Partial Purification and Characterization of a Thermostable Actinomycete β-Amylase

A thermostable amylase, possibly a β-amylase from Thermoactinomyces sp. no. 2 isolated from soil, is reported. The enzyme was purified 36-fold by acetone precipitation, ion-exchange chromatography, and Sephadex G-200 gel filtration, and the molecular weight was estimated at 31,600. The enzyme was characterized by demonstration of optimum activity at 60°C and pH 7 and by retention of 70% activity at 70°C (30 min). It was stimulated by Mn²⁺ and Fe²⁺ but strongly inhibited by Hg²⁺. Maltose was the only detectable product of hydrolysis of starches and was quantitatively highest in plantain starch hydrolysate.     

Isolation and partial characterisation of extracellular keratinase from a wool degrading thermophilic actinomycete strain Thermoactinomyces candidus.

The keratinase production by the thermophilic actinomycete strain Thermoactinomyces candidus was induced by sheep wool as the sole source of carbon and nitrogen in the cultivation medium. For complete digestion of wool by the above strain, both keratinolytic serine proteinase and cellular reduction of disulfide bonds were involved. Evidence was presented that substrate induction was a major regulatory mechanism and the keratinase biosynthesis was not completely repressed by addition of other carbon (glucose) and nitrogen (NH4C1) sources. The enzyme was purified 62-fold by diethylaminoethyl-anion exchange and Sephadex G-75 gel permeation chromatographies. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the purified keratinase is a monomeric enzyme with a molecular mass of 30 kDa. The pH and temperature optima were determined to be 8.6 and 70 degrees C, respectively. The purified thermophilic keratinase catalyses the hydrolysis of a broad range of substrates and displays higher proteolytic activity against native keratins than other proteinases. Ca2+ was found to have a stabilizing effect on the enzyme activity at elevated temperatures.     

Purification and physical properties of sweet-almond α-galactosidase

1. α-Galactosidase from sweet almonds was purified about 2000-fold through eight steps. 2. The enzyme preparation was free from other related enzymes known to occur in sweet almonds, and behaved as a homogeneous protein on filtration through Sephadex G-75. 3. A molecular weight of about 33000 was determined from the gel-filtration data. 4. The ultraviolet-absorption spectrum and thermal inactivation of the enzyme are described. 5. The purified enzyme hydrolysed p-nitrophenyl α-d-galactoside at a much faster rate than melibiose. 6. The pH optimum was at 5·5–5·7. 7. Besides hydrolysis, it also catalysed transfer of galactosyl residues, chain elongation of melibiose and the synthesis of oligosaccharides from galactose.     

Isolation, Purification, and Some Properties of Penicillium chrysogenum Tannase

Tannase isolated from Penicillium chrysogenum was purified 24-fold with 18.5% recovery after ammonium sulfate precipitation, DEAE-cellulose column chromatography, and Sephadex G-200 gel filtration. Optimum enzyme activity was recorded at pH 5.0 to 6.0 and at 30 to 40°C. The enzyme was stable up to 30°C and within the pH range of 4.0 to 6.5. The K_m value was found to be 0.48 × 10⁻⁴ M when tannic acid was used as the substrate. Metal salts at 20 mM inhibited the enzyme to different levels.     

Halophilic Nuclease of a Moderately Halophilic Bacillus sp.: Production, Purification, and Characterization

A moderately halophilic bacterium, Bacillus sp., isolated from rotting wood on the seashore in Nauru, produced an extracellular nuclease when cultivated aerobically in media containing 1 to 2 M NaCl. The enzyme was purified from the culture filtrate to an electrophoretically homogeneous state by ethanol precipitation, DEAE-Sephadex A-50 column chromatography, and Sephadex G-200 gel filtration. The enzyme consisted of two charge isomers and showed both RNase and DNase activities. Molecular weight was estimated to be 138,000 by Sephadex G-200 gel filtration. The enzyme had marked halophilic properties, showing maximal activities in the presence of 1.4 to 3.2 M NaCl or 2.3 to 3.2 M KCl. The enzyme hydrolyzed thymidine-5′-monophosphate-p-nitrophenyl ester at a rate that increased with NaCl concentration up to 4.8 M. In the presence of both Mg²⁺ and Ca²⁺, activity was greatly enhanced. The activity was lost by dialysis against water and low-salt buffer, but it was protected when 10 mM Ca²⁺ was added to the dialysis buffer. When the inactivated enzyme was dialyzed against 3.5 M NaCl buffer as much as 68% of the initial activity could be restored. The enzyme exhibited maximal activity at pH 8.5 and at 50°C on DNA and at 60°C on RNA and attacked RNA and DNA exonucleolytically and successively, producing 5′-mononucleotides.     

