B-Arabinose

Figure 2. Enzymic measurement of a-L-arabinan in fruit-juice concentrates, (a) Effect of time of incubation of sample with arabinofuranosidase and ndo-arabinanase. Diluted pear juice concentrate (1 10 0.1 ml) or sugar beet arabinan solution (0.1 ml) was incubated with an aliquot (0.1 ml) of arabinofuranosidase (5 units) plus ndo-arabinanase (0.2 units) at 35 C and pH 4.0. Aliquots were analysed for arabinose. (b) Arabinose determination using the NAD-Galactose Dehydrogenase method. Arabinose solution (0.2 ml, 50 digrams) was incubated with Tris-HCl buffer (2.5 ml, pH 8.6), NAD (0.1 ml, 10 m ml) and galactose dehydrogenase (20/i, 140 milliunits) at 35°C. Absorbance (340 nm) was measured after various time intervals.

FIGURE 3.3 Primary monomeric structures of sugars constituting hemicelluloses (a) xylose, (b) arabinose (pentoses), (c) mannose, (d) glucose, (e) galactose (hexoses), (f) 4-O-methyl-D-glucuronic acid, and (g) galaturonic acid... 

B-L-Arabinose (natural) [87-72-9] M 150.1, m 158 , [a]o +104 (c 4, H2O after 24h). Crystd slowly twice from 80% aq EtOH, then dried under vacuum over P2O5. 

Figure 4.21 The polypeptide chain of the arabinose-binding protein in E. coli contains two open twisted a/P domains of similar structure. A schematic diagram of one of these domains is shown in (a). The two domains are oriented such that the carboxy ends of the parallel P strands face each other on opposite sides of a crevice in which the sugar molecule binds, as illustrated in the topology diagram (b). [(a) Adapted from J. Richardson.)...

Fig. 1 Schematic diagram of the chromatographic separation (A) and the fluorescence scan (B) of a sugar mixture containing 1 pg substance per chromatogram zone. Lactose (1), fructose (2), arabinose (3), xylose (4), rhamnose (5), mixture (G).

Method B (one-pot procedure)-. 5 g (33 mmol) of L-arabinose. 12 mL of ethanol and 4mL (36.7 mmol) of bcnzylaminc arc heated on a steam bath for 5 to 10 min to give a clear solution. After cooling, 2.5 mL of anliyd hydrogen cyanide are added. Spontaneous crystallization of the product begins within a few minutes. After cooling for 2 h with an ice-bath, the product is isolated by filtration and washed with ethanol yield 7.0-7.5g (79-85%) nip 129-131 C after recrystallization from ethanol mp 130-132 C. 

The stems of the tree were foimd to contain polysaccharides consisting of arabinose, galactose and galacturonic acid and only minor amoimts of rham-nose. Structural studies indicate that the polymeric material consists of 1,4-linked galacturonic acid residues, terminal, 1,4-, 1,6- and 1,3,6 galactose units and terminal and 1,5-linked arabinofuranose residues. Further studies must be performed on this in order to determine what type of pectin it can be classified as. The Hnkage data indicate that both AG-I and AG-II are present. This polymer was shown to activate polyclonal B-cells [78]. 

Fig. 7.—Predicted (- -) and Fragment (—) Circular Dichroism Spectra /3-L-Arabinose Calculated from (a) a-D-Xylose, and (b) Methyl /3-L-Aiabinoside a-L-Arabinose Calculated from (c) j3-D-Xylose, and (d) Average Calculated for /3-L-Arabinose Methyl a-L-Arabinoside Calculated from (e) Methyl /3-D-Xyloside, and (f) Methyl /3-L-Arabinoside. (Redrawn from Ref. 6.)...

The approximate times of osazone formation in minutes are given in Table 111,139. The product from mannose is the simple hydrazone and b practically white. Arabinose osazone separates first as an oil, wlxilst that from galactose is highly crystalline. Lactose and maltose give no precipitate from hot solution. 

Figure 20 Post-column detection of mono- and disaccharides with 4-amino-benzoylbenzamide. Column CarboPac PA-1. Gradient 1-10 mm NaOH (0-20 min.), 10-20 mM NaOH (20-35 min). Flow rate 1 ml/min. Detection absorbance at 400 nm after reaction with 4-aminobenzoylhydrazide. (a) Standard mixture of fucose (1), arabinose (2), galactose (3), glucose (4), xylose and N-acetylglucosamine (5 and 6), allose (7), 3-fucosyllactose (8), fructose (9), lactose (10), Man-(3-(l,4)-GlcNac. (b) Normal urine, (c) Urine from a child with (3-mannosidosis. (Reproduced with permission of Academic Press from Peelen, G. O. H., de Jong, J. G. N., and Wever, R. A., Anal. Biochem., 198, 334, 1991.)...

An Arbuzov reaction between gem-dibromocyclopropanes yields phosphonate esters (55) accompanied by debrominated compounds successful reaction requires the presence of traces of water (and is thus not the normal Arbuzov reaction) which, by studies with D2O, has been shown to supply the a-proton of (56), Normal Arbuzov reactions, using ethyl diphenyl phosphite, have been used to prepare a phosphonate isostere of B-D-arabinose-1,5-diphosphate. ... 

A comprehensive study of KDO 8-phosphate synthetase has been reported by Ray.137 The author purified the enzyme 450-fold from crude extracts of Escherichia coli B cells. The synthetase has a molecular mass of 90,000 6,000 daltons and is composed of three identical subunits having an apparent molecular mass of32,000 4,000 daltons. Two pH optima were observed, one being at pH 4.0-6.0 in succinate buffer, and the other, at pH 9.0 in glycine buffer. The isoelectric point of the enzyme is 5.1. The enzyme has an apparent KM for D-arabinose 5-phosphate of 20 pM and an apparent KM for enolpyruvate phosphate of 6 pM. 

Figure 28.5, illustrates TLC of an urine sample by the normal TLC-technique vis-a-vis the wedged-tip technique (Figure 28.5(Z>)). One may clearly visualize the beautiful separated bands in the latter as compared to the several odd and irregular-shaped spots in the former. Both the clarity of separation and the reproducibility of the results are predominant in the latter technique. Figure 28.5 (a) and (b) represent the typical analysis of a urine sample containing glucose, arabinose, lactose and fructose respectively.

Figure 28.5 (a) TLC-Normal technique 28.5 (b) TLC-Wedged-Tip Technique 1 = Glucose (Blue-Violet) 2 = Arabinose (Blue) 3 = Lactose (violet) 4 = Fructose (Red) ... 

HTHARAC helix turn helix, arabinose operon control protein E(M)B 0(0) 0(0) 1BL0... 

Fig. 2.106. Separation and identification of various anthocyanin red fruit juices a, grape b, blueberry c, raspberry and d, red currant. Mobile phase water-acetonitrile-formic acid (84 6 10, v/v). Abbreviations Dp delphidin, Cy cyanidin, Pt petunidin, Pn peonidin, Mv malvidin, glu glucose, gala galactose, ara arabinose, ruti rutinose, sopho sophorose, sam sambubiose, xyl xylose. Reprinted with permission from J.-P. Goiffon et al. [241].

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