Studies on the Xylanase from Streptomyces

Xylanase from Streptomyces xylophagus nov. sp. has been purified by ammonium sulfate fractionation and chromatography on DEAE-cellulose column. The purification of the enzyme was 276-fold with a yield of 18.6% on the basis of the activity per weight of total nitrogen. The purified enzyme was homogeneous on moving-boundary electrophoresis. Optimum pH and temperature for the enzyme activity were 6.2 and 55~60°C, respectively. The enzyme was stable up to 40°C and in the range of pH from 5.3 to 7.3, but inactivated at higher than 50°C and at extreme pH values of 2.4 and 9.4. Hydrolyzed products of xylan by the enzyme were xylose and xylobiose.     

Studies on an Alkaline Proteinase of Aspergillus sydowi

An alkaline proteinase of Aspergillus sydowi (Bainier et Sartory) Thom et Church has been purified approximately 4.5-fold from a culture filtrate by fractionation with ammonium sulfate, treatment with acrynol and Alumina gel C_γ, and DEAE-Sephadex column chromatography. The purified proteinase obtained as needle crystals was monodisperse in both the ultracentrifuge and the electrophoresis on polyacrylamide gel.

The optimum pH and temperature for the activity were 8.0 and 40°C, respectively. Fifty per cent of the activity was lost at 45°C within ten minutes and 95% at 50°C. At 5°C, the enzyme was highly stable at the range of pH 6 to 9. None of metallic salts tested promoted the activity, but Zn⁺⁺, Ni⁺⁺ and Hg⁺⁺ were found to be inhibitory. Sulfhydryl reagent, reducing and oxidizing reagents tested except iodine had no effect on the activity, but potato inhibitor, DFP and NBS caused a marked inhibition.

The alkaline proteinase from Aspergillus sydowi was markedly protected from inactivation by the presence of Ca⁺⁺ in the enzyme solution. The protective effect of Ca⁺⁺ was influenced remarkably by the pH values of the enzyme solution, i.e., optimum concentrations of Ca⁺⁺ for the protective effect at pH 7.1, 7.5 and 7.8 were 10^?2, 10^?3 and 10^?4 M, respectively. Conversely, at higher pH values such as 9.0, Ca⁺⁺ accelerated the rate of inactivation. There was a parallelism between the loss in activity and the increase in ninhydrin-positive material in the enzyme solution.

The proteinase acted on various denaturated proteins, but not on native proteins. In digestion of casein by the proteinase, 92% of nitrogen was turned into soluble form in 0.2 m trichloroacetic acid solution, with 14~17% of peptide bonds being hydrolyzed. Casein hydrolyzed with the Asp. sydowi proteinase was further hydrolyzed by Pen. chrysogenum, B. subtilis or St. griseus proteinases, which further increased the free amino residues in the reaction mixtures. On the contrary, the Asp. sydowi proteinase reacted only slightly on casein hydrolyzed by the above-mentioned proteinases.     

An Isomaltotriose-producing Dextranase from Flavobacterium sp. M-73: Purification and Properties

An isomaltotriose-producing dextranase II, detected in the culture supernatant of Flavobacterium sp. M-73, was purified to an electrophoretically pure state. Successive chromatography on hydrophobic columns of Amberlite CG-50 and aminooctyl-Sepharose was very effective as the first step of purification. Further purification of the enzyme was performed by affinity column chromatography on isomaltotriose-Sepharose and preparative polyacrylamide gel electrophoresis.

The purified enzyme was shown to be a monomer and had a molecular weight of 114,000. Dextranase II was most active at pH 7.0 and 35°C. It was stable at 4°C for 24 hr over a pH range of 6.5～12.0 and up to 35°C on heating for 10 min. This enzyme had a strict specificity for consecutive α-l,6-glucosidic linkages and readily hydrolyzed clinical dextran and Sephadex gels. The degree of hydrolysis of clinical dextran was 31% expressed as apparent conversion into D-glucose. The amount of isomaltotriose in the hydrolyzate was determined to be 63%.     

