Purification and properties of suppressor seryl-tRNA: ATP phosphotransferase from bovine liver

Seryl-tRNASerCmCA: ATP phosphotransferase was purified 1200-fold from bovine liver by ultracentrifugation at 150 000 X g, chromatography on DEAE-cellulose, fractional precipitation with ammonium sulfate, chromatography on hydroxyapatite, gel filtration on Sephacryl S-300 and affinity chromatography on Blue Sepharose. Molecular mass was estimated as 135-145 kDa. The Km values for ATP and ser-tRNASerCmCA were 2 mM and 21 nM, respectively. This enzyme did not react with ser-tRNASerIGA, tyr-tRNA or thr-tRNA.     

Purification and characterization of novel chondroitin ABC and AC lyases from Bacteroides stercoris HJ-15, a human intestinal anaerobic bacterium.

Two novel chondroitinases, chondroitin ABC lyase (EC 4.2.2.4) and chondroitin AC lyase (EC 4.2.2.5), have been purified from Bacteroides stercoris HJ-15, which was isolated from human intestinal bacteria with glycosaminoglycan degrading enzymes. Chondroitin ABC lyase was purified to apparent homogeneity by a combination of QAE-cellulose, CM-Sephadex C-50, hydroxyapatite and Sephacryl S-300 column chromatography with a final specific activity of 45.7 micromol.min-1.mg-1. Chondroitin AC lyase was purified to apparent homogeneity by a combination of QAE-cellulose, CM-Sephadex C-50, hydroxyapatite and phosphocellulose column chromatography with a final specific activity of 57.03 micromol.min-1.mg-1. Chondroitin ABC lyase is a single subunit of 116 kDa by SDS/PAGE and gel filtration. Chondroitin AC lyase is composed of two identical subunits of 84 kDa by SDS/PAGE and gel filtration. Chondroitin ABC and AC lyases showed optimal activity at pH 7.0 and 40 degrees C, and 5.7-6.0 and 45-50 degrees C, respectively. Both chondroitin lyases were potently inhibited by Cu2+, Zn2+, and p-chloromercuriphenyl sulfonic acid. The purified Bacteroidal chondroitin ABC lyase acted to the greatest extent on chondroitin sulfate A (chondroitin 4-sulfate), to a lesser extent on chondroitin sulfate B (dermatan sulfate) and C (chondroitin 6-sulfate). The purified chondroitin AC lyase acted to the greatest extent on chondroitin sulfate A, and to a lesser extent on chondroitin C and hyaluronic acid. They did not act on heparin and heparan sulfate. These findings suggest that the biochemical properties of these purified chondroitin lyases are different from those of the previously purified chondroitin lyases.     

Purification and properties of pig liver kynureninase.

Kynureninase [L-kynurenine hydrolase, EC 3.7.1.3] was purified from pig liver by a procedure including DEAE-cellulose chromatography, hydroxyapatite chromatography, ammonium sulfate fractionation, DEAE-Bio Gel chromatography, Sephacryl S-200 gel filtration, kynurenine-Sepharose affinity chromatography, and Sephadex G-200 gel filtration. The enzyme was found to be homogeneous by the criterion of disc-gel electrophoresis. The enzyme has a molecular weight of about 100,000 and exhibits absorption maxima at 280 and 420 nm. The optimum pH and the isoelectric point of the enzyme are 8.5 and 5.0, respectively. The Michaelis constants were determined to be as follows: L-kynurenine, 7.7 X 10(-4) M; L-3-hydroxykynurenine, 1.3 X 10(-5) M; and pyridoxal 5'-phosphate, 1.8 X 10(-6) M. L-3-Hydroxykynurenine is hydrolyzed more rapidly than L-kynurenine; the liver enzyme can be regarded as a 3-hydroxy-kynureninase.     

N-acetyl-beta-D-hexosaminidase secreted by the marine fungus Phoma glomerata

Among the ten strains of marine fungi studied, the mycelial fungus Phoma glomerata showed maximum potency in producing N-acetyl-beta-D-glucosaminidase. The conditions for fungal growth and enzyme biosynthesis were evaluated. N-acetyl-beta-D-hexosaminidase was isolated from the culture liquid of Phoma glomerata by ion-exchange chromatography (on DEAE-cellulose and DEAE-Sephacell) and gel filtration (on Toyopearl HW-55) with a yield of 35%; the enzyme, purified 36.4-fold, had a molecular weight of 20 kDa. The homogeneity of the enzyme was confirmed by gel filtration and SDS-PAGE. Transglycosylation reactions catalyzed by the enzyme produced N-acetyl-D-glucosamine and N-acetyl-D-galactosamine with respective yields of 38 and 46%.     

