Purification and characterisation of leukotriene A4 hydrolase from rat neutrophils

Leukotriene A₄ hydrolase was rapidly and extensively purified from rat neutrophils using anion exchange and gel filtration high-pressure liquid chromatography. The enzyme which converts the allylic epoxide leukotriene A₄ to the 5,12-dihydroxyeicosatetraenoic acid leukotriene B₄ was localized in the cytosolic fraction and exhibited an optimum activity at pH 7.8 and apparent K_m for leukotriene A₄ between 2 · 10^?5 and 3 · 10^?5 M. The purified leukotriene A₄ hydrolase was shown to have a molecular weight of 68 000 on sodium dodecylsulfate polyacrylamide gel electrophoresis and of 50 000 by gel filtration. The molecular weight and monomeric native form of this enzyme are unique characteristics which distinguish leukotriene A₄ hydrolase from previously purified epoxide hydrolases.     

Purification of the activating enzyme for the Fe-protein of nitrogenase from Azospirillum brasilense

The activating enzyme for the Fe-protein of nitrogenase from Azospirillum brasilense has been purified to near homogeneity. The procedure includes ion-exchange chromatography, chromatofocusing and gel filtration. The M_r of the purified enzyme was determined to be 33 500 on SDS-polyacrylamide gel electrophoresis. The purified enzyme was compared with the acticating enzyme from Rhodospirillum rubrum.     

Partial purification and properties of diacylglycerol kinase from rat liver cytosol

Diacylglycerol:ATP kinase(EC 2.3.1.-) was highly purified (more than 2000-fold) from rat liver cytosol. The specific activity of the obtained enzyme was about 1.5 μmol phosphatidate formed/mg of protein/min. The purification procedures included ammonium sulfate fractionation, DEAE-cellulose chromatography, gel filtration on Sephadex G-200, and finally affinity chromatography on ATP-agarose. The activities of diacylglycerol:GTP kinase and monoacylglycerol:ATP kinase were copurified throughout the procedures, forming a single peak together with diacylglycerol: ATP kinase. Furthermore, these kinase activities showed a single peak when the highly purified enzyme was analyzed by a sucrose density gradient centrifugation and polyacrylamide gel electrophoresis. The three kinase activities are, therefore, most likely catalyzed by a single enzyme. The kinase showed an apparent molecular weight of 121,000 on gel filtration and sedimented at 5.1 S in a sucrose gradient centrifugation. The apparent K_m values were 170 μm for ATP, 540 μm for GTP, and 3.0 μm for diacylglycerol. A number of nucleoside triphosphates and diphosphates competitively inhibited the kinase, in particular the activity utilizing GTP. Among the nucleotides tested, ADP was the most potent inhibitor (the apparent K_i:50 μm for diacylglycerol:ATP kinase and 42 μm for diacylglycerol:GTP kinase). The kinase required Mg²⁺ and deoxycholate for its activity, and the optimal pH was 8.0–8.5. No dependence on added phospholipids was observed.     

Isolation of the two components of Condylactis toxin.

The two toxic components from the sea anemone Condylactis gigantea have been isolated and purified using gel filtration, ion-exchange chromatography, and preparative isoelectric focusing. The molecular weight of both components is estimated by gel filtration to be 4500. The isoelectric points of the two toxins were determined to be 4.8 and 5.8 with LD₅₀ values of 19 and 58 μg/kg, respectively, when injected into Armadillidium vulgare, a terrestrial crustacean. Low-level labeling with ¹²⁵I using lactoperoxidase was effected for the purpose of estimating homogeneity.     

Degradation of RNA in rat reticulocytes. II. Relationship between RNase and its corresponding inhibitor in rat reticulocyte

A latent RNase was partially purified by ammonium sulfate fractionation and Sephadex G-75 gel filtration from rat reticulocyte lysate. By mixing free RNase and its inhibitor in vitro, the latent RNase was shown to be a complex of each component. The latent RNase was activated by SH reagents, but no dissociation of the complex was observed. It was also activated by 6 m urea and 0.1 m H₂SO₄, and in these cases the enzyme was released as judged by gel filtration. From the results of this and precious paper, a possible mechanism of the regulation of RNase activity in rat reticulocyte is discussed.     

Characterization and purification of a kallikrein from human pancreatic juice and immunological comparison with other kallikreins.

A prekallikrein has been demonstrated in human pancreatic juice and the active enzyme has been purified from this material. The purification procedure included filtration on Sephadex G-100, chromatography on DEAE-cellulose and affinity chromatography on trypsin-inhibitor Sepharose. The purified kallikrein appeared to be homogeneous by polyacrylamide gel electrophoresis at pH 8.3 and by immunoelectrophoresis. Human pancreatic kallikrein is immunologically different from human plasma kallikrein and from pancreatic kallikreins of other species (hog, cat, rat and dog). Human pancreatic kallikrein has common antigenic determinants with human urinary and submandibular kallikreins but probably not with parotid kallikrein.     