Purification and Partial Characterization of Potato (Solanum tuberosum) Invertase and Its Endogenous Proteinaceous Inhibitor

Invertase plays an important role in the hydrolysis of sucrose in higher plants, especially in the storage organs. In potato (Solanum tuberosum) tubers, and in some other plant tissues, the enzyme seems to be controlled by interaction with an endogenous proteinaceous inhibitor. An acid invertase from potato tubers (variety russet) was purified 1560-fold to electrophoretic homogeneity by consecutive use of concanvalin A-Sepharose 4B affinity chromatography, DEAE-Sephadex A-50-120 chromatography, Sephadex G-150 chromatography, and DEAE-Sephadex A-50-120 chromatography. The enzyme contained 10.9% carbohydrate, had an apparent molecular weight of 60,000 by gel filtration, and was composed of two identical molecular weight subunits (M_r 30,000). The enzyme had a K_m for sucrose of 16 millimolar at pH 4.70 and was most stable and had maximum activity around pH 5. The endogenous inhibitor was purified 610-fold to homogeneity by consecutive treatment at pH 1 to 1.5 at 37°C for 1 hour, (NH₄)₂SO₄ fractionation, Sephadex G-100 chromatography, DEAE-Sephadex G-50-120 chromatography, and hydroxylapatite chromatography. The inhibitor appears to be a single polypeptide (M_r 17,000) without glyco groups. The purified inhibitor was stable over the pH range of 2 to 7 when incubated at 37°C for 1 hour.     

Purification of keratinase from poultry farm isolate-Scopulariopsis brevicaulis and statistical optimization of enzyme activity

The fungus Scopulariopsis brevicaulis was isolated from poultry farm soil at Namakkal, India. The extracellular keratinase from this fungus was purified to homogeneity by ammonium sulphate precipitation and procedure involving DEAE-Cellulose and Sephadex G-100 chromatographic techniques. The purified enzyme was formed from a monomeric protein with molecular masses of 39 and 36 kDa by SDS–PAGE and gel filtration, respectively. The optimum pH at 40 °C was 8.0 and the optimum temperature at pH 8.0 was 40 °C. The activity of purified keratinase with respect to pH, temperature and salt concentration was optimized by Box–Behnken design experiment. It was shown that a second-order polynominal regression model could properly interpret the experimental data with an R²-value of 0.9957 and an F-value of 178.32, based on the maximum enzyme activity examined. Calculated optimum conditions were predicted to confer a 100% yield of keratinase activity with 5 mM CaCl₂, pH 8.0 and at a temperature of 40 °C. The enzyme was strongly inhibited by PMSF, which suggests a serine residue at or near an active site. The purified keratinase was examined with its potential for dehairing the skin.     

Characterization of a novel <Emphasis Type="Italic">Stenotrophomonas</Emphasis> isolate with high keratinase activity and purification of the enzyme

A feather-degrading bacterium was isolated from poultry decomposition feathers in China. The strain, named L1, showed significant feather-degrading activity because it grew and reproduced quickly on basal medium containing 10 g/L of native feather as the source of energy, carbon, and nitrogen. According to the phenotypic characteristics and 16S rRNA profile, the isolate belongs to Stenotrophomonas maltophilia. Keratinase activity of the isolate was determined during cultivation on raw feathers at different temperatures and initial pH. Maximum growth and feather-degrading activity of the bacterium were observed at 40°C and initial pH ranging from 7.5 to 8.0. The crude enzyme was purified by ammonium sulphate precipitation, Sephadex G-100 chromatographic and ceramic hydroxyapatite (CHT) chromatographic. Its molecular mass estimated as 35.2 kDa in SDS-PAGE. The enzyme had an optimum activity at the pH was 7.8 and the temperature was 40°C. The keratinase was wholly inhibited by a serine protease inhibitor, PMSF. Its activity was activated or inhibited by different metal ions. The keratinase activity of enzyme from strain L1 functioned on different keratins, such as feather, hair, wool, horn, and so on.     

