Ribitol oxidation

Fig. 9. NADP polyol dehydrogenase in sera of CCl4-poisoned mice sorbitol and ribitol oxidation (pH 9.6 polyols as substrates).

Bacterial oxidation of ribitol (adonitol XXX) affords L-adonose or L-erythropentulose (XXXI) (c/. the bacterial oxidation of sorbitol to L-sorbose). By the agency of methyl alcoholic hydrogen chloride, XXXI yields methyl L-adonoside (XXXII) and condensation of the... 

The D-galactosyl residues are the same as in disaccharide 33, and the fact that ribitol is substituted at 0-2 was evident from the methyl-ation analysis. Finally, a nonreducing tetrasaccharide was obtained, containing D-galactose, 2-acetamido-2-deoxy-D-galactose, and ribitol residues in the proportions 2 1 1. From these results, and periodate-oxidation studies, structure 36 was proposed for the neutral hexa-saccharide. 

On deamination, C-substance that had been treated with alkali and phosphatase yielded the disaccharide 2-0-(2-acetamido-2-deoxy-D-galactosyl)-D-ribitol. Periodate oxidation of C-substance had revealed that the ribitol residue is substituted at 0-2 and 0-5. 

Different preparative procedures have been shown to yield protein fractions which are able to catalyze different types of reactions with respect to their requirement of either NAD or NADP as coenzymes [cf. Eqs. (19), (20), and (21)]. In sera of mice poisoned by carbon tetrachloride we found polyol dehydrogenases catalyzing the oxidation of the following polyols (a) with NAD sorbitol, ribitol, mannitol (b) with NADP sorbitol, ribitol. Erythritol and mt/o-inositol were not attacked at all. Figures 8 and 9 show the results of these determinations performed at pH 9.6. In the NAD system sorbitol and ribitol are oxidized at exactly the same rate, while in the NADP system ribitol does not reach the rate of sorbitol. The ratio NAD NADP for sorbitol is calculated to be 4.20 and for ribitol 5.50. Mannitol is oxidized at 23% of the rate of sorbitol. 

FAD shares a lot of features with NAD+ and NADP+, but contains two new variants a sugar that is neither ribose nor deoxyribose, and a fairly complex heterocyclic base flavin. The new sugar is ribitol, non-cyclic because it contains no carbonyl group (see Section 12.3). The chemistry of FAD is concentrated in the flavin part, and features oxidation/reduction processes (see Box 11.14). 

That the anhydro product from ribitol is a derivative of 1,4-tetra-hydrofuran was established10 from the results of periodate oxidation (consumption of 1 mole of periodate per mole, with no formation of... 

The enantiomorph, also a syrup, was synthesized from 3,6-anhydro-4,5-O-isopropylidene-D-mannitol18 by periodate oxidation to the corresponding D-arabinose derivative, followed by reduction in the presence of Raney nickel.17 2,5-Anhydro-D-xylitol, 2,5-anhydro-D-ribitol, and 2,5-anhydro-D-lyxitol (1,4-anhydro-D-arabinitol)19,20 were... 

A small proportion of O-D-glucosylribitol was produced directly by hydrolysis of the teichoic acid with alkali ( see Fig. 16) this product is identical with that obtained by dephosphorylation of the hydrolysis mixture. The major products of such a hydrolysis with alkali were the isomeric monophosphates (58) and (59), in which R = 0-D-glucopyranosyl, both of which gave the O-D-glucosylribitol on enzymic dephosphorylation. The isomer (58) reduced 3 molar proportions of periodate, and the ribitol residue was oxidized, whereas the isomer (59) reduced 2 molar proportions of periodate, the ribitol residue being resistant to oxidation. Small proportions of the diphosphates (56) and (57) were also produced. Oxidation of the diphosphate (57) with periodate, followed by treatment with alkali to remove the aldehydic residues, gave a ribitol diphosphate. 

The teichoic acid shows an infrared absorption band at 1751 cm.-1, characteristic of carboxylic ester groups, which is not observed in samples from which the D-alanine residues have been removed. Removal of the u-alanine was readily effected with ammonia or hydroxylamine, when D-alaninamide or D-alanine hydroxamate were formed. The kinetics of the reaction with hydroxylamine reveal the high reactivity of its D-alanine ester linkages, which, like those in most other teichoic acids, are activated by the presence of a neighboring phosphate group. That the D-alanine residue is attached directly to the ribitol residues, instead of to the d-glucosyl substituents, was also shown by oxidation with periodate under controlled conditions of pH, when it was found that the D-alanine residues protect the ribitol residues from oxidation. Under the same conditions, all of the ribitol residues were oxidized in a sample of teichoic acid from which the D-alanine had been removed, and it is concluded that the ester groups are attached to C-2 or C-3 of the ribitol residues. 

The D-alanine, which is attached to the polymer through the characteristic, labile, ester linkages, affords protection to the ribitol during oxidation with periodate and is, therefore, attached directly to the C-2 or C-3 hydroxyl groups of the ribitol residues. 

The production of ribitol diphosphates on acid hydrolysis, and also on alkaline hydrolysis, of the product obtained after oxidation of the teichoic acid with periodate establishes the presence of ribitol phosphate residues joined to each other through phosphodiester groups. On oxidation of the polymer (o-alanine removed) with periodate, many of the ribitol residues were oxidized, and the quantitative data obtained support a structure in which there are 7-8 units in the chain. 

From the lability of the D-alanine residues to alkali, it follows that these are attached directly to the ribitol residues. Demonstration of this linkage, by oxidation of the intact polymer with periodate, is precluded by the presence of the di-O-D-glucosylribitol residues in which the ribitol is, in any case, resistant to oxidation. 

Poly(ribitol phosphate) synthetase has been found in particulate fractions from Staphylococcus aureus H, and Lactobacillus plantatrum.lt ll-m The bulk of the activity in Lactobacillus plantarum was in crude, cell-wall preparations, and the enzyme is apparently located in the membrane, although intimate association with the wall itself has been suggested. Unlike the natural teichoic acid, the enzymically synthesized ribitol phosphate polymer was readily extracted with phenol hydrolysis by acid and by alkali gave the expected products, and oxidation with periodate indicated a chain length of 5-9 units, a value which compares well with that of 8 units for the natural polymer in the walls of this organism. 

The tetrose, D-erythrose, so obtained can be oxidized with nitric acid to meso-tartaric acid. Show how this information can be organized to establish the configurations of D-arabinose, D-ribose, ribitol, and D-erythrose. 

The monomethylene-ribitol monohydrate has been obtained also from 2,4-methylene-D-talitol (XI) by periodate oxidation and hydrogenation of the resulting 2,4-methylene-D-ribose.48... 

---