Topic
Xylanase
About: Xylanase is a research topic. Over the lifetime, 7099 publications have been published within this topic receiving 163793 citations.
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TL;DR: Patterns of hydrolysis demonstrate that the three enzymes are endo-splitting enzymes able to break down xylan at random giving xylobio...
Abstract: The production of xylanase and endoglucanase in Clostridium stercorarium has been studied in different conditions. Activities were higher when the organism was grown on xylan and cellulose than on soluble substrates. Catabolite repression of xylanase synthesis occurred when glucose and other readily metabolizable substrates were added during growth on cellulose. Three endoxylanases, A, B, and C, from culture filtrate were purified to homogeneity. Most of the properties of xylanases A, B, and C were similar (optimum pH in the range of 5.5–7.0 at 65 °C; isoelectric pH, 4.4–4.5; Km values of 2.9–3.7 mg/mL). The enzymes were inactivated by Hg2+ and p-chloromercuribenzoate but slight inhibition was obtained with more specific thiol reagents such as 5,5′-dithiobis(2-nitrobenzoic acid) and N-ethylmaleimide. Carbohydrate content (3–19%) and half-life (2 min 30 s to 90 min) varied. Patterns of hydrolysis demonstrate that the three enzymes are endo-splitting enzymes able to break down xylan at random giving xylobio...
88 citations
TL;DR: Twenty-seven thermophilic and thermotolerant fungal strains were isolated from soil, decaying organic matter and sugarcane piles based on their ability to grow at 45°C on medium containing corn straw and cardboard as carbon sources to study xylanase and cellulases under solid state fermentation (SSF).
88 citations
TL;DR: A gene coding for xylanase synthesis in Bacillus subtilis was isolated by direct shotgun cloning using Escherichia coli as a host and shown to be present in a 3.9-kb insert within the PstI site of the plasmid pBR325.
88 citations
TL;DR: It was shown that production of this xylanase was clearly increased when it was produced as a fusion protein with a carrier polypeptide having an intact domain structure compared to the production of fusions to the signal sequence alone or to carriers having incomplete domain structures.
Abstract: A bacterial xylanase gene, Nonomuraea flexuosa xyn11A, was expressed in the filamentous fungus Trichoderma reesei from the strong cellobiohydrolase 1 promoter as fusions to a variety of carrier polypeptides By using single-copy isogenic transformants, it was shown that production of this xylanase was clearly increased (up to 820 mg/liter) when it was produced as a fusion protein with a carrier polypeptide having an intact domain structure compared to the production (150 to 300 mg/liter) of fusions to the signal sequence alone or to carriers having incomplete domain structures The carriers tested were the T reesei mannanase I (Man5A, or MANI) core-hinge and a fragment thereof and the cellulose binding domain of T reesei cellobiohydrolase II (Cel6A, or CBHII) with and without the hinge region(s) and a fragment thereof The flexible hinge region was shown to have a positive effect on both the production of Xyn11A and the efficiency of cleavage of the fusion polypeptide The recombinant Xyn11A produced had properties similar to those of the native xylanase It constituted 6 to 10% of the total proteins secreted by the transformants About three times more of the Man5A core-hinge carrier polypeptide than of the recombinant Xyn11A was observed Even in the best Xyn11A producers, the levels of the fusion mRNAs were only approximately 10% of the level of cel7A (cbh1) mRNA in the untransformed host strain
88 citations
TL;DR: There is no common, coordinated regulatory mechanism that controls the synthesis of mannanase, xylanase, and endoglucanase in the plant-pathogenic basidiomycete Sclerotium rolfsii.
Abstract: Induction of mannanase, xylanase, and cellulase (endoglucanase) synthesis in the plant-pathogenic basidiomycete Sclerotium rolfsii was studied by incubating noninduced, resting mycelia with a number of mono-, oligo-, and polysaccharides. The simultaneous formation of these three endoglycanases could be provoked by several polysaccharides structurally resembling the carbohydrate constituents of lignocellulose (e.g., mannan and cellulose), by various disaccharide catabolites of these lignocellulose constituents (e.g., cellobiose, mannobiose, and xylobiose), or by structurally related disaccharides (e.g., lactose, sophorose, and galactosyl-β-1,4-mannose), as well as by l-sorbose. Synthesis of mannanase, xylanase, and endoglucanase always occurred concomitantly and could not be separated by selecting an appropriate inducer. Various structurally different inducing carbohydrates promoted the excretion of the same multiple isoforms of endoglycanases, as judged from the similar banding patterns obtained in zymogram analyses of enzyme preparations obtained in response to these different inducers and resolved by analytical isoelectric focusing. Whereas enhanced xylanase and endoglucanase formation is strictly dependent on the presence of suitable inducers, increased levels of mannanase are excreted by S. rolfsii even under noninducing, derepressed conditions, as shown in growth experiments with glucose as the substrate. Significant mannanase formation commenced only when glucose was exhausted from the medium. Under these conditions, only very low, presumably constitutive levels of xylanase and endoglucanase were formed. Although the induction of the three endoglycanases is very closely related in S. rolfsii, it was concluded that there is no common, coordinated regulatory mechanism that controls the synthesis of mannanase, xylanase, and endoglucanase.
88 citations