Biosynthesis of Tetrapyrrole Pigment Precursors : Pyridoxal Requirement of the Aminotransferase Step in the Formation of delta-Aminolevulinate from Glutamate in Extracts of Chlorella vulgaris

The aminotransferase that catalyzes the formation of δ-aminolevulinic acid from glutamate-1-semialdehyde or from glutamate in a reconstituted enzyme system was isolated and partially purified from Chlorella vulgaris. The apparent molecular weight of the aminotransferase was determined by Sephadex G-100 and Ultrogel AcA 54 gel filtration to be 60,000 ± 5,000. Catalytic activity of the aminotransferase required pyrixodal phosphate (PALP). The cofactor could not be removed by gel filtration after exposure of the enzyme to PALP. Aminotransferase was inhibited by gabaculine (3-amino-2,3-dihydrobenzoic acid). The concentration of gabaculine required for half maximal inhibition was about 0.05 micromolar. Aminotransferase activity could be regained upon the removal of gabaculine by gel filtration and supplementing the assay medium with PALP. Neither the inhibitory action of gabaculine nor its reversibility was affected by preincubation of the enzyme with the keto acids levulinate and δ-aminolevulinic acid.     

Purification and characterization of a trypsin-like proteinase from the midgut of the larva of the hornet, Vespa orientalis

A proteinase from the larval midgut of Vespa orientalis was purified by exchange chromatography on DEAE-Sephadex A-50 and gel filtration on Sephadex G-75. This purified enzyme was proved to be homogeneous by electrophoresis on a cellulose acetate membrane. The molecular weight was calculated to be 27,000 by gel filtration. Optimum pH for the hydrolysis of N-benzoyl-arginine-ethyl ester (BAEE) was 7·5 to 8·5, and optimum temperature with casein as a substrate was 60°C at pH 8·0 for 20 min. According to studies with synthetic inhibitors the hornet protease belongs to the ‘serine proteases’, being inhibited by phenylmethyl sulphonylfluoride (PMSF) and tosyl-lysyl chloromethane (TLCK). The hydrolysis of different amino acid ester bonds and the cleavage specificity on the B chain of oxidized insulin allow us to speak of a trypsin-like protease.     

Isolation, Identification, and Characterization of a Feather-Degrading Bacterium

A feather-degrading culture was enriched with isolates from a poultry waste digestor and adapted to grow with feathers as its primary source of carbon, sulfur, and energy. Subsequently, a feather-hydrolytic, endospore-forming, motile, rod-shaped bacterium was isolated from the feather-degrading culture. The organism was Gram stain variable and catalase positive and demonstrated facultative growth at thermophilic temperatures. The optimum rate of growth in nutrient broth occurred at 45 to 50°C and at pH 7.5. Electron microscopy of the isolate showed internal crystals. The microorganism was identified as Bacillus licheniformis PWD-1. Growth on hammer-milled-feather medium of various substrate concentrations was determined by plate colony count. Maximum growth (approximately 10⁹ cells per ml) at 50°C occurred 5 days postinoculation on 1% feather substrate. Feather hydrolysis was evidenced as free amino acids produced in the medium. The most efficient conditions for feather fermentation occurred during the incubation of 1 part feathers to 2 parts B. licheniformis PWD-1 culture (10⁷ cells per ml) for 6 days at 50°C. These data indicate a potential biotechnique for degradation and utilization of feather keratin.     

Bacteriolytic enzymes from Staphylococcus aureus. Purification of an endo-β-N-acetylglucosaminidase

On cultivation of Staphylococcus aureus in a complex liquid medium, bacteriolytic activity is found extracellularly. The maximal amount was found at the end of the exponential growth phase in batch culture, but in continuous culture run under similar conditions the yield was doubled. Isoelectric focusing of dialysed crude culture supernatants showed that the bacteriolytic activity of all four strains studied (M18, 524, Wood 46 and Duncan) was heterogeneous. The most alkaline peak of activity (isoelectric point 9.5±0.1) was assayed against Micrococcus lysodeikticus turbidimetrically. This bacteriolytic activity was purified more than 70-fold after continuous dialysis by adsorption on CM-Sephadex, precipitation with ethanol, heat purification, isoelectric focusing and Sephadex G-100 chromatography. The purified enzyme (isoelectric point 9.6±0.1) was found to give a single band on polyacrylamide-gel and cellulose acetate electrophoresis and was devoid of all 14 staphylococcal enzymes and toxins assayed for. The molecular weight is 70000±5000 as estimated by Sephadex G-100 and G-200 chromatography. The marked instability of the partially and highly purified enzyme was investigated. The mode of action and some properties of this enzyme are given in the following papers (Wadström & Hisatsune, 1970; Wadström, 1970). These results indicate that this extracellular enzyme which is produced by several strains of S. aureus is not a `lysozyme' (endo-β-N-acetylmuramidase) as previously suggested, but an endo-β-N-acetylglucosaminidase.     

