exhibits almost the same intensity for the two vibrations. This result (see Fig. 19), which could... 

Bands Observed" in the Laser-Raman Spectrum of Sucrose in Aqueous Solution... 

A number of hydration of 21 for sucrose, and of 10 for D-glucose, were found213 from the i.r. spectra of these sugars at 25°, compared to the i.r. spectrum of water at higher temperatures. The same method of determination of hydration numbers was applied221 to eight different sugars at 25°. The influence of temperature and concentration on the hydration number... 

Fig. 18. Substrate spectrum of sucrose synthase (EC 2.4.1.13) from rice grains in the cleavage reaction of sucrose (24) with nucleoside diphosphates [272,273]...

However, nucleoside diphosphates (NDP) are still expensive substrates, which can be obtained from much more cheaper nucleoside monophosphates (NMP). In this respect we have combined the SuSy-catalyzed cleavage of sucrose with the enzymatic formation of NDPs from NMPs catalyzed by nucleoside monophosphate kinase (NMPK, EC 2.7.4.4) or myokinase (MK, EC 2.7.4.3), including in situ regeneration of ATP with pyruvate kinase (PK, EC 2.7.1.40) (Fig. 20) [272]. Testing the substrate spectrum of four different kinases disclosed that none of them accepted dTMP as substrate [272], However, dUMP was well accepted by NMPK and dUDP-activated glucose could also substitute dTDP-activated glucose as precursor for the synthesis of activated deoxysugars (see below). The excellent enzyme stabilities under synthesis... 

Figure 7. Top. (M-H)- ion of sucrose formed by desorption with pulsed CO2 laser beam. Bottom. Dissociation upon irradiation with the cw CO2 laser. Experimental conditions are same as in the top spectrum.

---