Studies on Tannin Acyl Hydrolase of Microorganisms

Tannin acyl hydrolase (Tannase) from Asp. oryzae No. 7 was purified. The purified enzyme was homogenous on column chromatography (DEAE-Sephadex A50, Sephadex G100), ultra centrifugation and electrophoresis.

The molecular weight of the enzyme estimated by gel filtration method was about 200,000.

The enzyme was stable in the range of pH 3 to 7.5 for 12 hr at 5°C, and for 25 hr at the same temperature in the range of pH 4.5 to 6. The optimum pH for the reaction was 5.5. It was stable under 30°C (over one day, in 0.05 M-citrate buffer of pH 5.5), and the optimum temperature was 30~40°C (reaction for 20min). The activity was lost completely at 55°C in 20 min at pH 5.5, or at 85°C in 10 min at the same pH.

Any metal salt tested did not activate the enzyme, Zink chloride and cupric chloride inhibited the activity or denatured the enzyme. The activity was lost completely by dialysis against EDTA-solution at pH 7.25, although it was not affected by dialysis against deionized water.     

Serratia Protease

A strain of Serratia, isolated from an intestinal canal of a silkworm, produced a large quantity of protease. The enzyme was extracellular and was named Serratiopeptidase, tentatively. Protease production of this strain was over 3 times as much as that of Serratia marcescens which was known as a protease-producing organism. The highly purified enzyme was prepared from the culture supernatant through ammonium sulfate precipitation, acetone fractionation, DEAE-cellulose column chromatography and gel filtration on Sephadex G-75.

The purified enzyme moved homogeneously with a sedimentation constant, s_20,w of 3.8 S in ultracentrifugation and the molecular weight was determined to be 6.0 × 10₄ by the Archibald method. Determination of the ultraviolet absorption spectrum indicated the E^1%_{280 mμ,1 cm} was 13.0. Neither carbohydrate nor sulfur-containing amino acid was detected in the purified enzyme preparation. The enzyme showed maximal activity at pH 9.0 and at 40°C, and was stable under lower temperatures over the pH range from 5 to 10, whereas it was unstable at 37°C in alkaline conditions. The enzyme was completely inactivated by heating at 55°C for 15 min.     

Purification,Crystallization and Some Properties of Extracellular Pullulanase from Aerobacter aerogenes

Extracellular pullulanase was purified and crystallized from the culture fluid of Aerobacter aerogenes. Pullulanase was purified by means of ammonium sulfate fraction, DEAE-cellulose column chromatography and Sephadex column chromatography. Crystalline pullulanase was formed when saturated ammonium sulfate solution was added to the purified enzyme solution. The crystalline enzyme appeared as colorless fine rods. On ultracentrifugation analysis, the enzyme showed a single sharp and symmetrical Schlieren peak. The sedimentation coefficient, s_20,w was 4.39S. Polyacrylamide gel electrophoresis at pH 8.4 gave a main band with two sub-bands and the molecular weight of the main enzyme was estimated to be 66,000 from Polyacrylamide gel electrophoresis and to be 58,000 from sedimentation equilibrium. The optimum pH and temperature for the enzyme action were pH 6.5 and 50°C, respectively.     

Milk Clotting Enzyme from Microorganisms

The purification of the milk clotting enzyme from Mucor pusillus Lindt could be achieved by column chromatography on Amberlite IRC-50 by raising pH from 3.5 to 4.5 and about 70% of activity was recovered after this treatment. After the treatment through the column of DEAE-Sephadex A-25, the trace cellulase activity could be eliminated.

The homogeneity of the purified preparation was proved by ultracentrifugal analysis and electrophoretic patterns at various pH values.

Isoelectric point of this enzyme is considered to lie between pH 3.5 and 3.8.

The enzyme activity was inhibited by Hg⁺⁺ or Fe⁺⁺⁺.

