13-6-Glucanase

Genetic manipulation or cloning offers many possibiUties and perhaps there will be yeast strains especially designed for special beers, ie, types, which are usehil because of low diacetyl formation, high—low ester formation, and insensitivity to pressure or high fermentation temperatures or extracellular enzymatic abiUties (P-glucanases). 

The minor content of impurities found ia the starch slurry are connected to the starch granules themselves. To faciUtate the purification of the starch duriag filtration, ceUulases, pentosanases, glucanases, proteases, and pectinases are sometimes used. Wheat starch is known to form precipitates or hazes that are difficult to filter. Arabiaoxylan, pentosanes, andlysophosphoHpids are claimed to be responsible for this problem (73). 

Fig. 14 Effect of the molecular weight of tamarind seed xyloglucan depolymerized by ( ) 7-irradiation, ( ) ultrasonication, and ( ) endo-glucanase treatment on the production of various cytokines (Tumor necrosis factor a, TNE-a Interleukin 8, IL-8 Interleukin 10, IL-10 and Interleukin 12, IL-12) in HaCaT cells (Immortalized keratinocytes line) [301]...

Hehre and coworkers showed that beta amylase from sweet potatoes, an inverting, a-specific exo-(l 4)-glucanase, catalyzes the hydrolysis of jS-maltosyl fluoride with complex kinetics which indicated the participation of two substrate molecules in the release of fluoride ion. Furthermore, the reaction was strongly accelerated by the addition of methyl ) -maltoside. Hydrolysis of a-maltosyl fluoride, on the other hand, obeyed Michaelis-Menten kinetics. The main product with both a- and yj-maltosyl fluoride was )S-maltose. The results with )3-maltosyl fluoride were interpreted by the assumption of a glycosylation reaction preceding hydrolysis by which a malto-tetraoside is formed by the replacement of fluoride ion by a second substrate molecule or added methyl -maltoside (see Scheme 5). 

However, if theoritically, the combination of pectinases to cellobiohydrolases plus endo-glucanases should release more than 80% of all polysaccharides from the cell walls (according to Voragen and al. [4]), in industrial conditions, we arrive almost at this level of degradation but only for the pectin. Commercial enzymes preparations contain pectinases, hemicellulases and cellulases. 

Pectin releasing enzyme mix RGase A + RGAE + galactanase + arabinanase + a-arabino-furonasidase + endo-glucanase III + protease II. 

Preteatment with pectinases improves meehanieal debarking of wood significantly. In addition to polygalacturonase, enzymes hydrolysing the neutral polymers in cambial tissue (arabinanase, galactanase, and glucanase) are needed for effective solubilization of spruce cambium. 

IV. PARASITISM. Lysis by hydrolytic enzymes excreted by microorganisms is a well-known feature of mycoparasitism. Chitinase and P-l,3 glucanase (laminarase) are particularly important enzymes secreted by fungal mycoparasites capable of degrading the fungal cell wall components, chitin, and P-1,3 glucan (131-134). 

Many rhizobacteria are classified as chitinolytic and, for example, Serratki marsescens, which excretes chitinase, was found to be an effective biocontrol agent against Sclerotium rolfsii (135). Similarly, Aeromonas caviae was found to reduce disease caused by Rhizoctonia solani, Fusarium oxysporuin, and Sclerotium rolfsii (136). There is also evidence to support the role of P-l,3 glucanase in biocontrol of soil-borne plant pathogens (137). 

A list of entrapped enzymes is given in Table 3.2. There are two endo-l,3-P-D-glucanases from marine mollusks Spisula sacchalinensis and Ch. albidus and a-D-galactosidase from marine bacterium Pseudoalteromonas sp. MM 701. They were selected for immobilization for the following reasons ... 

Endo-1,3-P-D-glucanase Le is a highly labile enzyme. It is especially sensitive to temperature, denaturating at 25 °C. The common approaches were unsuitable for its immobilization. 

Fig. 3.10 Relative activities of endo-l,3-P-D-glucanase L V in aqueous solution (1) and in the immobilized state (2) as well as immobilized endo-l,3-P-D-glucanase L0 (3) vs. the time of testing. The enzyme entrapment was performed as described in Refs. [55,56], The silica matrix...

The decreased denaturating action of the precursor and procedure enables one to immobilize reduced amounts of biomaterial. It was demonstrated in Ref. [55] that biocatalysts prepared by entrapping endo-l,3-P-D-glucanase and a-D-galactosidasc in amounts comparable to that in living cells had a reasonable level of activity. When the TEOS is applied, the enzyme content in silica matrix can be up to 20-30 wt.% to counterbalance losses due to denaturation [50]. 

Shchipunov, Yu.A., Burtseva, Yu.V., Karpenko, T.Yu., Shevchenko, N.M. and Zvyagintseva, T.N. (2006) Highly efficient immobilization of endo-l,3-P-D-glucanases (laminarinases) from marine mollusks in novel hybrid polysaccharide silica nanocomposites with regulated composition. Journal of Molecular Catalysis B-Enzymatic, 40, 16-23. 

M. Faijes, X. Perez, O. Perez, and A. Planas, Glycosynthase activity of Bacillus licheniformis 1,3-1,4-beta-glucanase mutants Specificity, kinetics, and mechanism, Biochemistry, 42 (2003) 13304—13318. 

There are few reports of barley used for the production of recombinant proteins but some of those reports show high expression levels which, due to the low producer price of barley, could make this a viable production crop. In early reports, recombinant glucanase and xylanase were expressed at very low levels (0.004%) [79,80] but as stated above, a recombinant diagnostic antibody (SimpliRED, for the detection of HIV) has been expressed at levels exceeding 150 pg g-1 [15], and a recombinant cel-lulase enzyme was expressed at levels exceeding 1.5% total seed protein [16]. 

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