Alginic acids 3-eliminative degradation

Preiss and AshwelP reported the 8-eliminative degradation of alginic acid by means of a purified, cell-free extract of an adapted pseudomonad. In addition to 64, oligosaccharides were obtained that contained the characteristic, terminally linked, unsaturated deoxyhexopyranuronate residue, as shown in 65. It was, however, not proved whether the n-... 

Hence, the stereochemistry of the 8-eliminative degradation of alginic acid seems to be similar to that of the heteropolysaccharide chain of heparin. As already described, in tbe latter 8-eliminative degradation, both the D-glucopyranuronate and the L-idopyranuronate, possessing the same stereochemical disposition of the groups on C-5 and C-4 of the ring, are involved. 

On reduction with a specific dehydrogenase, the unsaturated, /8-eliminative, degradation products 66 and 67 obtained from alginic acid give 3-deoxy-D-erythro-hexulosonate (72). Ashwell and coworkers ... 

---