Purification and properties of a monoacylglycerol lipase in human erythrocytes

A membrane-bound monoacylglycerol lipase (MAGL) activity, previously demonstrated in intact human erythrocytes [Boyer, Somma, Vérine, L'Hôte, Finidori, Merger and Arnaud (1981) J. Clin. Endocrinol. Metab. 53, 143-148], has now been purified to apparent homogeneity by a five-step procedure involving solubilization in CHAPS and sequential chromatographies on Sephacryl S-400, DEAE-Trisacryl, Zn(2+)-chelating Sepharose and Superose 12 columns. The purified protein has a molecular mass of 68 +/- 2 kDa, as determined by SDS/PAGE and gel filtration, suggesting that the enzyme behaves as a monomer. The concentration-dependence of MAGL activity with monooleoylglycerol, the preferred substrate showed kinetics typical of an interfacial lipolytic enzyme displaying optimal activity on emulsified substrate particles; apparent Km values were 0.27 mM and 0.49 mM for the sn-1(3)- and sn-2-isomers respectively. MAGL had no, or negligible, activity towards tri-oleoylglycerol, di-oleoylglycerol, oleoylcholesterol, oleoyl-CoA and phosphatidylcholine; it was inhibited by di-isopropylfluorophosphate, PMSF and diethyl p-nitrophenyl phosphate, suggesting that MAGL is a serine hydrolase. MAGL activity was not modified by bile salt or apolipoprotein C-II, whereas a dose-dependent inhibition was observed with apolipoprotein A-I.

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Purification and properties of α-mannosidase II from Golgi-like membranes of baculovirus-infected Spodoptera frugiperda (IPLB-SF-21AE) cells

Biochemical Journal ◽

10.1042/bj3240951 ◽

1997 ◽

Vol 324 (3) ◽

pp. 951-956 ◽

Cited By ~ 20

Author(s):

Jianxin REN ◽

Francis J. CASTELLINO ◽

Roger K. BRETTHAUER

Keyword(s):

Spodoptera Frugiperda ◽

Reaction Pathway ◽

Gel Filtration ◽

Deae Cellulose ◽

Enzymic Activity ◽

Mannose Residue ◽

Lepidopteran Insect ◽

Reducing Conditions ◽

Apparent Homogeneity ◽

Purification And Properties

An α-mannosidase II-like activity was identified in baculovirus-infected Spodoptera frugiperda (IPLB-SF21-AE) cells. The enzyme responsible was purified from Golgi-type membranes to apparent homogeneity by using a combination of steps including DEAE-cellulose, hydroxyapatite, concanavalin A–Sepharose and gel filtration chromatography. The molecular mass of this purified protein was approx. 120 kDa by SDS/PAGE under reducing conditions and approx. 240 kDa under non-reducing conditions, indicating that the enzyme is a disulphide-linked dimer. Substrates demonstrated to undergo hydrolysis with this enzyme were GlcNAc-Man5-GlcNAc-GlcNAc (non-reduced and reduced) and p-nitrophenyl α-d-mannopyranoside. The oligosaccharide substrate was converted into GlcNAc-Man3-GlcNAc-GlcNAc through an intermediate GlcNAc-Man4-GlcNAc-GlcNAc. Treatment of the isolated intermediate oligosaccharide with endoglycosidase H resulted in its conversion into GlcNAc-Man4-GlcNAc. This indicated that it contained the α-1,3-linked mannose residue on the α-1,6-linked mannose arm and showed that the α-1,6-linked mannose residue on the α-1,6-linked mannose arm had been preferentially hydrolysed by the mannosidase. The oligosaccharide lacking the β-1,2-linked GlcNAc residue on the α-1,3-linked mannose arm (Man5-GlcNAc-GlcNAc) was not hydrolysed in the presence of the enzyme. Metal ions were not required for enzymic activity on any of the substrates, but Cu2+ was strongly inhibitory. The activity of the enzyme was inhibited at low concentrations of swainsonine, but much higher concentrations of 1-deoxymannojirimycin were required to achieve inhibition. All of these properties are characteristic of mannosidase II enzymes from other eukaryotic tissues. The presence of mannosidase II in lepidopteran insect cells would allow entry of N-linked glycoproteins into the complex processing reaction pathway or into the terminal Man3-GlcNAc-GlcNAc pathway.

