β-D-Xylanases of Bacillus circulans WL-12

Abstract

Bacillus circulans WL-12 secretes two endo-β-D-xylanases (A and B, respectively) (EC 3.2.1.8.) and one β-D-xylosidase (EC 3.2.1.37) when cultured in liquid media with xylan as the sole carbon source. Xylanases A and B have been partially characterized with respect to their main physicochemical parameters and β-D-xylosidase to a lesser extent on account of its low stability. Both endo-β-D-xylanase A and β-D-xylosidase were adsorbed on DEAE-Biogel A, had similar molecular weights (approximately 85 000), and had optimum pH values of 5.5–7, but exhibited different isoelectric points (4.5 for β-D-xylanase A and 4.7 for β-D-xylosidase) and different mobilities in polyacrylamide gel electrophoresis. The apparent Michaelis constant for β-D-xylanase A was 8 mg∙mL−1 and the hydrolysis products produced were xylose, xylobiose, xylotriose, and xylotetraose.The second endo-β-D-xylanase (β-D-xylanase B) bound to CM-Biogel A and exhibited a molecular weight of approximately 15 000 and an optimum pH value in the range of 5.5–7. The isoelectric point was 9.1 and the apparent Michaelis constant was 4 mg∙mL−1. The hydrolysis products produced by this enzyme were xylobiose, xylotriose, and xylotetraose, but never xylose. In polyacrylamide gel electrophoresis at pH 8 the enzyme moved towards the negative electrode.

Recombinant Xylanase from Bacillus tequilensis BT21: Biochemical Characterization and Its Application in Production of Xylobiose from Agricultural Residues

“…(NCL 87-6--10) produces two xylanases, A, with the molecular mass of 44 kDa and pI=5.3, and C, with 25 kDa and pI=8.9 (35). Similarly, there are reports that B. circulans and B. polymyxa produce high-and low-molecular mass xylanases with acidic and basic pI respectively (20,35). Proteins with acidic isoelectric points degraded faster than those with neutral or basic isoelectric points (36), which might be because of chemical properties of the acidic or basic polypeptides.…”

Production of lignocellulolytic enzymes by Trametes gallica and detection of polysaccharide hydrolase and laccase activities in polyacrylamide gels

“…Microorganisms capable of hydrolyzing cellulose and hemicellulose are widely distributed amongst various taxa: fugi (FREDERICK et al 1981, GORBACHEVA and RODIONOVA 1977, HALTRICH et al 1996, actinomycetes and bacteria (BERNIER et al 1983, ESTEBAN et al 1982. Cellulose and hemicellulose are enzymatically hydrolyzed by a group of enzymes, respectively, such as endo-β-glucanases, endo-β-xylanases and so on.…”

Enzymic Dissociation of Zea Shoot Cell Wall Polysaccharides

“…The summary data for purification are presented in Table I. Gel filtration pattern of xylanase-I-I-i on a Bio-Gel P-10 column.. A 3.5-mg sample of protein was applied to a Bio-Gel P-lO column (1.5 x 140 cm) preequilibrated with 10 mM Na-phosphate buffer, pH 6.0 followed by filtration through the column with the same buffer.…”