Oxidative enzymes, cellulose

The question of the involvement of oxidative enzymes in the breakdown of cellulose has been raised periodically, but now there is definite evidence that such enzymes occur in some culture filtrates. This was established by Eriksson and his colleagues (2) when they found that concentrated cell-free filtrates of the fungi S. pulverulentum, Polyporus adustus, Myrothecium verrucaria, and T. viride solubilized cellulose at a slower rate under anaerobic than under aerobic conditions. 

Figure 6. Both hydrolytic and oxidative enzymes participate in cellulose decomposition by the white-rot fungus Phanerochaete chrysosporium Burds. Hydrolytic enzymes i, endo-1 - - I ucanases 2, exo-1,4- -glucanase and 3, -glucosidase. Oxidative enzymes 4, glucose oxidase, 5, cMlobiose oxidise and 6, cellobiose quinone oxidoreductase. Adapted from Reference 23,...

Cellobiose Oxidases. — A recently discovered oxidative enzyme of importance in in vitro cellulose degradation seems to be a cellobiose oxidase. The contribution of this enzyme to the degradation has been discussed in a review of cellulose enzymolysis. 

Active enzymes were encapsulated into a sol-gel matrix for the first time in 1990 719 About 60 different types of hybrid bioceramic materials with inotganic matrices made from silicon, titanium, and zirconium oxides Ti02-cellulose composites etc. were described. Recentiy, bioceramic sensors, solid electrolytes, electrochemical biosensors, etc. have been surveyed in a review. The moderate temperatures and mild hydrolytic and polymerization conditions in sol-gel reactions of alkoxides make it possible to trap proteins during matrix formation. This prevent proteins denaturation. The high stability of the trapped biomolecules, the inertness, the large specific surface, the porosity, and the optical transparency of the matrix facilitate use of sol-gel immobilization. The principal approaches ate considered below. 

The binding of 2-acetamido-2-deoxy-a- and -jS-o-glucopyranoses to hen egg-white lysozyme with its tryptophan-62 residue oxidized has been investigated. It appears that the a-anomer binds at the subsite in two mutually exclusive orientations, one of which corresponds to that adopted by the /S-anomer. The oxidized enzyme has been purified by affinity chromatography on a chitin-coated cellulose, and its activities towards glycolchitin and bacterial cells were examined. The activities of other derivatives of the enzyme were also examined. 

Y. Kurokawa, T. Sano, H. Ohta, and Y. Nakagawa, Immobilization of enzyme onto cellulose-titanium oxide composite fiber. Biotech. Bioenerg. 42, 394—397 (1993). 

Cathodic Protection method where a more active metal is connected to a metal structure such as a tank or a ship protecting the structure because the active metal is oxidized rather than the structure Cation a positively charged ion Cellulase a group of enzymes that hydrolyze cellulose... 

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