Cellodextrins

Cellulase The enzyme that cuts the linear chain of cellulose, a glucose polymer at 1-4-p-linkages into cellodextrins and glucose. 

CelMbrio gUvus. This organism grows well on cellobiose, cellodextrins, and cellulose, but less well on glucose conditions for optimized growth or enzyme production were not... 

Further progress can be expected in the area of selective inhibition and inactivat-iem of cellulases undesirable in xylanase preparations. There is a possibility of finding natural selective cellulase inhibitors or developing highly reactive derivatives of cello-biose and cellodextrins that inactivate cellulolytic enzymes. 

Steric Effects. Careful examination of scale models of the cellodextrins reveals that when C6 is positioned in a manner approximating the structure in / -methylcellobioside, the methylene protons are so disposed that they contribute significantly to creation of a hydrophobic protective environment for the adjacent glycosidic linkage. If, however,... 

Cellobiase can be measured by following the glucose production from cellobiose and cellodextrins, the saligenin from salicin, and the p-nitrophenol formation from its / -glucoside (2). 

Finally, the endo-/ -l,4-glucanase (Cx) can be assayed using amorphous cellulose, cellodextrins, or water-soluble derivatives by determination of the reducing sugars released or by viscosimetry. It is generally accepted that the release of reducing sugars is not a typical measure for the random action of endocellulases. 

As further evidence, we demonstrated by paper chromatography that hydrolysis products from cellooligosaccharides by Ex-1 are Gi and G2 from G3, and Gi, G2, and G3 from G5, but only G2 from G4, Ge, CMC, cellodextrine, and insoluble cellulose such as Avicel, swollen cellulose, absorbent cotton, and filter paper (Figures 13 and 14). However, G3 was formed from G6 when Ex-1 was incubated with a mixture of G6 and Gi. There is no indication that G6 was split by this cellulase into G3 plus G3, but rather that G2 produced from G6 was transferred immediately to Gi to form G3. The results are shown in Figure 15. 

These assays are for quick characterization of activity. Mode of action subsequently verified using pure component cellodextrins or cellulose. 

Figure 2. Hydrolysis of 14C-cellohexaose (G6) by BS and BI celluloses. The enzymes were purified to homogeneity (3) and incubated with pure uniformly-labeled cellohexaose as described in earlier tests with other celloaextrins (19). Reaction mixtures (0.3 mL) contained 1 mg substrate and cellulose (200 units) in 20mM sodium phosphate, pH 6.2, 0.03% sodium azide. They were incubated at 35°C and at intervals aliquots were removed and chromatographed. Cellodextrins with lower DP (Gt-G5) were located by radioautography and estimated by scintillation spectrometry (19).

Russell, J. B. 1985. Fermentation of cellodextrins by cellulolytic and noncellulolytic rumen bacteria. Applied and Environmental Microbiology 49 572-576. 

Shi, Y., and P. J. Weimer. 1996. Utilization of individual cellodextrins by three predominant ruminal cellulolytic bacteria. Applied Environmental Microbiology 62 1084-1088. 

Cellodextrin Reponses for DNS, Nelson-Somogyi (Nelson), and BCA Assays... 

Calculated as the ratio of the calibration sensitivities (or slope m) of the different cellodextrin standard curves to the glucose standard curve. Thus, a ratio of 1 is expected, theoretically, for a true reducing sugar assay, which has the same molar color yield for a series of saccharides. 

The novel, conserved aromatic residue F476, which is characteristic of subfamily IIIc CBMs, was particularly interesting in the sense that it did not form a hydrogen bond with the cellodextrin chain, and as a consequence its interaction with the substrate seems to be weak. Therefore, computational studies were conducted on this residue, and the results indicated that mutation of F476 to Y created a hydrogen bond between the CBM and the cellulose chain. This was likely to improve binding, and thus it was selected for site-directed mutagenesis. 

This enzyme, found in some bacteria which can metabolize cellulose, is theorized to be involved in the utilization of extracellular cellobiose produced by the action of cellulase (Kitaoka and Hayashi, 2002). This enzyme phosphoro-lyzes cellobiose but not cellotriose or anything larger. Cellooligosaccharides larger than cellotriose were phosphorolyzed by another phosphorylase called cellodextrin phosphorylase (EC 2.4.1.49). 

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