Trypsinogenkinase activity was not contained in this enzyme.

The antiserum against the milk clotting enzyme from Mucor pusillus reacted with the purified and crude enzyme preparations in precipitin test and inhibited their enzyme activities, but did not react with other enzymes such as rennin, pepsin, acid proteases from Aspergillus saitoi and Aspergillus oryzae, or the culture filtrates of some strains of Mucor and Rhizopus.

The antigen-antibody reaction was so specific that it might be possible with this antibody to identify this enzyme and also the strain itself.

Normal sera from some mammals inhibited this enzyme activity too, but the degree was less than that with rennin.     

Purification and physicochemical properties of an extra-cellular cycloamylose (cyclodextrin) glucanotransferase from Bacillus macerans

An extracellular cycloamylose (cyclodextrin) glucanotransferase (EC 2.4.1.19) from Bacillus macerans was purified to homogeneity by adsorption on starch, ammonium sulfate fractionation, column chromatography on DEAE-cellulose, and gel filtration on Sephadex G-100. The enzyme had a molecular weight of 67,000 and consisted of one polypeptide chain. The isoelectric point was pH 5.4. Temperature and pH optima were 60° and 5.45.8, respectively. The purified enzyme was quite stable at 50° (pH 6.0), but lost ≈80% of its activity at 60° for 30 min (pH 6.0). Prolonged digestion by trypsin did not affect the catalytic properties of the enzyme. The K_m for starch was 5.7 mg/ml.     

Purification and Properties of Phospholipase D from Streptomyces antibioticus

Phospholipase D was purified from Streptomyces antibioticus by column chromatography and chromatofocusing. The enzyme preparation was electrophoretically homogeneous and the molecular weight of the enzyme was estimated to be 64,000. Its isoelectric point was around pH 6.5. The enzyme was most active at pH 5.5 and at around 60°C. It was stable between pH 4 and 8, and below 50°C.     

Purification and Some Properties of Cyclomaltodextrin Glucanotransferase from Bacillus circulans

Cyclomaltodextrin glucanotransferase was purified from B. circulans C31 through two successive steps of starch and Biogel column chromatography. The enzyme was purified up to 90-fold with a 30% yield. Its molecular weight was around 103,000. The purified enzyme converted 28% of the soluble starch to β-cyclodextrin at pH 7.0 and a substrate concentration of 5%. The optimum pH for the enzyme was found to be 5.5. The optimum temperature was 60°C. The enzyme optimum was stable from pH 5.5~9.0 and up to 50°C.     

Studies on Pectolytic Enzymes of Molds

Exopolygalacturonase from Coniothyrium diplodiella has been purified by ammonium sulfate fractionation, chromatography on DEAE-cellulose and column zone electrophoresis. The enzyme was concentrated about 5-fold with a yield of 0.24% on the basis of polygalacturonase activity per weight of total nitrogen. The purified enzyme was homogenous On free-boundary electrophoresis. The enzyme was most active in the pH range 4.0~4.5. The enzyme was stable at 50°C and pH range of 3.5~6.0, but inactivated at higher than 55°C. Hydrolysis of pectic acid by the enzyme went to completion via galacturonic acid liberation from the end of the chain, but pectin was little affected by the enzyme.     

Purification and characterization of an extracellular β-xylosidase from a newly isolated Fusarium verticillioides

An extracellular β-xylosidase from a newly isolated Fusarium verticillioides (NRRL 26518) was purified to homogeneity from the culture supernatant by concentration by ultrafiltration using a 10,000 cut-off membrane, ammonium sulfate precipitation, DEAE Bio-Gel A agarose column chromatography and SP-Sephadex C-50 column chromatography. The purified β-xylosidase (specific activity, 57 U/mg protein) had a molecular weight (mol. wt.) of 94,500 and an isoelectric point at pH 7.8. The optimum temperature and pH for action of the enzyme were 65°C and 4.5, respectively. It hydrolyzes xylobiose and higher xylooligosaccharides but is inactive against xylan. The purified β-xylosidase had a K _m value of 0.85 mM (p-nitrophenol-β-D-xyloside, pH 4.5, 50°C) and was competitively inhibited by xylose with a K _i value of 6 mM. It did not require any metal ion for activity and stability. Journal of Industrial Microbiology & Biotechnology (2001) 27, 241–245. Received 20 May 2001/ Accepted in revised form 06 July 2001     

