Phosphoric acid swollen cellulose

Figure 10. Product distribution from the incubation of enzymes (produced by T. reesei QM 9414 in response to sophorose) with phosphoric-acid swollen cellulose (PSC). Incubation time in this figure indicates the length of incubation of T. reesei mycelia in the presence of ImM sophorose. Enzymes produced at those times were incubated with PSC for 15 hr, and the products analyzed by HPLC (18/...

PMOs are supposed to be active only on (semi)ctystalline polysaccharides and not on short soluble oligosaccharides (DP 2-5). Harris et al. tried a whole variety of substrates and concluded that mixed substrates like PCS (pre-treated corn stover) generate higher activities than pure cellulose substrates like Avicel (microcrystalline cellulose) or PASC (phosphoric acid swollen cellulose).However, hemicellulose substrates do not tend to be more efficiently degraded by PMO addition. The first successful experiments with real pre-treated biomass, namely pre-treated spruce, were recently performed. ... 

Endoglucanases hydrolyze 3-l,4-glycosidic linkages randomly. They do not attack cellobiose but hydrolyze cellodextrins, phosphoric-acid swollen cellulose and substituted celluloses such as carboxymethyl (CM)- and hydroxyethyl (HE)-cellulose. Trichoderma seems to secrete a number of respective enzymes into the medium, of which two (EG I, EG III) have been the subject of a more detailed investigation. It should be noted that some confusion has arisen in the past from the fact that EG III was termed EG II by several authors from the US. However, this has been overcome now. 

Cotton linters were swollen to an increasing extent by means of phosphoric acid of increasing concentration, Using a number of simple sugars plus a series of dextran molecules ranging in M.W. from 180 to 2,4 X 107 and diameter from 8 to 1600 A, it was possible to measure the pore volume and calculate the surface area within the swollen fibres accessible to all the molecules within this range. The substrates reacted with a commercial cellulose enzyme preparation, and the initial rate of reaction was compared with the accessibility of the substrate to molecules of various sizes. There was found to be a linear relationship between the initial reaction rate and the surface area within the cellulose gel which was accessible to a molecule of 40 A, diameter. 

Cellulose-Cellulase System. In Figure 10 are shown the accessibility curves of the cotton which had been swollen to different extents by phosphoric acid. The fiber saturation point, given by the amount of water inaccessible to a very large molecule, is seen to increase from 0.48 ml./ gram for cotton treated with water alone to 1.40 ml./gram for cotton swollen in 78.8% acid. The median pore size increased from 23 A. to 52 A. 

Water-soluble cellulose phosphate of high viscosity and a D.S. was prepared by Katsuura et al. by treating pulp, pre-swollen with zinc chloride, with phosphoric acid in molten urea at 150°C (42). 

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