Native cellulose solubilization

The key role of C6 in stabilizing the native cellulose lattice is supported by recent findings concerning the mechanism of action of the dimethyl-sulfoxide-paraformaldehyde solvent system, which is quite effective in solubilizing even the most crystalline of celluloses. The crucial step in the mechanism proposed for the action of this system is substitution of a methylol group on the primary hydroxyl at the C6 carbon (26, 27). 

Synergism Between Enzymes Involved in the Solubilization of Native Cellulose... 

Hphe study of the synergism shown by enzymes of the cellulase complex in solubilizing highly ordered native cellulose has now progressed to a stage where it is possible to state with some certainty the principal enzyme components involved. Not everyone agrees, however. 

As currently understood, cell-free enzyme preparations that can solubilize native cellulose contain at least two types of enzyme, so-called Ci and Cx (I). A third enzyme, a / -glucosidase or cellobiase, is normally,... 

The degree of polymerization (DP) of native celluloses depends on the source, and is not well established. Indeed, the combination of procedures required to isolate, purify, and solubilize cellulose generally causes scission of the chains. The DP values obtained are therefore minimal and depend on the methods used. Values of DP ranging from hundreds to several tens of thousands have been reported.For the same reasons the distribution of chain lengths of cellulose is not well established. Nonetheless, some authors suggest that the molecular mass distribution must be homogeneous for a cellulose of a given source. ... 

The high crystallinity of native celluloses, the extensive inter-and intramolecular hydrogen bonding even in the amorphous areas prevent entry of water, and other polar solvents such as dimethyl sulfoxide, and the interaction of water, etc., with the OH s groups on the cellulose molecule, hindering solubilization. 

The bacterial cellulose synthase from Acetobacter xylinum can be solubilized with detergents, and the resulting enzyme generates characteristic 1.7 ran cellulose fibrils (Fig. 20-4) from UDP-glucose.125/127-129 These are similar, but not identical, to the fibrils of cellulose I produced by intact bacteria.125 130 Each native fibril appears as a left-handed helix which may contain about nine parallel chains in a crystalline array. Three of these helices appear to coil together (Fig. 20-4) to form a larger 3.7-nm left-handed helical fibril. Similar fibrils are formed by plants. In both... 

Kleman-Leyer, K. M., Siika-Aho, M., Teeri, T. T., and Kirk, T. K. 1996. The Cellulases Endoglucanase I and Cellobiohydrolase II of Trichoderma Reesei act synergistically to solubilize native cotton cellulose but not to decrease its moleculare size. Appl. Environ. Microbiol., 62,2883-2887. 

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