Xylanases

Xylanases are synthesized by fungi, bacteria, marine algae, insects, seeds, etc. but the principal source of commercial xylanases is filamentous fungi. The fungi secrete xylanase into the extracellular medium along with several accessory xylanolytic 

Goals in the development of a recombinant laccase are to obtain a laccase variant with increased reduction potential, thermal stability, and pH range and to identify new mediators and processes that improve the effectiveness of laccase in the degradation of lignin. Also, improved recombinant laccases and improved laccase mediators should result in higher strength fiber compared to conventional bleaching. Other potential applications of laccase include treatment of fabrics and catalysis of polymer synthesis. 

Xylanase is an enzyme that selectively hydrolyzes xylan to yield xylose as a product. Xylanase does not remove lignin, but it allows it to be more easily removed in 

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Bulk Enzymes. Enzymes such as proteases, amylases, glucose isomerases, and rennin are used in food processing. Similarly proteases and Hpases are used in detergents. CeUulases and xylanases are used in the paper pulp industry. The genes for most of the enzymes used in the various commercial processes have been cloned and overexpressed. Rennin (chymosin) produced from E. coli and A. nigerhas been approved by FDA for use in the dairy industry. 

D. J. Senior,]. Hamilton, R. L. Bernier, and]. P. Manoir, "Reduction ia Chlorine Use During Bleaching of Kraft Pulps EoUowiag Xylanase... 

Xylanase (from Streptomyces lividans) [37278-89-0] Mr 43,000 [EC 3.2.1.8]. Purified by anion-exchange chromatography on an Accell QMA column and finally by HPLC using a ProteinPak DEAE 5PW anion-exchange column. Solutions were stored frozen at -70°. [Morosoli et al. Biochem J 239 587 79S6 Wong et al. Microbiol Rev 52 305 1988.]... 

Partial etherification of the beech wood MGX with p-carboxybenzyl bromide in aqueous alkali yielded fully water-soluble xylan ethers with DS up to 0.25 without significant depolymerization the Mw determined by sedimentation velocity was 27 000 g/mol [400,401]. By combination of endo- 6-xylanase digestion and various ID- and 2D-NMR techniques, the distribution of the substituents was suggested to be blockwise rather than uniform. The derivatives exhibited remarkable emulsifying and protein foam-stabilizing activi-... 

Voragen AGJ, Gruppen H, Verbruggen MA, Vietor RJ (1992) In VisserJ, Beld-mann G, Kusters van Someren AS, Voragen AGJ (eds) Xylans and Xylanases. Elseveir Science, Amsterdam, p. 51... 

Protein isolation with affinity precipitation has been discussed in detail by Mattiasson and co-workers (see, e.g. Galaev and Mattiassion, 1997) and they have provided an exhaustive tabulation. Polymers varied from alginate.s/chitosan to dextran to NIPAM. Examples of the used proteins are from trypsin, p-glucosidase, xylanase, alkaline protease, etc. It is remarkable that affinity precipitation can sometimes give results comparable to affinity chromatography. 

Sinlac M. and Choct M. (2000). Xylanase supplementation affects the caecal microflora of broilers . Austral Poult Sci Symp, 12, 209. 

Stemmer M, Gerzabek MH, Kandeler E (1999) Invertase and xylanase activity of bulk soil and particle-size fractions during maize straw decomposition. Soil Biol Biochem 31 9-18... 

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]. 

EnZone [Enzyme ozone] A pulp bleaching process using the enzyme xylanase in combination with oxygen, ozone, and hydrogen peroxide. Invented by K.-E. L. Eriksson at the University of Georgia and piloted in 1998. 

Brown-rot fungus (isolate MAD-698) was grown on sterile 12 mm glass slips placed on the surface of 2% (w/v) malt agar removed when about 50% covered were localized using colloidal gold labeled monoclonal antibodies to the B-l, 4-xylanase fraction of P. placenta-, enzymes were localized on the hyphal surface... 

FIG. 1 Effect of different enzymes or combination of enzymes (cellulases, xylanases, cellobiases, 3-glucanases, and proteases) on starch yield in the conventional corn wet milling process. 

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