Of cellobiose

Strong acids completely hydrolyse cellulose to glucose very mild hydrolysis gives hydrocelluloses with shorter chains and lower viscosity and tensile strength. Under special conditions a large yield of cellobiose is obtained. 

Show the product you would obtain from the reaction of cellobiose with the following reagents ... 

Interproton distances of 0-ceIIobiose (see Ref. 49) error 0.01 A. Interproton distances of 1,6-anhydro- -D-glucopyranose (see Ref. 49) error 0.01 A. Interproton distances of -cellobiose octaacetate (see Ref. 49) error 0.05 A. Interproton distances of 2,3,4-tri-0-acetyl-l,6-anhydro- -D-glucopyranose (see Ref. 49) error 0.05 A. Error calculations based on the errors of the measured quantities in Eqs. 18 and 21. Interproton distances calculated from the relaxation parameters of the methylene protons. 

Figure 4.2 Conformation map of cellobiose. Enclosed area defines allowed conformations in which there are no major conformational restrictions arising from interactions between non-bonded atoms.

SONG w o, BEECHER G R and eitenmiller R R (2000), Modern Analytical Methodologies In Fat- and Water-soluble Vitamins. Chichester, Wiley. sprenger c, galensa r and jensen d (1999), Simultaneous determination of cellobiose, maltose and maltotriose in fruit juices by high-performance liquid chromatography with biosensor detection , Dtsch Lebensm Rundsch, 95, 499-504. 

A marked difference in the product pattern has been reported for the treatment of cellobiose with either NaOH or NaHCOs. The formation of 3-deoxy-2-0-(hydroxymethyl)pentonic acids (52) from cellobiose is less important in sodium hydrogencarbonate solution than in sodium hydroxide, while the relative amounts of 2-deoxytetronic, 3-deoxypentonic, and 3,4-dideoxypentonic acids are much larger. 

Hydrolysis of delignified wheat straw up to 90% was obtained in 96 hours with the cellulase system produced in SSF with wheat straw. It took only 72 hours to obtain over 90% hydrolysis of wheat straw with cellulase system produced with SSF on Pro-cell (Table VII). It is interesting to note that the quantity of cellobiose in the hydrolysate obtained with the cellulase system produced on Pro-cell was higher than that of the cellulase system produced on wheat straw. This is consistent with the observation that cellulase system produced on Pro-cell had a lower ratio of FP cellulase )3-glucosidase (1 0.77) as compared to that produced on wheat straw (1 1.2). However, this cellulase system had a faster hydrolysis rate it took only 72 hours to obtain over 90% hydrolysis. This might be related to cotton hydrolyzing activity of this cellulase system (Table V). 

Figure 6 depicts the relationship between the specific enthalpy of denaturation measured for CBH I at each of the pH values used in this study, and the of the principal peak at that pH. The strai t line represents a least>squares best fit to the four experimental data points and the empirically derived intersection point (Reference 2, see Discussion) in the upper right comer. All the values determined in the absence of cellobiose, both those at pH values at which the denaturation exhibits a substantial degree of overall reversibility, and those at which the overall process is completefy irreversible, are in reasonably good agreement with the linear relationship. 

Stabilization by Cellobiose. Figure 6 also shows that when different concentrations of the competitive inhibitor cellobiose are present in the DSC samples at pH 4.8 and pH 8.34, the principal denaturation peaks are displaced to higher temperatures, as indicated by the higher T values shown. The AH values, however, do not follow the trend of increasing enthalpy with increasing that is seen for the data in the absence of cellobiose. Instead, the peak areas in the presence of cellobiose are essentially the same as for the peaks appearing at lower temperatures at these pH values in the absence of cellobiose. 

Figure 6. Specific enthalpy of denaturation for native CBH I, plotted as a function of the overall observed as the enzyme molecule is progressively destabilized by increasing the pH. Dot-centered circles represent the specific enthalpy in the absence of cellobiose the straight line is a linear least-squares best fit to these data points, plus the empirically derived intersection point (reference 2, see Discussion) represented by the crossed circle at upper right. The squares represent enthalpies measured at pH 4.80 and pH 8.34 in the presence of the indicated concentrations of cellobiose.

What we observe, both at the pH value (4.80) chosen to be near the activity optimum for the enzyme and at the value (8.34) chosen to produce substantial pH-stress, is that in the presence of cellobiose the enzyme has marked higher T values, but the overall shape of the denaturation envelope is very similar to diat observed in the absence of the inhibitor. In addition, the overall AH° values in the presence of even quite high concentrations of inhibitor are very close to those observed at lower temperatures in the absence of inhibitor, rather than resembling the values that the linear regression of Figure 6 would seem to imply for denaturation processes at these elevated temperatures. 

A summary of the key information has been compiled on the anaerobic and aerobic bacteria discussed above. Comparison of the substrates for growth of these organisms (Table I) show that all utilize cellobiose and various forms of cellulose. The two species belonging to Bacteroides have different specificity for substrates, while those for Ruminococcus, Cellulomonas and Thermomonospora were the same. Table I also allows comparison of the behavior of the 13 species of cellulolytic bacteria toward cellobiose. More variability is noted in this regard and no correlation between induction/repression can be made with the mechanism of cellobiose degradation. 

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