Cotton, cellobiose from

We have spent some time investigating possible heterogeneity in the Ci components of F. solani, T. koningii, and P. funiculosum. This has been done by testing for both Ci activity (defined as the enzyme that acts in synergism with the Cx enzymes to solubilize cotton cellulose or other crystalline cellulose) and cellobiohydrolase (release of cellobiose from H3P04-swollen cellulose) during different fractionation studies on the various Ci components. 

Cellulose is the principal structural component of vegetable matter. Wood is 30-40% cellulose, cotton over 90%. Photosynthesis in plants is responsible for the formation of 109 tons per year of cellulose. Structurally, cellulose is a polysaccharide composed of several thousand D-glucose units joined by (3(l,4)-glycosidic linkages (Figure 25.8). Complete hydrolysis of all the glycosidic bonds of cellulose yields D-glucose. The disaccharide fraction that results from partial hydrolysis is cellobiose. 

Karl-Erik Eriksson (42) reported that he had prepared an enzyme from Chrysosporium lignorum which, when combined with each of three CM-cellulase enzymes, increased the hydrolysis rate of cotton tenfold. When he incubated this enzyme, which he believed to be of the Ci type, with cellohexaose and observed cellobiose as the only product, he concluded that it was an exo-glucanase which split off cellobiose units. Later (27) Eriksson and Rzedowski reported that the three CM-cellulase enzymes from C. lignorum contained 13, 10, and 7% carbohydrate and catalyzed the hydrolysis of cotton and cellodextrins to produce cellobiose and glucose in the approximate ratio of 3 1. 

In 1968 Nisizawas laboratory (55) purified three cellulase components from Meicelase, which is a commercial cellulase from Trichoderma viride. These three components—Cellulases II, III, and IV—contained 16.8, 15.6, and 10.4% carbohydrate, respectively, and were active in hydrolyzing cellooligosaccharides, CM-cellulose, and cotton. They were inactive toward cellobiose and p-nitrophenyl-yS-D-glucoside. 

In 1972 Ogawa and Toyama (56) purified three components— A-I-a, A-I-b, and A-II-1—which were adsorbed on a gauze column during purification from Cellulase Onozuka P1500, a commercial preparation of T. viride cellulase. These three components had molecular weights of 32,000, 48,000, and 48,000 as determined by gel filtration and contained 7-16% carbohydrate. Each is reported to carry out the random hydrolysis of CM-cellulose and to degrade hydrocellulose (Avicel) and cellooligosaccharides except for cellobiose. The order of reactivity toward either cotton or Avicel was A-II-1 > A-I-b > A-I-a. The proteins adsorbed on cellulose comprised 38% of the total cellulase protein. 

The Ci, Cx concept has recently been extensively studied by a number of workers (16,23, 24, 27, 31, 32,46), for two species of Trichoderma, namely T. viride and T. koningi. It was shown that cell-free culture solutions of these fungi were able to solubilize cotton fibers. The solubilization of cotton fibers is also a way of measuring the activity of the Ci enzyme. In the most recent of these publications (46) Selby and Maitland were able to isolate the Ci enzyme from culture filtrates of T. viride. The enzyme was shown not to act upon cellobiose or carboxymethyl cellulose and to lose its ability to solubilize cotton in the absence of the Cx component. The mechanism of action of the Ci enzyme is thus still obscure although many different hypotheses have been presented (34). 

Cellulose is obtained from wood, cotton, and other plants and is a natural linear polymer. The basic structural repeating unit for cellulose is the cellobiose unit, represented by the following structure ... 

Morphologically cotton cellulose is highly crystalline. Estimations of the extent of crystallinity vary, depending upon the measurement method used, from 75% to 95%. This configuration is almost a rectangular parallelepiped containing a cellobiose unit in each corner, with a central cellobiose unit in the center, antiparallel to the other four. 

Cellulase from Aspergillus niger and Stachy-botrysatra Hydrolysis of cellulose to cellobiose Aid to extraction of pharmaceutically active principles removal of cellulose from food for special diets softening of cotton. 

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