Digalacturonic acid

Derivatives of the digalacturonic acid units /l-D-GalpA-(l — 2)-D-GalpA, /l-D-GalpA-(l -> 3)-D-GalpA, and /5-D-Gal/ A-(l 4)-D-GalpA have been prepared.187... 

The Pseudomonas enzyme diflFered from the Erwinia enzyme in that saturated oligogalacturonides were degraded as rapidly as the corresponding unsaturated uronides activity was maximal with tetramers, follower by trimer, dimer, and then polymer and Ca stimulated activity. With a purified enzyme preparation the reaction product from unsaturated digalacturonic acid was 4-deoxy-5-keto-D-glucuronic acid with crude extract a mixture of this acid and 4-deoxy-5-keto-D-fructuronic acid resulted. 

Okamoto et al, (46, 47, 48, 49) isolated a polygalacturonate lyase from Erwinia aroideae. Since an acid soluble pectic acid was degraded to unsaturated digalacturonic acid and continually shortening chains, these authors also concluded that the attack was from the reducing end. 

C. Gouvion, K. Mazeau, A. Heyraud, F.R. Taravel and Tvaroska I. Conformational study of digalacturonic acid and sodium digalacturonate in solution. Carbohydr. Res. 261 (1994) 187. 

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