Purification and Partial Characterization of Alkaline Xylanase from Escherichia coli Carrying pCX311

Xylanase produced by E. coli HB 101 carrying plasmid pCX311, which contains the xylanase A gene of alkalophilic Bacillus sp. strain C-125, was purified by ammonium sulfate precipitation, DEAE-cellulose column chromatography and Sephadex G-75 gel filtration. The purified enzyme had a molecular weight of 43,000. The pH and temperature optima for its activity were 6~10 and 70°C, respectively. The enzyme retained full activity after incubation at 50°C for 10 min. These enzymatic properties of the xylanase were almost the same as those of xylanase A. But this enzyme was less stable than xylanase A at low pHs. Furthermore, we could purify a larger amount of alkaline xylanase from E. coli than from alkalophilic Bacillus sp. strain C-125.     

Phytase from Aspergillus terreus

1) Aspergillus terreus No. 9A-1 was cultivated by a shaking method and the optimal cultural conditions for the phytase production were concluded as follows: Composition of medium; rice bran 30 g, ammonium sulfate 3 g, distilled water 1.0 liter; initial pH 5.5; shaking condition; 50 ml of medium/500 ml vol. flask; 120 oscil./min, 90 hr.

2) Phytase from Asp. terreus was purified by ammonium sulfate precipitation, acetone precipitation and chromatography on SE-Sephadex C-50 and Sephadex G-200 columns. The enzyme was purified about 520-folds with the yield of 20% from the broth. The purified enzyme was homogeneous by column chromatography, ultracentrifugation and electrophoresis.

3) This purified preparation of phytase showed following properties, a) Optimal pH for the reaction was 4.5; b) optimal temperature for the reaction was about 70°C; c) the enzyme was stable in the range of pH from 1.2 to 9.0     

Purification and Characterization of an Endopolygalacturonase Produced by Sclerotinia Sclerotiorum

An endopolygalacturonase (endo-PG), was purified from the culture medium of a local isolate of Sclerotinia sclerotiorum with ammonium sulphate precipitation, cation exchange chromatography and gel filtration. The purified endo-PG had a molecular mass of approximately 18 kDa estimated by gel filtration. The isoelectric point was determined by isoelectric focusing to be approximately 8, suggesting that PG II possesses a net positive charge at physiological pHs. The pH optimum for the enzyme was at pH 4.5. The endo-PG showed essentially the same affinity for pectin and polygalacturonic acid as substrates. This revised version was published online in July 2006 with corrections to the Cover Date.     

Purification and Properties of an Asymmetric Reduction Enzyme of 2-Methyl-3-oxobutyrate in Baker’s Yeast

The benzyl 2-methyl-3-hydroxybutyrate dehydrogenase was purified from the cells of baker’s yeast by streptomycin treatment, Sephadex G-50 gel filtration, SP-Sephadex C-50 chromatography, and Toyopearl HW-60F gel filtration. The purified enzyme preparation was homogeneous and the molecular weight was about 31,000 to 32,000. The enzyme was NADPH-dependent and its maximum activity was at pH 7.0 and 45°C. It was stable between pH 6 and 9. The Km values at pH 7.0 were 0.42 mM for benzyl 2-methyl-3-oxobutyrate (1) and 4.2 mM for α-methyl β-hydroxy ester [syn-(2) and anti-(3)]. This enzyme reduced only benzyl 2-methyl-3-oxobutyrate (1) but had no effect on other synthetic substrates.