Purification and properties of malonyl-CoA decarboxylase from rat liver mitochondria and its immunological comparison with the enzymes from rat brain, heart, and mammary gland.

Malonyl-CoA decarboxylase (EC 4.1.1.9) was found to be localized in the mitochondria in rat liver. Low ionic strength (10 mm Na phosphate) buffer extracted the bulk (>85%) of the enzyme from the mitochondria. From this extract the enzyme was purified over 2,000-fold using a combination of (NH₄)₂SO₄ precipitation, gel filtration with Sepharose 4B and Sephadex G-150, ion exchange chromatography with QAE-Sephadex and CM-Sephadex, and finally chromatography on NADP-agarose. The purified enzyme, which had a specific activity of about 16 μmol/min/mg, appeared to be electrophoretically homogeneous and had a molecular weight of 160,000. The decarboxylase had a broad pH optimum between 8.5 and 10.0 and showed a typical Michaelis-Menten substrate saturation pattern from which K_m and V were calculated to be 54 μm and 18.8 μmol/min/mg, respectively. This enzyme decarboxylated neither malonic acid nor methylmalonyl-CoA and was severely inhibited by thiol-directed reagents such as p-hydroxymercuribenzoate and N-ethylmaleimide but not by iodoacetamide. Acetyl-CoA, propionyl-CoA, and methylmalonyl-CoA also inhibited the enzyme. The purified decarboxylase was immunogenic in rabbits and Ouchterlony double diffusion analysis revealed a single precipitant line with the purified enzyme. The IgG fraction isolated from the antiserum inhibited the enzyme from not only liver mitochondria but also the mammary gland, heart, and kidney of the rat. However, malonyl-CoA decarboxylase from rat brain mitochondria was not inhibited by the antibody. Malonyl-CoA decarboxylase purified from the uropygial gland of a domestic goose neither cross reacted nor was it inhibited by the antiserum prepared against the rat liver mitochondrial enzyme and the antibody against the goose enzyme neither cross-reacted nor inhibited the enzyme from the rat. It is proposed that a role for mitochondrial malonyl-CoA decarboxylase is to decarboxylate malonyl-CoA generated by propionyl-CoA carboxylase and thus protect mitochondrial enzymes susceptible to inhibition by malonyl-CoA.     

Purine nucleoside phosphorylases purified from rat liver and Novikoff hepatoma cells.

Purine nucleoside phosphorylase (PNP) was purified from rat hepatoma cells and normal liver tissue utilizing the techniques of ammonium sulfate fractionation, heat treatment, ion-exchange and molecular exclusion chromatography, and polyacrylamide gel electrophoresis. Homogeneity was established by disc gel electrophoresis in the presence and absence of sodium dodecyl sulfate. Purified rat hepatoma and liver PNPs appeared to be identical with respect to subunit and native molecular weight, substrate specificity, heat stability, kinetics and antigenic identity. A native molecular weight of 84,000 was determined by gel filtration. A subunit molecular weight of 29,000 was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A single isoelectric point was observed at pH 5.8, and the pH optimum was 7.5. Inosine, guanosine, xanthosine, and 6-mercaptopurine riboside were substrates for the enzymes. The apparent K_m for both inosine and guanosine was about 1.0 × 10^?4m and for phosphate was 4.2 × 10^?4m. Hepatoma and liver PNP showed complete cross-reactivity using antiserum prepared against the liver enzyme.     

Author index

The membrane-bound ATPase activity of Bacillus subtilis was inhibited by dicyclohexylcarbodiimide (DCCD). The DCCD-reactive proteolipid of B. subtilis was extracted, from labelled or untreated membranes containing F₁ or depleted of F₁, with neutral or acidic chloroform/methanol. Purification of the [₁₄C]DCCD-binding proteolipid was attempted by column chromatography on methylated Sephadex G-50 and on DEAE-cellulose. The maximal amount of DCCD which could be bound to the purified proteolipid was found to exceed the amount bound by the purified proteolipid extracted from membranes labelled with the lowest [₁₄C]DCCD concentration required for maximal inhibition of the membrane-bound ATPase activity. The radioactive protein peaks eluted by gel filtration and ion-exchange chromatography were analysed by urea-SDS polyacrylamide slab gel electrophoresis and autoradiography. Radioactivity was incorporated into two components of M_r 18 000 and 6000 when proteolipid was purified by methylated Sephadex. The 6000 polypeptide was always present, whatever the extraction and purification procedures. However, the 18 000 polypeptide was present in largest quantity only when proteolipid was extracted from membranes containing F₁ and purified by methylated Sephadex. When proteolipid was purified on DEAE-cellulose this [₁₄C]DCCD binding component of M_r 18 000 was absent.     