Optimized Expression of a Thermostable Xylanase from Thermomyces lanuginosus in Pichia pastoris

Highly efficient production of a Thermomyces lanuginosus IOC-4145 β-1,4-xylanase was achieved in Pichia pastoris under the control of the AOX1 promoter. P. pastoris colonies expressing recombinant xylanase were selected by enzymatic activity plate assay, and their ability to secrete high levels of the enzyme was evaluated in small-scale cultures. Furthermore, an optimization of enzyme production was carried out with a 2³ factorial design. The influence of initial cell density, methanol, and yeast nitrogen base concentration was evaluated, and initial cell density was found to be the most important parameter. A time course profile of recombinant xylanase production in 1-liter flasks with the optimized conditions was performed and 148 mg of xylanase per liter was achieved. Native and recombinant xylanases were purified by gel filtration and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, circular dichroism spectroscopy, matrix-assisted laser desorption ionization-time of flight-mass spectrometry and physicochemical behavior. Three recombinant protein species of 21.9, 22.1, and 22.3 kDa were detected in the mass spectrum due to variability in the amino terminus. The optimum temperature, thermostability, and circular dichroic spectra of the recombinant and native xylanases were identical. For both enzymes, the optimum temperature was 75°C, and they retained 60% of their original activity after 80 min at 70°C or 40 min at 80°C. The high level of fully active recombinant xylanase obtained in P. pastoris makes this expression system attractive for fermentor growth and industrial applications.     

Codon Optimization Significantly Improves the Expression Level of a Keratinase Gene in Pichia pastoris

The main keratinase (kerA) gene from the Bacillus licheniformis S90 was optimized by two codon optimization strategies and expressed in Pichia pastoris in order to improve the enzyme production compared to the preparations with the native kerA gene. The results showed that the corresponding mutations (synonymous codons) according to the codon bias in Pichia pastoris were successfully introduced into keratinase gene. The highest keratinase activity produced by P. pastoris pPICZαA-kerAwt, pPICZαA-kerAopti1 and pPICZαA-kerAopti2 was 195 U/ml, 324 U/ml and 293 U/ml respectively. In addition, there was no significant difference in biomass concentration, target gene copy numbers and relative mRNA expression levels of every positive strain. The molecular weight of keratinase secreted by recombinant P. pastori was approx. 39 kDa. It was optimally active at pH 7.5 and 50°C. The recombinant keratinase could efficiently degrade both α-keratin (keratin azure) and β-keratin (chicken feather meal). These properties make the P. pastoris pPICZαA-kerAopti1 a suitable candidate for industrial production of keratinases.     

Purification and Characterization of an Extremely Thermostable Cyclomaltodextrin Glucanotransferase from a Newly Isolated Hyperthermophilic Archaeon, a Thermococcus sp.

The extremely thermophilic anaerobic archaeon strain B1001 was isolated from a hot-spring environment in Japan. The cells were irregular cocci, 0.5 to 1.0 μm in diameter. The new isolate grew at temperatures between 60 and 95°C (optimum, 85°C), from pH 5.0 to 9.0 (optimum, pH 7.0), and from 1.0 to 6.0% NaCl (optimum, 2.0%). The G+C content of the genomic DNA was 43.0 mol%. The 16S rRNA gene sequencing of strain B1001 indicated that it belongs to the genus Thermococcus. During growth on starch, the strain produced a thermostable cyclomaltodextrin glucanotransferase (CGTase). The enzyme was purified 1,750-fold, and the molecular mass was determined to be 83 kDa by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Incubation at 120°C with SDS and 2-mercaptoethanol was required for complete unfolding. The optimum temperatures for starch-degrading activity and cyclodextrin synthesis activity were 110 and 90 to 100°C, respectively. The optimum pH for enzyme activity was pH 5.0 to 5.5. At pH 5.0, the half-life of the enzyme was 40 min at 110°C. The enzyme formed mainly α-cyclodextrin with small amounts of β- and γ-cyclodextrins from starch. This is the first report on the presence of the extremely thermostable CGTase from hyperthermophilic archaea.     

Isolation and Some Properties of Glucoamylase from Cephalosporium charticola Lindau

High glucoamylase (α-D-/1 → 4/glucan glucohydrolase, EC 3.2.1.3.) activity was obtained in the cell-free culture fluid of Cephalosporium charticola. Glucoamylase seems to be the only amylolytic enzyme produced by C. charticola. The enzyme, purified on diethylaminoethyl-cellulose, was homogeneous by disc gel electrophoresis. The optimum pH on starch was 5.4, and optimum temperature was 60 C. Starch was degraded more rapidly than several other substrates; maltose was hydrolyzed about one-fifth as rapidly as starch. The molecular weight was 69,000, as determined by Sephadex G-100 filtration. The enzyme is a glycoprotein and contains about 6.6% sugars (mannose and glucosamine).     

