Arg²³⁵ is an essential catalytic residue of Bacillus pumilus DKS1 pectate lyase to degum ramie fibre.
ABSTRACT After 24 h of incubation with only purified pectate lyase isolated from Bacillus pumilus DKS1 (EF467045), the weight loss of the ramie fibre was found to be 25%. To know the catalytic residue of pectate lyase the pel gene encoding a pectate lyase from the strain Bacillus pumilus DKS1 was cloned in E. coli XL1Blue and expressed in E. coli BL21 (DE3) pLysS. The pel gene was sequenced and showed 1032 bp length. After purification using CM-Sepharose the enzyme showed molecular weight of 35 kDa and maximal enzymatic activity was observed at 60°C and a pH range of 8.5-9.0. Both Ca²(+) and Mn²(+) ions were required for activity on Na-pectate salt substrates, while the enzyme was strongly inhibited by Zn²(+) and EDTA. The deduced nucleotide sequence of the DKS1 pectate lyase (EU652988) showed 90% homology to pectate lyases from Bacillus pumilus SAFR-032 (CP000813). The 3D structure as well as the catalytic residues was predicted using EasyPred software and Catalytic Site Atlas (CSA), respectively. Site directed mutagenesis confirmed that arginine is an essential catalytic residue of DKS1 pectate lyase.
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ABSTRACT: This review addresses the potential biotechnological techniques for textile fibre extraction (degumming), mainly focusing on bamboo, one of the main and recently developed textile natural fibres in China. The latest developments in microbial and enzymatic processing for ecological fibre extraction as well as the development of a molecular technique for natural fibre bio-treatment are highlighted.Biocatalysis and Biotransformation 01/2012; 30(1). · 0.90 Impact Factor
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ABSTRACT: A newly isolated bacterial strain, Bacillus sp. MX47, was actively producing extracellular xylanase only in xylan-containing medium. The xylanase was purified from the culture broth by two chromatographic steps. The xylanase had an apparent molecular weight of 26.4 kDa with an NH(2)-terminal sequence (Gln-Gly-Gly-Asn-Phe) distinct from that of reported proteins, implying it is a novel enzyme. The optimum pH and temperature for xylanase activity were 8.0 and 40 °C, respectively. The enzyme activity was severely inhibited by many divalent metal ions and EDTA at 5 mM. The xylanase was highly specific to beechwood and oat spelt xylan, however, not active on carboxymethyl cellulose (CMC), avicel, pectin, and starch. Analysis of the xylan hydrolysis products by Bacillus sp. MX47 xylanase indicated that it is an endo-β-1,4-xylanase. It hydrolyzed xylan to xylobiose as the end product. The K (m) and V (max) values toward beechwood xylan were 3.24 mg ml(-1) and 58.21 μmol min(-1) mg(-1) protein, respectively.Applied biochemistry and biotechnology 09/2012; 168(4):899-909. · 1.94 Impact Factor
Conference Paper: Temporal averaging of multitemporal ERS-1/2 Tandem INSAR data[Show abstract] [Hide abstract]
ABSTRACT: In this study the potential of multitemporal ERS-1/2 SAR Tandem interferometry in land-use classification was investigated. Emphasis was on classifying land-use near urban centres, where the land-use features are typically small and high resolution is therefore desired. A high-quality orthorectified multitemporal interferometric dataset was created for further study. Temporal averaging, i.e. averaging over several intensity and coherence images reduces noise and increased the amount of discernible features without degrading the image resolution. At this stage of the study only visual classification has been done, temporal averaging was found to increase the number of visually discernible classes in the imageryGeoscience and Remote Sensing Symposium, 2000. Proceedings. IGARSS 2000. IEEE 2000 International; 02/2000