Heptoses studies

Recent work in the authors laboratory has been directed at the definitive elucidation of structure of the KDO-trisaccharide by n.m.r.-spectroscopic methods. For this purpose, the LPS from the heptose-less, jS. minnesota R 595 mutant is being studied, which has been reported (6 to contain, aside from lipid A, only three KDO residues. The preparation of a homogeneous pseudo-tetrasaccharide, containing besides the three KDO re-... 

The cyclodehydration of 18 to the anhydroalditol derivative 19 has been explained as an attack by the 6-hydroxyl group on the double bond. Studies by Hall et al.59 of acyclic sulfones formed from two heptose dithioacetals epimeric at C-2 revealed their ready conversion in hot water into a common... 

Kondakova, A.N., Ho, N., Bystrova, O.V., Shashkov, A.S., Lindner, B., Creuzenet, C., Knirel, Y.A. Structural studies of the O-antigens of Yersinia pseudotuberculosis 0 2a and mutants thereof with impaired 6-deoxy-D-manno-heptose biosynthesis pathway. Carbohydr Res 343 (2008b) 1383-1389. 

This work was followed by the detection of an aldoheptose in Escherichia coli products and the subsequent isolation of jj-glycero-i>-manno-heptoee by Weidel, again in connection with phage-receptor studies. The sugar was obtained from the lipocarbohydrate fraction of Escherichia coli B cell-membranes and was isolated, after acid hydrolysis, on a cellulose-powder column. In this case, sufficient of the product was obtained to show that the diethyl dithioacetal and its hexaacetate had equal but opposite optical rotations, as compared with those of the same derivatives prepared from authentic D-glyc o-n-manno-heptose. 

Roe and Hudson demonstrated that D-mannoheptulose is physiologically available to the rabbit, which has a high tolerance for this heptose. This prompted Hiatt and coworkers to study the capacity of the corresponding polyol, D-volemitol, which occurs in mushrooms and Primula species, as a precursor of glycogen in the liver of the white rat. Through a series of feeding experiments, Hiatt et al. concluded that... 

A non-specific bacterial acid phosphatase from Shigella flexneri (PhoN-Sf) has been screened for regioselective phosphorylation of primary alcohol(s) of more than 20 different cyclic and acyclic monosaccharides using pyrophosphate as the phosphate donor (O Scheme 61) [368]. These studies have shown that PhoN-Sf is capable of phosphorylating a range of hexoses (D-glucose epimers, glycosides, and C-2 derivatives), pentoses, heptoses, ketoses, and acyclic carbohydrates. 

Despite their quite recent history of investigation, two key enzymes of heptose metabolism have been purified and characterized biochemically, which open opportunities for structural studies [156]. 

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