Purification, crystallization and properties of triacylglycerol lipase from Pseudomonas fluorescens.

Triacylglycerol lipase of Pseudomonas fluorescens was purified from the crude enzyme by ammonium sulfate precipitation and chromatographies on Sephadex G-75 and DEAE-cellulose. The crystallization of the lipase was successfully carried out. The purified lipase was demonstrated to be homogenous on disc electrophoresis and its molecular weight was calculated to be 32 000 by gel filtration. The optimum pH for hydrolysis of sesame oil was 7.0. The enzyme was stable up to 40 degrees C under the condition of pH 7.0 for 30 min and had more than 80% of the remaining activity between pH 5.0--11.0 at 37 degrees C for 60 min. The lipase was strongly inhibited by iodine and partially inhibited by FeCl3 and N-bromosuccinimide, and showed the most activity on tricaproyglycerol, among the triacylglycerols used.     

Purification and properties of a keratinolytic metalloprotease from Microbacterium sp

AIMS: This study was developed to purify and to characterize a keratinolytic protease from the bacterium Microbacterium sp. strain kr10. METHODS AND RESULTS: Enzyme purification was carried out by sequential liquid chromatography on Sephadex G-100 and Q-Sepharose columns. The purification was about 255-fold, with a yield of 34%, as determined with azocasein as substrate. The molecular weight of the enzyme was estimated as 42,000 Da by SDS-PAGE. The enzyme had pH and temperature optima of 7.5 and 50 degrees C respectively. This keratinase was inhibited by EDTA and 1,10-phenanthroline, and analysis of metal content indicates that Zn(2+) and Mg(2+) are present. A 2(2) factorial design was developed to investigate the effect of keratinase and mercaptoacetate concentration on feather keratinolysis. Statistical analysis showed that both variables have a significant effect on hydrolysis of keratin. CONCLUSIONS: A new keratinase produced by Microbacterium sp. was purified and characterized. SIGNIFICANCE AND IMPACT OF THE STUDY: This keratinolytic enzyme offers an interesting potential for the hydrolysis of keratin wastes to be used as feed supplement or bioconversion to added-value products.     

Properties of a Clostridium thermocellum Endoglucanase Produced in Escherichia coli

A cellulase gene of Clostridium thermocellum was transferred to Escherichia coli by molecular cloning with bacteriophage lambda and plasmid vectors and shown to be indentical with the celA gene. The celA gene product was purified from extracts of plasmid-bearing E. coli cells by heat treatment and chromatography on DEAE-Trisacryl. It was characterized as a thermophilic endo-β-1,4-glucanase, the properties of which closely resemble those of endoglucanase A previously isolated from C. thermocellum supernatants. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis the enzyme purified from E. coli exhibited two protein bands with molecular weights of 49,000 and 52,000. It had a temperature optimum at 75°C and was stable for several hours at 60°C. Endoglucanase activity was optimal between pH 5.5 and 6.5. The enzyme was insensitive against end product inhibition by glucose and cellobiose and remarkably resistant to the denaturing effects of detergents and organic solvents. It was capable of degrading, in addition to cellulosic substrates, glucans with alternating β-1,4 and β-1,3 linkages such as barley β-glucan and lichenan.     

Characterization of an endo-Acting Amylopullulanase from Thermoanaerobacter Strain B6A

A thermoanaerobe (Thermoanaerobacter sp.) grown in TYE-starch (0.5%) medium at 60°C produced both extra- and intracellular pullulanase (1.90 U/ml) and amylase (1.19 U/ml) activities. Both activities were produced at high levels on a variety of carbon sources. The temperature and pH optima for both pullulanase and amylase activities were 75°C and pH 5.0, respectively. Both the enzyme activities were stable up to 70°C (without substrate) and at pH 4.5 to 5.0. The half-lives of both enzyme activities were 5 h at 70°C and 45 min at 75°C. The enzyme activities did not show any metal ion activity, and both activities were inhibited by β- and γ-cyclodextrins but not by α-cyclodextrin. A single amylolytic pullulanase responsible for both activities was purified to homogeneity by DEAE-Sepharose CL-6B column chromatography, gel filtration using high-pressure liquid chromatography, and pullulan-Sepharose affinity chromatography. It was a 450,000-molecular-weight glycoprotein composed of two equivalent subunits. The pullulanase cleaved pullulan in α1,6 linkages and produced multiple saccharides from cleavage of α-1,4 linkages in starch. The K_ms for pullulan and soluble starch were 0.43 and 0.37 mg/ml, respectively.