Cell wall proteins from sugar beet cells in suspension culture

Several proteins were extracted from the purified cell walls of suspension-cultured sugar beet cells with 0.5% EDTA (pH 6.8) after prior extraction of the walls with 0.5% deoxycholate and then with 2 molar NaCl. Two abundant proteins (P-I and P-II protein) were separately purified to homogeneity by procedures that included fractionation with ammonium sulfate, column chromatography on DEAE-cellulose and butyl Toyopearl, and preparative polyacrylamide electrophoresis. P-I exists as a dimer of identical subunits, and P-II is composed of four different subunits. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that quite different polypeptides are present in the culture medium and in the NaCl and EDTA extracts of the wall.     

Hypoxanthine-DNA glycosylase from Escherichia coli. Partial purification and properties

Hypoxanthine-DNA glycosylase from Escherichia coli was partially purified by ammonium sulfate fractionation and by chromatography on Sephacryl S-200, DEAE-cellulose, and phosphocellulose P-11 columns. Analysis of the enzymatic reaction products was carried out on a minicolumn of DEAE-cellulose and/or by paper chromatography, by following the release of the free base [3H]hypoxanthine from [3H]dIMP-containing phi X174 DNA. In native conditions, the enzyme has a molecular mass of 60 +/- 4 kDa, as determined by gel filtration on Sephadex G-150 and Sephacryl S-200 columns. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed a major polypeptide band of an apparent molecular mass of 56 kDa, and glycerol gradient centrifugation indicated a sedimentation coefficient of 4.0 S. Hypoxanthine-DNA glycosylase from E. coli has an obligatory requirement for Mg2+ and is totally inhibited in the presence of EDTA. Co2+ can only partially replace Mg2+. The enzyme is inhibited by hypoxanthine which at 4 mM causes 85% inhibition. The optimal pH range of the enzymatic activity is 5.5-7.8, and the apparent Km value is 2.5 x 10(-7) M.     

Purification, characterization, and molecular cloning of a thermostable superoxide dismutase from Thermoascus aurantiacus

A thermostable superoxide dismutase [(SOD) EC 1.15.1.1] from a Thermoascus aurantiacus var. levisporus was purified to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) homogeneity by a series of column chromatographies. The molecular mass of a single band of the enzyme was estimated to be 16.8 kDa by SDS-PAGE. The molecular mass was estimated to be 33.2 kDa by gel filtration on Sephacryl S-100, indicating that the enzyme was composed of two identical subunits of 16.8 kDa each. N-terminal amino acid sequencing (seven residues) yielded VKAVAVL. Using RACE-PCR, a Cu, Zn-SOD gene was cloned from T. aurantiacus var. levisporus. The sequence was 705 bp and contained a 468 bp ORF encoding a Cu, Zn-SOD of 155 amino acid residues.     

Polyamine synthesis in plants: isolation and characterization of spermidine synthase from soybean (Glycine max) axes

Spermidine synthase (EC 2.5.1.16) was purified to homogeneity for the cytosol of soybean (Glycine max) axes using ammonium sulfate fractionation and chromatography on DEAE-Sephacel, Sephacryl S-300, omega-aminooctyl-Sepharose and ATPA-Sepharose. The molecular mass of the enzyme estimated by gel filtration and SDS-PAGE is 74 kDa. Cadaverin and 1,6-diaminohexane could not replace putrescine as the aminopropyl acceptor. Kinetic behaviors of the substrate are consistent with a ping pong mechanism. The kinetic mechanism is further supported by direct evidence confirming the presence of an aminopropylated enzyme and identification of product, 5'-deoxy-5'-methylthioadenosine, prior to adding putrescine. The Km values for decarboxylated S-adenosylmethionine and putrescine are 0.43 microM and 32.45 microM, respectively. Optimum pH and temperature for the enzyme reaction are 8.5 and 37 degrees C, respectively. The enzyme activity is inhibited by N-ethylmaleimide and DTNB, but stimulated by Co2+, Cu2+ and Ca2+ significantly, suggesting that these metal ions could be the cellular regulators in polyamine biosynthesis.     