Purification of a proteinase and proteinase inhibitor from Tetrahymen a pyriformis

• 1.1. A cysteine proteinase and cysteine proteinase inhibitor have been purified from Tetrahymena.
• 2.2. The proteinase was purified by ammonium sulphate fractionation, gel filtration, ion exchange chromatography and affinity chromatography, and appeared homogeneous by gel filtration and electrophoresis (mol. wt approx 28,000). It hydrolysed BAPNA, degraded azocasein, and converted 80S ribosomes to subunits. Thiol reagents inhibited these activities.
• 3.3. The inhibitor was purified by heat treatment, ammonium sulphate fractionation and ion exchange chromatography, and appeared homogeneous by gel filtration and electrophoresis (mol. wt approx 12.500). The inhibitor was heat stable and it inhibited papain, as well as the Tetrahymena proteinase.

     

Purification and subunit structure of mouse liver cystathionase

Cystathionase has been purified from mouse liver by ammonium sulfate precipitation, ethanol precipitation, column chromatography on DEAE-cellulose and on hydrox-ylapatite, as well as Sephadex G-200 gel filtration. These procedures yielded a chromatographically homogeneous enzyme which was purified more than 1000-fold relative to whole liver extract. Overall recovery was approximately 4%. The purified enzyme does not contain detectable carbohydrate and migrates as a single protein component on analytical disc gel electrophoresis. A sedimentation coefficient of 8.3 S has been determined for the active enzyme by rate zonal centrifugation in glycerol gradients. This value suggests a molecular weight for the native enzyme of approximately 160,000 g/mol, a value similar to that estimated by gel filtration. Following sodium dodecyl sulfate gel electrophoresis in the presence of reducing agent and at different gel concentrations, a single protein component with a molecular weight of 40,000 g/mol was obtained. Thus, the enzyme appears to consist of four subunits of equal size. The K_m value for cystathionine at pH 8.1, 37 °C, and in the presence of 1 mm dithioerythritol is approximately 1 mm.     

Preparation and properties of concanavalin A-binding glycopeptides derived from rat brain glycoproteins

Mannose-rich glycopeptides derived from brain glycoproteins were recovered by affinity chromatography on Concanavalin A-Sepharose. These glycopeptides, which adsorb to the lectin and are eluted with α-methylmannoside, constitute about 25–30% of the total glycopeptide material recovered from rat brain glycoproteins. They contain predominately mannose and N-acetylglucosamine (mannose/N-acetylglucosamine = 3), as well as small amounts of galactose and fucose. Approx. 65% of the Concanavalin A-binding glycopeptide carbohydrate was recovered after treatment with leucine aminopeptidase, gel filtration on Biogel P-4, and ion-exchange chromatography on coupled Dowex 50-hydrogen and Dowex 1-chrolide columns. The purified glycopeptide fraction contained six mannose and two N-acetylglucosamine residues per aspartic acid and possessed an apparent molecular weight of about 2000 as assessed by gel filtration and amino acid analysis. Galactose and fucose were absent. Treatment of the purified glycopeptides with α-mannosidase drastically reduced their affinity for Concanavalin A, suggesting the presence of one or more terminal mannose residues.     

Isolation of an N-acetyl-d-galactosamine-binding protein from winged bean (Psophocarpus tetragonolobus)

A lectin has been purified to homogeneity by affinity chromatography on a Sepharose-N-caproyl-d-galactosamine column from the local variety of winged bean (Psophocarpus tetragonolobus). The lectin agglutinated native erythrocytes of all blood groups. This hemagglutination was inhibited best by N-acetyl-d-galactosamine. A molecular weight of 41,000 was obtained for the lectin by gel filtration on Bio-Gel P-100. Sodium dodecyl sulfate-polyacryl-amide gel electrophoresis of the same lectin showed a single M_r 35,000 polypeptide.     

