Glucomannan polymers, molecular weight

A number of plant [106, 178-183] and algal [64, 176] polysaccharides have structures based on a P(l-4)mannan main chain - P(l-4)mannan, a(l-6)galacto-P(l-4)-D-mannan and the related P(l-4)-D-glucomannan and galacto-P(l-4)glucomannan. They serve as cell wall structural material and as carbohydrate reserve polymers. An unbranched P(l-2) mannan of low molecular weight has been reported from the insect flagellate Herpetomonas samuelpessoai [184]. 

A final and unexpected polymorphism parameter is found in the molecular weight of the sample to be crystallized. This is in particular described in the case of mannan and glucomannan polymers(4,8) where crystals of mannan I are usually obtained with low degree of polymerization (DP) material, whereas only mannan II is found when higher DP are recrystallized. 

A similarity can be established between the polymorphism of mannan and that of cellulose, as with both polysaccharides, one observes a molecular weight influence on the polymorphism, even though this influence is more pronounced in the case of mannan than in the case of oe llulose. It was shown that with mannan and glucomannan polymers, the mannan I structure was obtained more easily with low molecular weight material, whereas mannan II corresponded to higher molecular weight (4,8). A close resemblance... 

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