Amino acid activation in mammalian brain. Purification and characterization of tryptophan-activating enzyme from buffalo brain

l-Tryptophan-activating enzyme [l-tryptophan-tRNA ligase (AMP), EC 6.1.1.2] of water-buffalo brain was purified to near homogeneity by heat and pH treatments, ammonium sulphate fractionation, column chromatography on DEAE-cellulose, hydroxyapatite and Amberlite CG-50, and gel filtration on Sephadex G-200. The purified enzyme catalyses tryptophanyl-tRNA formation with yeast tRNA, but not with Escherichia coli tRNA. The enzyme exhibits multiple peaks of activity in Sephadex gel filtration with molecular weights corresponding to 155000, 105000 and 50000. However, only one peak of activity with molecular weight of 155000 can be detected when the enzyme is subjected to gel filtration at high concentration. Disc gel electrophoresis in the presence of sodium dodecyl sulphate reveals a single band with molecular weight of 55000. The activity of the enzyme is concentration dependent. Different K(m) and V(max.) values are obtained at different enzyme concentrations. These data suggest that this enzyme may exist in different quaternary structures, each with its own kinetic constants. The enzyme activity is inhibited by p-chloromercuribenzoate, and is not protected by the presence of the substrates, l-tryptophan, Mg(2+), ATP, in any combination.     

Purification and characterization of ginsenoside Rb1-metabolizing beta-glucosidase from Fusobacterium K-60, a human intestinal anaerobic bacterium.

Fusobacterium K-60, a ginsenoside Rb1-metabolizing bacterium, was isolated from human intestinal feces. From this Fusodobacterium K-60, a ginsenoside Rb1-metabolizing enzyme, beta-glucosidase, has been purified. The enzyme was purified to apparent homogeneity by a combination of butyl-Toyopearl, hydroxyapatite ultragel, Q-Sepharose, and Sephacryl S-300 HR column chromatographies with a final specific activity of 1.52 micromol/min/mg. It had optimal activity at pH 7.0 and 40 degrees C. The molecular mass of this purified enzyme was 320 kDa, with 4 identical subunits (80 kDa). The purified enzyme activity was inhibited by Ba++, Fe++, and some agents that modify cysteine residues. This enzyme strongly hydrolyzed sophorose, followed by p-nitrophenyl beta-D-glucopyranoside, esculin, and ginsenoside Rb1. However, this enzyme did not change 20-O-beta-D-glucopyranosyl-20(S)-protopanaxadiol (IH-901) to 20(S)-protopanaxadiol, while it weakly changed ginsenoside Rb1 to IH-901. These findings suggest that the Fusobacterial beta-glucosidase is a novel enzyme transforming ginsenoside Rb1.     

Purification and properties of thermostable xylanase and beta-xylosidase produced by a newly isolated Bacillus stearothermophilus strain.

We isolated a thermophilic bacterium that produces both xylanase and beta-xylosidase. Based on taxonomical research, this bacterium was identified as Bacillus stearothermophilus. Each extracellular enzyme was separated by hydrophobic chromatography by using a Toyopearl HW-65 column, followed by gel filtration with a Sephacryl S-200 column. Each enzyme in the culture was further purified to homogeneity (62-fold for xylanase and 72-fold for beta-xylosidase) by using a fast protein liquid chromatography system with a Mono Q HR 5/5 column. The optimum temperatures were 60 degrees C for xylanase and 70 degrees C for beta-xylosidase. The isoelectric points and molecular masses were 5.1 and 39.5 kDa for xylanase and 4.2 and 150 kDa for beta-xylosidase, respectively. Heat treatment at 60 degrees C for 1 h did not cause inhibition of the activities of these enzymes. The action of the two enzymes on xylan gave only xylose.     

Lysophospholipase L1 from Escherichia coli K-12 overproducer

After screening 900 E. coli strains of the Clarke and Carbon collection for by lysophospholipase L1 activities, we isolated a clone bearing the plasmid pLC6-34, which showed an increased level of lysophospholipase L1 activity. Strains bearing the plasmid pC124, a subclone of pLC6-34 in plasmid vector pUC8, showed approximately 11.4 times higher lysophospholipase L1 activity than that of the parental strain. Starting from those overproducing strains, the lysophospholipase L1 was purified to near homogeneity by sequential use of ammonium sulfate fractionation, Sephacryl S-300, DEAE-cellulose, hydroxyapatite and Sephacryl S-200 column chromatographies. The apparent molecular weight of the purified lysophospholipase L1 was estimated to be 20,500-22,000 both by SDS-polyacrylamide gel electrophoresis and by gel permeation chromatography. The specific activity of the homogeneous lysophospholipase L1 was 10,400 nmol/min/mg protein when 1-acyl-sn-glycero-3-phosphoethanolamine was used as the substrate. The amino acid sequence of the amino-terminal portion of purified lysophospholipase L1 was determined and was different from that of lysophospholipase L2, which had previously been purified from the envelope fraction of E. coli strains bearing its cloned structural gene, pldB [Karasawa, K., Kudo, I., Kobayashi, T., Sa-eki, T., Inoue, K., & Nojima, S. (1985) J. Biochem, 98, 1117-1125]. The gene responsible for overproduction of lysophospholipase L1 activity was designated as pldC (phospholipid degradation C). Its restriction enzyme map was also different from that of cloned pldB. These results further confirmed that, in E. coli, there are two lysophospholipases with distinct characteristics.     