Purification and Partial Characterization of a Genetically-Defined Superoxide Dismutase (SOD-1) Associated with Maize Chloroplasts

The chloroplast-associated form of superoxide dismutase from maize (Zea mays L.) (SOD-1) has been purified by a stepwise procedure consisting of (NH₄)₂SO₄ fractionation, G-100 Sephadex gel filtration, DEAE-Sephacel chromatography, and hydroxylapatite chromatography. This procedure resulted in a single band on sodium dodecyl sulfate-polyacrylamide gels indicating that the preparation is homogeneous. The holoenzyme molecular weight was estimated at 31,000 to 33,000 by gel filtration. The subunit molecular weight of this dimeric protein was estimated at 14,500 on sodium dodecyl sulfate-polyacrylamide gels. Studies involving amino acid composition analysis, immunological cross-reactivity, in vitro subunit hybridizations, and H₂O₂ sensitivity indicate that SOD-1 differs significantly from SOD-2 and SOD-4, the other cupro-zinc forms of SOD from maize. The possible physiological role of SOD-1 within the chloroplast is discussed.     

Evidence for the occurrence of calmodulin in the yeasts Candida albicans and Saccharomyces cerevisiae

The lectin extracted from Vicia graminea seeds has been purified by conventional techniques but such procedures did not give a satisfactory yield. We describe a new purification which involves 3 steps after obtention of the crude extract. The first step is based on affinity chromatography on con A—Sepharose. Further purification steps were performed on DEAE-Sephacel chromatography and ultrogel AcA₄₄ gel filtration. The homogeneity of the lectin was demonstrated by polyacrylamide gel electrophoresis. Purification of the lectin by this new method was less time consuming, the yield was higher and the specific activity increased.     

Purification and characterization of L-mimosine synthase from Leucaena leucocephala

L-Mimosine synthase has been isolated from Leucaena leucocephala seedlings and purified 280-fold by heat treatment, ammonium sulphate fractionation, gel filtration and ion-exchange chromatography. The enzyme was shown to be homogeneous by gel electrophoresis (MW 64 000±2000) and to consist of two identical subunits with MWs of 32 000±2000. The purified enzyme has a K_m value of 6.25 x 10^?3 M for O-acetyl-L-serine and 5.0 x 10^?3 M for 3,4-dihydroxypyridine. In these and other properties, the enzyme differs from β-(pyrazol-1-yl)-L-alanine synthase from Citrullus vulgaris seedlings.     

Purification of the toxic protein from Bacillus thuringiensis serotype 10 isolate demonstrating a preferential larvicidal activity to the mosquito

The protein demonstrating larvicidal activity to the mosquito Aedes aegypti was purified from the alkali extract of the spore-parasporal inclusion complex of the isolate, 73-E-10-2, belonging to Bacillus thuringiensis serotype 10. By Sepharose CL-4B gel filtration and DEAE-cellulose column chromatography, a toxic protein was obtained, and its homogeneity was confirmed by Sephadex G-150 gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of the toxic protein was 67,000, when estimated by SDS-PAGE. The LC₅₀ of the toxic protein against 4-day-old larvae of A. aegypti was 16.8 μg/ml. There was no serological relationship between the toxic protein from the isolate 73-E-10-2 and that (M_r 67,000) from the type strain of B. thuringiensis subsp. israelensis.     

Urease of Spirulina maxima

Urease (EC 3.5.1.5) was purified from Spirulina maxima by ammonium sulfate precipitation, DEAE-cellulose chromatography and gel filtration on Sephadex G-200. The enzyme had maximum activity at pH 8.7, a K_m for urea of 0.12 mM and a MW of ca 232 000. A MW of 38 000 was determined for the subunits. The enzyme was inactivated by p-hydroxymercuribenzoate.     

Purification of ctp: cholinephosphate cytidylyl-transferase from pea stems

CTP:cholinephosphate cytidylyltransferase (EC 2.7.7.15) was purified from pea (Pisum sativum) stems. The purification involved ammonium sulphate fractionation, ion exchange chromatography, removal of proteases with α₂-macroglobulin and gel filtration. The purified enzyme had K_m values for phosphorylcholine and CTP of 2.1 mM and 0.55 mM respectively. It was found to have a pH optimum of 7.5, a requirement for Mg²⁺ and an M_r of 56000. It could not utilize phosphorylethanolamine and its activity was not stimulated by added phospholipids.     

Purification of the creatine kinase isozymes of the green sunfish (Lepomis cyanellus) with Blue Sepharose CL-6B.

Three homodimeric creatine kinase isozymes (A₂, B₂, and C₂) of the green sunfish (Lepomis cyanellus) were purified by a combination of affinity chromatography, gel filtration, and preparative starch gel electrophoresis. The final preparations were isozymically pure and were used to elicit antibodies in rabbits. The use of the group-specific adsorbant Blue Sepharose CL-6B (Pharmacia) and specific elution conditions for creatine kinase facilitated purification. Fish creatine kinase isozymes are sensitive to denaturation and cannot be readily purified by procedures routinely used for mammalian creatine kinase isozymes.