Galactans, molecular weight

Galactans are found in association with other hemicelluloses in deciduous and coniferous woods, certain seeds and pectins. It is very difficult to obtain the pure polysaccharide. Not much is known of the detailed structure of these molecules,61 and few molecular weight measurements have been carried out. 

The above structure is very different from that of the galactan associated with pectin in the seeds of Lupinus albus. This was shown to have a chain-length of 120 units.64 As no molecular weight measurements have been carried out on this material, it is not known whether the molecule is linear or branched. 

The second class comprises conventional solids, defined by a chemical formula, but whose property requirements are very minimal. In this class we included lignin, cellulose, mannan, galactan, xylan, arabinan and the biomass. The properties specified in the database include molecular weight, heat of formation, solid molar volume, and solid heat capacity. 

If these materials were pure polymerized di-nitric acid esters of galacturonic acid anhydride, the maximum molecular weight would corre.spond to a chain length of approximatelj" 740 units. Since, however, admixed arabans and galactans are present, the chain length must be less than 740 units. 

Zuniga, E. A., Matsuhiro, B., and Mejias, E. (2006). Preparation of a low-molecular weight fraction by free radical depolymerization of the sulfated galactan from Schizymenia hinderi (Gigartinales, Rhodophyta) and its anticoagulant activity. Carhohydr. Polym. 66,208-215. 

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