Production and purification of a calcium-dependent protease from Bacillus cereus BG1

The production and purification of a calcium-dependent protease by Bacillus cereus BG1 were studied. The production of the protease was found to depend specifically on the calcium concentration in the culture medium. This suggests that this metal ion is essential for the induction of protease production and/or stabilisation of the enzyme after synthesis. The calcium requirement is highly specific since other metal ions (such as Mg²⁺ and Ba²⁺, which both activate the enzyme) are not able to induce protease production. The most appropriate medium for growth and protease production comprises (g L^–1) starch 5, CaCl₂ 2, yeast extract 2, K₂HPO₄ 0.2 and KH₂PO₄ 0.2. The protease of BG1 strain was purified to homogeneity by ultrafiltration, heat treatment, gel filtration on Sephacryl S-200, ion exchange chromatography on DEAE-cellulose and, finally, a second gel filtration on Sephacryl S-200, with a 39-fold increase in specific activity and 23% recovery. The molecular weight was estimated to be 34 kDa on SDS-PAGE. The optimum temperature and pH of the purified enzyme were determined to be 60°C and 8.0, respectively, in 100 mM Tris-HCl buffer + 2 mM CaCl₂.     

L-asparaginase of Thermus thermophilus: Purification,properties and identificaation of essential amino acids for its catalytic activity

L-asparaginase EC 3.5.1.1 was purified to homogeneity from Thermus thermophilus. The apparent molecular mass of L-asparaginase by SDS-PAGE was found to be 33 kDa, whereas by its mobility on Sephacryl S-300 superfine column was around 200 kDa, indicating that the enzyme at the native stage acts as hexamer. The purified enzyme showed a single band on acrylamide gel electrophoresis with pI = 6.0. The optimum pH was 9.2 and the Km for L-asparagine was 2.8 mM. It is a thermostable enzyme and it follows linear kinetics even at 77°C. Chemical modification experiments implied the existence of histidyl, arginyl and a carboxylic residues located at or near active site while serine and mainly cysteine seems to be necessary for active form.     

胞外青霉素酰化酶的纯化及部分理化性质

巨大芽孢杆菌产胞外青霉素酰化酶发酵液经硫酸铵分级抽提及ＳｅｐｈａｄｅｘＧ－１００、羟基磷灰石、ＤＥＡＥ纤维素ＤＥ５２等层析步骤,提纯了青霉素酰化酶,得到电泳均一的酶制剂。纯酶比活力约为２５Ｕ／ｍｇ蛋白,纯化４９倍,活力回收５８％,经ＰＡＧＥ及ＳＤＳ－ＰＡＧＥ测知该酶不含亚基,其分子量约为１４０ｋＤ。该酶最适ｐＨ为９．０,最适温度４７℃,用底物ＮＩＰＡＢ测活,其Ｋｍ值为６．２×１０~（－４）ｍｏｌ／Ｌ,Ｖｍ值为１．２４×１０４ｍｏｌ／Ｌ。此外还探讨了部分金属离子对该酶的影响。     

An extracellular β-galactosidase secreted from cell suspension cultures of carrot. Its purification and involvement in cell wall-polysaccharide hydrolysis

β-Galactosidase (β-Galase, EC 3.2.1.23) activity has been detected in a culture medium of cell suspension cultures of carrot ( Daucus carota L. cv. Kintoki). The extracellular β-Galase (β-Galase-II) was purified to electrophoretic homogeneity from the concentrated medium using ammonium sulfate precipitation, chromatography on CM-Sephadex C-50. DEAE-Sepharose CL-6B and Sephacryl S-200HR, and preparative PAGE. The molecular mass of the purified enzyme was estimated to be 65 kDa by Sephacryl S-200HR gel-permeation, and 60 kDa by SDS-PAGE after treatment with SDS and 2-mercaptoethanol. The pI was 6.5. The K_m and V_max values for p -nitrophenyl (PNP)-β-D-galactopyranoside were 0.17 m M and 31.9 μmol (mg protein)^-1, h^-1, respectively. The optimal activity in McIlvaine's buffer occurred at pH 4.0–4.4. The enzyme activity was inhibited by Co²⁴, Cu²⁺, Hg^2-, p -chloromercuribenzoate (PCMB) and D-galactono-1,4-lactone. The enzyme acted on citrus galactan and larchwood arabinogalactan in an exo-fashion, and was slightly involved in the hydrolysis of an acidic pectic polymer containing arabinosyl and galactosyl residues and in the breakdown of cell walls isolated from carrot cell cultures.     