The reduced products [syn-(2) and anti(3)] produced by the purified enzyme were identified by 400 MHz NMR.     

Purification and Properties of Cyclodextrin Glucanotransferase from Brevibacterium sp. No. 9605

Cyclodextrin glucanotransferase (EC 2.4.1.19) from Brevibacterium sp. No. 9605 was purified to homogeneity by chromatography on butyl-Toyopearl 650M, γ-cyclodextrin-Sepharose 4B, and Toyopearl HW-55S. The molecular weight of the purified enzyme was estimated to be 75,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point of the purified enzyme was 2.8. The optimum pH and temperature were pH 10 and 45°C, respectively. The enzyme was stable at the range of pH 6–8 and at temperatures 50°C or less in the presence of CaCl₂. The enzyme produced mainly γ-cyclodextrin from starch in the initial stage of reaction, but later, the proportion of β-cyclodextrin was increased.     

Purification and characterization of an extremely stable glucose isomerase from Geobacillus thermodenitrificans TH2

The D-glucose/D-xylose isomerase was purified from a thermophilic bacterium, Geobacillus thermodenitrificans TH2, by precipitating with heat shock and using Q-Sepharose ion exchange column chromatography, and then characterized. The purified enzyme had a single band having molecular weight of 49 kDa on SDS-PAGE. In the presence of D-glucose as a substrate, the optimum temperature and pH of the enzyme were found to be 80°C and 7.5, respectively. The purified xylose isomerase of G. thermodenitrificans TH2 was extremely stable at pH 7.5 after 96 h incubation at 4°C and 50°C. When the thermal stability profile was analyzed, it was determined that the purified enzyme was extremely stable during incubation periods of 4 months and 4 days at 4°C and 50°C, respectively. The K _m and V _max values of the purified xylose isomerase from G. thermodenitrificans TH2 were calculated as 32 mM and 4.68 μmol/min per mg of protein, respectively. Additionally, it was detected that some metal ions affected the enzyme activity at different ratios. The enzyme was active and stable at high temperatures and nearly neutral pHs which are desirable for the usage in the food and ethanol industry.     

Purification and Characterization of Thermostable Pectate Lyase with Protopectinase Activity from Thermophilic Bacillus sp. TS 47

A strain of thermophilic bacterium, Bacillus sp., with pectolytic activity has been isolated. It produced an extracellular endo-polygalacturonate trans-eliminase (PL, EC 4.2.2.1) when grown at 60°C on a medium containing polygalacturonate (PGA). The PL was purified by hydrophobic, cation exchange, and size exclusion column chromatographies. The molecular mass of the enzyme was 50 kDa by SDS-PAGE. The isoelectric point of the enzyme was pH 5.3. The enzyme had a half-life of 13 and 1 h at 65 and 70°C, respectively, and showed optimal activity around at 70°C and pH 8.0. It had protopectinase activity, besides PL activity, on lemon protopectin and cotton fibers. The first 20 amino acids sequence of the enzyme had significant similarity with that of PL from methophilic Bacillus subtilis, with 50% identity.     

Studies on Protein Metabolism in Higher Plants

A leaf protease of tobacco whose activity was enhanced during curing was purified about 60 times with ammonium sulfate fractionation, ethanol precipitation, calcium phosphate gel treatment and Sephadex G-200 column chromatography, and some properties of the protease were examined. The purified enzyme showed the optimum pH at 5.5 and the optimum temperature at 60°C. The protease activity was stable between pH 4.5 and 5.5 at 50°G or at pH 5.5 below 40°C for 1 hr, but completely destroyed at 70°C during 1 hr. The protease activity was greatly activated by reducing agents such as cysteine, glutathione or mercaptoethanol and inhibited by p-chloromercuribenzoate, phenyl- mercuric acetate or silver ions. Metal ions except for silver ion and ethylenediamine tetraacetic acid did not affect the protease activity so far examined.