L-Arabinose-1-phosphate

Aldoses react with ATP in a phosphotransferase-catalyzed reaction (C 1.1) either to sugar-l-phosphates, e.g., D-galactose-l-phosphate and L-arabinose-1-phosphate, or to sugar-co-phosphates, e.g., D-glucose-6-phosphate (Fig. 27), D-mannose-6-phosphate, D-galactose-6-phosphate, and D-ribose-5-phosphate. Aldose-l-phosphates may also be formed from co-phosphates by mutases (Fig. 27) with 1,co-diphosphates as intermediates. 

Arabinose-1-phosphate (ara-l-P) has already been isolated as barium salt from the reaction mixture, and the mechanism of trans-arabinosylation has also been investigated. It has been clarified that nucleoside phosphorylases are involved in the trans-arabinosylation reaction, and ara-l-P is the reaction intermediate for arabinoside preparation. ... 

That the same enzyme,28 sucrose phosphorylase, is involved in the reaction of L-arabinose is indicated by the following observation. When L-arabinose is added to a mixture containing the enzyme, D-glucose-1-phosphate and D-fructose, of which the last is present in insufficient concentration to give the maximum rate of sucrose formation, an increase... 

This enzyme [EC 2.4.1.7], also known as sucrose gluco-syltransferase, catalyzes the reaction of sucrose with orthophosphate to produce D-fructose and a-D-glucose 1-phosphate. In the forward reaction, arsenate may replace phosphate as the substrate. However, the resulting product is unstable in aqueous solutions. In the reverse reaction, various ketoses and L-arabinose may replace D-fructose. See Arsenolysis... 

Deoxy-D-/w<2 0-2-octulosonate aldolase (EC 4.1.2.23), also named 2-keto-3-deoxyoctonate (KDO) aldolase catalyzes reversible condensation of pyruvate with D-arabinose to form KDO. Preliminary investigations of the substrate specificity indicated a high specificity for KDO in the direction of the cleavage. KDO aldolase has been tested in the condensation reaction with several unnatural substrates including D-ribose, D-xylose, D-lyxose, L-arabinose, D-arabinose 5-phosphate and Af-acetylmannosamine, giving poor yield in all cases [64],... 

Lipid A of Salmonella contains glucosamine, fatty acid and phosphate, with variable amounts of phosphoethanolamine and 4-amino-L-arabinose. Two molecules of glucosamine are pi,6-linked to each other and are very heavily substituted by fatty acyl residues. There are four molecules of 3-hydroxymyristate, seven molecules of long-chain fatty acid and three molecules of non-hydroxylated fatty acid per disaccharide, producing an extremely hydrophobic structure. The first glucosamine residue is attached to phosphate at C-1 and, thence, to ethanolamine and the second is substituted at C-4 by phosphate and, thence, can be attached to 4-amino-L-arabinose. For reviews of this structure see Westphal et al (1981) and Reitschel et al. (1981). It should be noted that lipid A is microheterogeneous. 

Other Aldolases. In addition to the DHAP aldolases, we have conducted preliminary investigations of two other aldolases. KDO synthase (E.C. 4.1.2.16) catalyzes the formation of 2-keto-3-deoxy-L-nrahi/io-octulosonic acid 8-phosphate (KDO-8-P) from arabinose 5-phosphate and PEP (Scheme 10) (29). KDO is an integral component of Gram-negative bacterial cell walls, and derivatives of KDO are of interest as inhibitors of cell wall formation (30, 31). 

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