Purification of NADPH-linked alpha,beta-ketoalkene double bond reductase from rat liver

NADPH-linked alpha,beta-ketoalkene double bond reductase was purified from rat liver cytosol by fractionation with ammonium sulfate, and chromatography with DEAE-cellulose. AF-Blue Toyopearl and hydroxyapatite. The purified enzyme was homogeneous by the criterion of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be 39,500 by the electrophoresis and by HPLC gel filtration on a TSK gel G3000 SWXL column. The double bond of 2-alkenals was also reduced by the enzyme, but to a lesser extent. The enzyme activity was inhibited by 5,5'-dithiobis(2-nitrobenzoic acid), p-chloromercuribenzoic acid, N-ethylmaleimide, iodoacetamide, dicumarol, quercitrin, and disulfirum. However, the enzyme was insensitive to oxygen.     

Glutamate synthase from rice leaves

Ferredoxin-dependent glutamate synthase (EC 1.4.7.1) from rice leaves (Oryza sativa L. cv Delta) was purified 206-fold with a final specific activity of 35.9 mumoles glutamate formed per min per milligram protein by a procedure including ammonium sulfate fractionation, DEAE-cellulose chromatography, Sephacryl S-300 gel filtration, and ferredoxin-Sepharose affinity chromatography. The purified enzyme yielded a single protein band on polyacrylamide gel electrophoresis. Molecular weight of the native enzyme was estimated to be 224,000 daltons by Sepharose 6B gel filtration. Electrophoresis of the dissociated enzyme in sodium dodecyl sulfate-polyacrylamide gel gave a single protein band which corresponds to the subunit molecular weight of 115,000 daltons. Thus, it is concluded that the glutamate synthase is composed of two polypeptidic chains exhibiting the same molecular weight. Spectrophotometric analysis indicated that the enzyme is free of iron-sulfide and flavin. The pH optimum was 7.3. The enzyme had a negative cooperativity (Hill number of 0.70) for glutamine, and its K(m) value increased from 270 to 570 mum at a glutamine concentration higher than 800 mum. K(m) values for alpha-ketoglutarate and ferredoxin were 330 and 5.5 mum, respectively. Asparagine and oxaloacetate could not be substituted for glutamine and alpha-ketoglutarate, respectively. Enzyme activity was not detected with pyridine nucleotides as electron donors. Azaserine and several divalent cations were potent inhibitors. The purified enzyme was stabilized by dithiothreitol.     

Purification and subunit structure of recBC DNase from Escherichia coli harboring a recB and recC genes-inserted plasmid

recBC DNase of Escherichia coli has been purified from the transformant, HB101/pFS11-04 (recB+ recC+), by successive ammonium sulfate fractionation, DEAE-cellulose chromatography, Sephadex G-150 gel filtration, hydroxyapatite chromatography, DNA cellulose affinity chromatography, and second DEAE-cellulose chromatography. The purified enzyme was obtained in an overall yield of 3%. The enzyme protein appeared as a single pure component on native polyacrylamide gel electrophoresis. The purified enzyme was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and two-dimensional electrophoresis. The results show that recBC DNase consists of two nonidentical subunits with molecular weights of 125,000 and 135,000, and isoelectric points of 5.6 and 5.7, respectively.     

Impairment of IGF-I gene splicing and MGF expression associated with muscle wasting

An aminopeptidase was purified from bovine skeletal muscle by ammonium sulfate fractionation and by successive chromatographies of DEAE-cellulose, Sehacryl S-200, phenyl-sepharose CL-4B, hydroxyapatite and Hi-Trap chelating HP columns. The aminopeptidase was purified about 14-fold over the crude extract with a yield of 1.0% activity. The molecular mass of the enzyme was found to be 58 kDa on SDS-PAGE. The enzyme activity was enhanced by the addition of some anions, such as Cl(-), NO(3)(-) and SCN(-), which is the most unique property of this enzyme. While, the activity was strongly inhibited by bestatin, PMSF and puromycin, suggesting that it was a serine protease. In addition, this enzyme was identical with leukotriene (LT) A4 hydrolase, converting LTA4 to LTB4.