Cellulose cellulase

Humans do not produce the enzymes, called cellulases, necessary to digest cellulose. Bacteria possessing cellulase inhabit the digestive tracts of animals such as sheep, goats, and cows giving these animals the ability to digest cellulose. Cellulase bacteria also exist in the digestive systems of... 

Huang, A. A., "Kinetic Studies on Insoluble Cellulose-Cellulase System," Biotechnol. Bioeng. 17 (1975) 1421-1433. 

The colorimetric assays discussed herein are most commonly used in cellulose/cellulase studies to quantify the number of reducing sugars associated with the soluble phase (glucose, cellobiose, low-DP cellooli-... 

Index Entries Cellulose cellulase P-glucosidase Orpinomyces cellobiase. 

Starch -f Diastase Dextrin + Diastase Cellulose + Cellulase (Cytase)... 

In addition to ethanol from cellulose, cellulase enzymes play a minor role in the production of ethanol from corn. In this process, most of the glucose is from starch. Cellulase enzymes offer the opportunity to increase the glucose yield by hydrolyzing a portion of the cellulose to glucose, as well as decreasing the viscosity of the ground corn [25]. 

SSF is a process in which the production of ethanol from cellulosic materials is achieved by utilizing cellulose, cellulase, ethanol-producing microbes and nutrients in the same reactor. This process is desirable because the continuous removal of sugars by fermentative organisms alleviates end-product inhibition of enzyme hydrolysis of cellulose. The process is also simplified because only one reactor is used. The SSF process for ethanol production from cellulosic materials was reported by Blotkamp et al. [65] and was later tested on a pilot scale (for detail, see [66]). 

Cellulose Cellulase (Humicola insolens) Supercritical C02 Immobilized on ceramic membrane 45 °C, 101 bar [42]... 

Cellulose-Cellulase System. In Figure 10 are shown the accessibility curves of the cotton which had been swollen to different extents by phosphoric acid. The fiber saturation point, given by the amount of water inaccessible to a very large molecule, is seen to increase from 0.48 ml./ gram for cotton treated with water alone to 1.40 ml./gram for cotton swollen in 78.8% acid. The median pore size increased from 23 A. to 52 A. 

A Simplified Kinetic Approach to Cellulose-Cellulase System... 

Michaelis-Menten Mechanism Applied to Cellulose-cellulase System... 63... 

The nature of this inhibition has not been explained. Product inhibition in the case of dehydrogenation of dienedol and of hydrocortisone by cells of Septomyxa is also reported (Chen et al., 1962). For product inhibition of cellulose-cellulase system, no linearity is noticeable. Data (Ghose, 1969d) on high rate saccharification of cellulose at lower substrate concentrations are presented in Table 2 and Fig. 3. 

ES) = cellulose-cellulase complex concentration, n = number of moles of product,... 

If inhibition is caused by product, then I may be replaced by P and Ki by Kp, The inhibition mechanism may be described as formation of a complex between the enzyme and the inhibitor. This results in the partial loss of the compatibility to form the product In such a situation, therefore, the amount of product expected in the uninhibited reaction is always eater than that in the inhibited regardless of the nature of inhibition. The Eq. (18) should thus represent the model for competitive substrate or product inhibition. The rate of reaction should thus vary with either substrate concentration (in absence of inhibitor or product) or inhibitor (or product) concentration. It is not possible to evaluate the interdependence of the inhibition process between the three independent components the substrates, the products and known inhibitors. The Cellulose-cellulase system is one of competitive inhibition by two products of the process. This follows from the similarity of values of equilibrium constants, Kp for both cellobiose and glucose. The reciprocal plots for no inhibition, glucose and cellobiose inhibition based on the data of Table 4 are presented in Fig. 7. 

Webb, 1963), but, rather, is a more stable species. However, the ES complex does pass through a truly activated state in the course of coupling, and, in the case of a solid system, through a chain of such activated states. In the case of cellulose-cellulase system products (cellobiose or glucose) seem to be unbound to the enzyme but in others the products form complexes which are comparable to the ES complexes. Because cellulose is an insoluble substrate it has not been proven that there exists a product enzyme complex that is comparable to the enzyme substrate complex. The mechanism of the cellulose breakdown is an extremely complex system. 

These workers have also demonstrated the validity of the kinetic equations based on experimental data. However, the mechanism by which the enzyme-forming systems in derepressed cultures are not affected by repressing metabolites could not be explained. But, there exists a scope for verification of these models with the cellulose-cellulase system forming Q and C, complexes. 

A simplified Kinetic Approach to Cellulose-Cellulase System T. K. Ghose and K. Das, New Delhi (India)... 

Cellulose-cellulase incubation was done in 50 mM Na-acetate of pH 5 with 0.5 g/L bovine serum albumin (BSA to reduce nonspecific binding of cellulase on inner surface of reaction vessel) at 40 C. To study v dependence on [cellulase], 0.3 - 15 pM cellulase was reacted with 1.8 g/L cellulose. To study v... 

Cellulose-cellulase incubation was made at 25 C with 1 mL of 50 mM Na-acetate of pH 5, 0.8 - 62 pM cellulase, 1.8 g/L cellulose and 8 pM BSA in 1.2-mL Pierce ImmimoWare tubes. After 30 min, the supernatant was decanted, filtered (by 0.45 p Millipore Multi Screen-HV), and assayed by PASC hydrolysis activity for free cellulase. Langmuir adsorption equation, l/[E]adsorbed = l/([E]o - [E]) = l/(No tE]) + P/No (35), was then applied to calculate apparent capacity No (in mole/mole) and adsorption constant IC. 

E.A. Bayer, H. Chanzy, R. Lamed, and Y. Shoham, Cellulose, cellulases and cellulosomes, Curr. Opin. Struct. Biol, 8 (5), 548-557,1998. 

The general name given to an enzyme which breaks down cellulose. Cellulases are present in certain intestinal bacteria and in various other microorganisms such as those which inhabit the digestive tract of grazing animals (cattle, goats, and sheep). 

Bayer, EA Chanzy, H Lamed, R Shoham, Y. Cellulose, cellulases and cellulosomes. Current Opinion in Structural Biology, 1998, 8, 548-57. 

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