1,720,986 research outputs found
Purification and properties of an endopolygalacturonase produced by Rhizopus stolonifer
No full textA polygalacturonase from culture filtrates of a strain of Rhizopus stolonifer was purified about 80 fold by ethanol precipitation, followed by ion exchange chromatography (CM-Sepharose 6B) and gel filtration (Sephadex G-100). The purified preparation was homogeneous when examined by PAGE. The enzyme is an endopolygalacturonase with an optimum catalytic activity at pH 5.0 and 45°C, and a molecular weight of 57,000±500 daltons. The activity was stimulated by Fe+++, Mg++, Co++, and inhibited by Mn++ and Zn++. The enzyme was stable in the pH range of 3.0 to 5.0. The purified enzyme was specific for nonmethoxylate polygalacturonic acid, with Km and Vmax values respectively of 0.19 mg/ml and 1.3 mol/ g/min. In addition, this enzymatic preparation degraded pectic substances in orange peel
Phenotypic and genotypic characterization of a sporeforming strain producing proteolytic activity
No full textThermostable alkaline protease produced by Bacillus thermoruber, a new species of Bacillus
No full text• The proteolytic activity produced by a new species of Bacillus isolated in our laboratory was investigated. This enzyme was purified to homogeneity from cell-free culture liquids of B. thermoruber. The purification procedure included ion-exchange chromatography on DEAE-Sephadex A-50 and -casein agarose affinity chromatography. The protease consists of one polypeptide chain with a molecular weight of 39000±800. the isoelectric point was 5.3; the optimum pH and temperature for proteolytic activity (on casein) was found to be pH 9 and 45°C respectively. Enzyme activity was inhibited by PMSF and EDTA. The stability was considerably increased by addition of Ca2+, and the protease exhibited a relatively high thermal stability. The alkaline protease shows a preference for leucine in the carboxylic side of the peptide bond of the substrate. The K m value for benzyloxycarbonyl-Ala-Ala-Leu-p-nitroanilide was 2.5 mM
Enzymic modification of vegetable protein by a crude preparation from a strain of Bacillus licheniformis
No full textSunflower seed proteins are of interest for their functionality, and for their nutritional quality which arises from a balanced amino acid pattern and the absence of antinutritional factors (Jaya et a1 1981; Rossi et a1 1985). Furthermore, sunflower meal is readily available after the oil extraction process. This communication reports the results of a preliminary study carried out to evaluate the ability of a crude proteolytic enzyme preparation, obtained from a strain of Bacillus licheniformis isolated in this laboratory, to hydrolyse proteins of different source. In particular, sunflower protein concentrate was investigated. Factors affecting the extent of enzymic hydrolysis, such as substrate concentration, pH, temperature, and some characteristics of the hydrolysates obtained, were studied
Pectic enzymes from Aureobasidium pullulans LV10
No full text• Aureobasidium pullulans LV 10 produced extracellular pectolytic activity when grown in a medium containing apple pectin as a carbon source. Maximum enzyme production (22 PGU ml−1 and 9 PLU ml−1) was obtained after 4 days of batch growth. Two pectin hydrolases and two pectin lyases by CM-Sepharose 6B, DEAE-cellulose, and Sephadex G-100 column chromatography were partially purified and characterized. Hydrolases I and II gave optimum activity at pH 5.5 and 4.5, respectively, at 50°C. For lyases I and II, the optimum occurred at pH 5.0 and 7.5, respectively, and 40°C
BliI, a restriction endonuclease from Bacillus licheniformis
No full textAbstractFrom Bacillus licheniformis a site-specific restriction endonuclease, named BliI, has been purified and characterized. BliI was able to digest λ DNA at pH 9.1 over a wide temperature range (25–65°C). Digestion of λ and (ϕX174 DNAs with BliI produced banding patterns identical to those seen with HaeIII. Therefore, BliI and HaeIII endonculeases are isoschizomers
Genetic relationship among Bacillus licheniformis rolling-circle-replicating plasmids and complete nucleotide sequence of pBL63.1, an atypical replicon
No full textThe degree of biodiversity among Bacillus licheniformis plasmids and their relation to other Bacillus subtilis group plasmids has been evaluated. To attain this goal we surveyed the diversity and linkage of replication modules in a collection of 21 naturally occurring plasmids of B. licheniformis strains, isolated from different geographical areas. On the basis of rep gene sequence analysis it was possible to group the B. licheniformis plasmids rep genes in two main cluster. Comparison with known rep genes from Bacillus rolling-circle-replicating (RCR) plasmids revealed the presence in B. licheniformis plasmids of replication genes with a DNA sequence peculiar to B. licheniformis species together with rep genes with a very high sequence similarity to B. subtilis plasmids. Furthermore, the molecular organization of an atypical replicon, pBL63.1, was shown. This plasmid did not display any significant similarity with known Bacillus RCR plasmids. The complete nucleotide sequence evidenced a replication module with an unexpected similarity with Rep proteins from RCR plasmids of bacterial species phylogenetically distantly related to Bacillus. pBL63.1 represents an exception to the low-level diversity hypothesis among Bacillus RC replicons
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