Deoxy-D-manno-2-octulosonate 8-phosphate

Deoxy-D-manno-2-octulosonate Aldolase (E.C. 4.1.2.23) and 3-Deoxy-D-manno-2-octulosonate 8-Phosphate Synthetase (E.C. 4.1.2.16)... 

Deoxy-D-manno-2-octulosonate 8-phosphate synthetase, also known as phospho-... 

In the biosynthesis of bacterial lipopolysaccharides 3-deoxy-D-manno-2-octulosonate 8-phosphate (KDO 8-P) synthetase (EC 4.1.2.16) is involved in catalyzing the irreversible aldol reaction of... 

M. D. Bednarski, D. C. Crans, R. Dicosimo, E. S. Simon, P. D. Stein, and G. M. Whitesides, Synthesis of 3-deoxy-i>manno-2-octulosonate-8-phosphate (KDO-8-P) from D-arabinose Generation of D-arabinose-5-phosphate using hexokinase, Tetrahedron Lett. 29 427 (1988). 

Kdo-synthetase catalyzes the aldol addition of enolpyruvate phosphate with D-arabinose 5-phosphate (see Scheme 13), which gives 3-deoxy-r> manno-2-octulosonic add 8-phosphate (Kdo 8-phosphate). Kdo is an important component of oligosaccharides of Gram-negative bacteria. 

CMP-KDO synthetase (cytidine-5 -triphosphate cytidine-5 -mon-ophosphate-3-deoxy-D-manno-octulosonate cytidylyltransferase), the next enzyme in the pathway, catalyzes the formation of the nucleotide sugar, CMP-KDO from CTP and KDO. This enzyme was first studied by Ghalambor and Heath (IT). We have purified this enzyme to homogeneity (27). T i apparent K values for CTP nd KDO in the presence of 10 mM Mg were determined to be 2 x 10 M and 2.9 x 10 M, respectively. The enzy tic reaction was dependent upon the addition of CTP, KDO and Mg but did not require a reducing agent. The formation of CMP-KDO was not inhibited by the addition of CDP, CMP, KDO-8-phosphate or N-acetylneuraminic acid to the complete reaction mixture. In agreement with Ghalambor and Health (17), neither KDO-8-phosphate nor N-acetylneuraminic acid could substitute for KDO in the reaction mixture. Pyrophosphate, one of the end products, is a weak inhibitor of the reaction with an apparent Ijq value of 5.0 mM. The addition of CMP,CD or any of the other mono- or di-nucleotides did not inhibit the reaction. 

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