The effect of cellulase treatments on the rheology of carboxymethyl cellulose (CMC) solutions was... more The effect of cellulase treatments on the rheology of carboxymethyl cellulose (CMC) solutions was studied using a rotational viscometer. The rheological behaviors of CMC solutions of different molecular mass and degrees of substitution where studied as a function of time after various treatments. These solutions were subjected to active and heat-denatured cellulase, a cationic polyelectrolyte (C-PAM), as well as different shear rates. A complex protein-polymer interaction was observed, leading to a potential error source in the measurement of enzymatic activity by changes in the intrinsic viscosity. The interaction was termed a polymeric effect and defined as a reduction in viscosity of the substrate solution without significant formation of reducing sugars from enzymatic hydrolysis. The cause of the reduction in viscosity appears to be related to the interaction between the enzymes as amphipathic particles and the soluble CMC. Thus, the polymeric effect may cause a considerable exp...
Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry
ethylidene]<t-D-glucopyranose (C,6H2401o) crystallizes in the monoclinic space group, P21, with Z... more ethylidene]<t-D-glucopyranose (C,6H2401o) crystallizes in the monoclinic space group, P21, with Z= 2 and cell parameters a= 7-649 (4), b = 14.465 (5), c = 8.213 (3) ,~, and ,8=96.26 (7) ° at the experimental temperature of about -193°C. The structure was solved using Patterson search and tangent formula methods. Block-diagonal least-squares refinement, with fixed hydrogen parameters, resulted in a final R index of 0.068 for 1680 observed reflections. The diastereoisomer investigated, which exhibits a p.m.r, methyl singlet at 6 1-71 p.p.m. (CDCI0, has the (S)-configuration at the dioxolane-2-carbon atom, i.e., the ethoxy substituent is trans or exo to the pyranoid ring. The dioxolane ring has an envelope conformation, with 0(2) deviating 0.46 A, from the plane of the other four atoms toward the glucose-ring side of the plane. There are considerable structural differences in the O(1) and 0(2) sides of the dioxolane ring. The pyranoid ring approximates a skew (3S5) conformation with some additional flattening in the vicinity of C(I) and C(2) due to the presence of the dioxolane ring. The solution p.m.r, data are consistent with the pyranoid-ring conformation found in the crystal structure.
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