Acid cellulases

CellCept mycophenolic acid, cellulase [usan] is a concentrate of cellulose-splitting enzymes, isolated from Aspergillus niger. It is used as an adjunct DIGESTIVE AGENT. 

The use of acid cellulases are recommended for fast treatments and neutral cel-lulases for more severe treatments when marked effects are required [56,91 ]. Endo-enriched acid cellulase is found to be best for easily weekened fabrics such as 1 inen and viscose rayon. Standard whole acid cellulases are best for sturdy fabrics sucli as lyocell, modal rayon and heavy weight cotton [92]. 

The original cellulases used in denim washing were the crude enzymes of Trichoderma and Humicola, referred to as acid and neutral cellulase, respectively, based on the optimum pH range of use of the enzymes, which was pH 4 to 5 for the acid cellulase and 6 to 7 for the neutral cellulase. The Trichoderma cellulase, comprising the more complete set of EG and CBH components capable of the full hydrolysis of cellulose, works more quickly and is capable of a greater degree of abrasion and fading of the blue dye color than the Humicola cellulase. The Trichoderma cellulase also achieves certain desired finishes (appearances) that the Humicola cellulase does not. 

Most of the dyes used on Lyocell are more stable at acidic than alkaline pH, so this application has primarily been carried out using acidic cellulase from Trichoderma. The cellulase used can be the entire crude cellulase or modified cellulases with gentler action, depending on the size of the pills and the robustness of the fabric. 

Cellulose undergoes hydrolysis by cellulases under mild conditions, as compared to hydrolysis by inorganic or organic acids. Cellulases consist of core and... 

Figure 18.16 One-dlmenslonal NMR spectra, (a) H-NMR spectrum of ethanol. The NMR signals (chemical shifts) for all the hydrogen atoms In this small molecule are clearly separated from each other. In this spectrum the signal from the CH3 protons Is split Into three peaks and that from the CH2 protons Into four peaks close to each other, due to the experimental conditions, (b) H-NMR spectrum of a small protein, the C-terminal domain of a cellulase, comprising 36 amino acid residues. The NMR signals from many individual hydrogen atoms overlap and peaks are obtained that comprise signals from many hydrogen atoms. (Courtesy of Per Kraulis, Uppsala, from data published in Kraulis et al.. Biochemistry 28 7241-7257, 1989.)...

Cellulase enzyme complexes consist of three major types of proteins that synergistically catalyze the breakdown of a cellulosic substrate. Because the enzymes are strictly substrate-specific in their action, any change in the structure or accessibility of the substrate can have a considerable influence on the course of the hydrolysis reaction. A pretreatment method based on exposing cellulosic substrate to phosphoric acid solution [9] and addition of the nonionic... 

Dry bean curd refuse was used as the substrate in the lactic acid fermentation with simultaneous saccharification (SSF). The dry bean curd refuse was preliminarily sieved under a mesh size of 250 II m. It contained 12.3% water, 4.0% ash, 0.8% lipid, 29.3% protein, 53.6% carbohydrate, respectively, in weight basis. The cellulase derived from Aspergilltis niger with an enzymatic activity of 25,000 units/g (Tokyo Kasei Industry Inc.) was employed as the saccharification enzyme. 

Table 1 shows the dry weight of substrate, and amounts of HCl aqueous solution for pretreatment, cellulase and suspension broth for the lactic acid fermentation with ESS. The initially supplied amount of bean curd refuse in dry weight basis was changed from 10 to 150 g to examine the influence of substrate loading. The amount of cellulase was increased against initial substrate loading. And also, the amoimt of 0.1 mol/1 HCl was increased against... 

Fig. 1 Time couise of lactic acid yield and its concentration in SSF with or without pretreatment using 0.1 mol/l FICI with heating at 121 1 for 30 min. Famentation conditions 3TC, pH=5.0, initial load of bean curd refiise(BCR) 10 g, cellulase amount=l gin ILsuspension.

Figure 4. Content of galacturonic acid in the soiuble fraction after hydrolysis of AIS with polygalacturonases [a], with polygalacturonases and pectin methylesterase [b], with pectinases and cellulases [c].

Immunogold labeling with JIM S exhibited an identical labeling distribution for polygalacturonic acid as was obtained indirectly with the EPG EMSIL (inset of Fig. 1). Control experiments for labeling specificities obtained by the direct or indirect methods resulted in total elimination of specific labeling. The cellulase-gold probe heavily labeled the epidermal cell walls (Fig. 2). 

The traditional method of carbonising with sulphuric acid is environmentally undesirable and can easily lead to fibre damage. Hence it is not surprising that research has been directed towards alternatives in which enzymes are used to remove the cellulosic impurities from wool. Cellulases and lignases are mainly used but others have been proposed [116] ... 

As surfactants are often used in textile processing, it is important to note that anionic or cationic surfactants can inhibit the action of enzymes, as has been reported in the case of cellulases used for the treatment of cotton [140]. Dyes can also inhibit enzyme activity for example, Cl Direct Red 28 has been shown to have a much greater inhibitory effect than Cl Acid Orange 7 [141]. 

---