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Purification and properties of glutathione peroxidase from human placenta

Biochemical Journal ◽

10.1042/bj1770471 ◽

1979 ◽

Vol 177 (2) ◽

pp. 471-476 ◽

Cited By ~ 43

Author(s):

Y C Awasthi ◽

D D Dao ◽

A K Lal ◽

S K Srivastava

Keyword(s):

Molecular Weight ◽

Glutathione Peroxidase ◽

Human Placenta ◽

Gel Filtration ◽

Cumene Hydroperoxide ◽

Exchange Chromatography ◽

Human Erythrocytes ◽

Kinetic Properties ◽

Peroxidase Isoenzyme ◽

Purification And Properties

Glutathione peroxidase (glutathione–H2O2 oxidoreductase; EC 1.11.1.9) was purified to homogeneity from human placenta by using (NH4)2SO4 precipitation, ion-exchange chromatography, Sephadex gel filtration and preparative polyacrylamide-disc-gel electrophoresis. Glutathione peroxidase from human placenta is a tetramer, having 4g-atoms of selenium/mol of protein. The molecular weight of the enzyme is about 85000 with a subunit size of about 22,000. Kinetic properties of the enzyme are described. On incubation with cyanide, glutathione peroxidase is completely and irreversibly inactivated and selenium is released as a low-molecular-weight fragment. Reduced glutathione, beta-mercaptoethanol and dithiothreitol protect the enzyme from inactivation by cyanide and the release of selenium. Properties of human placental glutathione peroxidase are similar to those of isoenzyme A reported earlier by us from human erythrocytes. The presence of isoenzyme, B, reported earlier by us in human erythrocytes, was not detected in placenta. Also selenium-independent glutathione peroxidase (isoenzyme II), which is specific for cumene hydroperoxide, was not present in human placenta.

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Purification and Properties of a Neutral Protease from Soil Bacterium WM 122

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649266 ◽

1977 ◽

Vol 37 (03) ◽

pp. 556-565 ◽

Cited By ~ 1

Author(s):

S. E Papaioannou ◽

W. J Marsheck

Keyword(s):

Methyl Ester ◽

Specific Activity ◽

Polyacrylamide Gel Electrophoresis ◽

Gel Filtration ◽

High Specific Activity ◽

Soil Bacterium ◽

Ester Hydrochloride ◽

Apparent Homogeneity ◽

Purification And Properties ◽

Hydrolysis Of

SummaryAn extracellular protease SN 687, secreted by the soil bacterium isolate WM 122, has been purified by means of gel filtration, ammonium sulfate precipitation, DEAE-Sephadex and hydroxylapatite chromatography. Apparent homogeneity was ascertained by Polyacrylamide gel electrophoresis. The protease was inactivated by ethylenediamine tetracetic acid (EDTA) but not by diisopropylfluorophosphate (DFP), and it was partially inhibited by serum inhibitors. SN 687 was shown to be of high specific activity against casein and fibrin, but it did not hydrolyze L- lysine -methyl ester dihydrochloride (LME), p-tosyl-L-arginine-methyl ester hydrochloride (TAME) and N-benzoyl-L-tyrosine-ethyl ester hydrochloride (BTEE) synthetic substrates. The optimum pH for hydrolysis of casein was 7.5 and the molecular weight, as determined by gel filtration, was 31,000.

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Purification and properties of methionyl-transfer-ribonucleic acid synthetase from Escherichia coli

Biochemical Journal ◽

10.1042/bj1050017 ◽

1967 ◽

Vol 105 (1) ◽

pp. 17-24 ◽

Cited By ~ 45

Author(s):

R. L. Heinrikson ◽

B S Hartley

Keyword(s):

Escherichia Coli ◽

Polyacrylamide Gel Electrophoresis ◽

Gel Filtration ◽

Distinct Species ◽

Active Species ◽

E Coli ◽

Apparent Homogeneity ◽

Purification And Properties ◽

Ribonuclease I ◽

Free Strain

1. Methionyl-t-RNA synthetase (where t-RNA denotes ‘soluble’ or transfer RNA) has been purified to apparent homogeneity from a ribonuclease I-free strain of Escherichia coli. Polyacrylamide-gel electrophoresis of the final product revealed a single band. The purified enzyme catalyses the exchange of 450μmoles of pyrophosphate into ATP/mg. in 15min. at 37°. 2. Methionyl-t-RNA synthetase is specific for the l-isomer of methionine, but appears to catalyse the methionylation of two distinct species of t-RNA, both of which are specific for methionine, but only one of which may be subsequently formylated. 3. The Michaelis constant for l-methionine is 2×10−4m in the ATP–PPi exchange assay and 2×10−5m for the acylation of t-RNA. 4. Gel filtration of both crude and highly purified preparations of methionyl-t-RNA synthetase on Sephadex G-200 indicates that the active species of enzyme has a molecular weight of about 190000. The amino acid composition of the enzyme is similar to those reported for the isoleucine and tyrosine enzymes from E. coli.

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Purification and initial characterization of proline 4-hydroxylase from Streptomyces griseoviridus P8648: a 2-oxoacid, ferrous-dependent dioxygenase involved in etamycin biosynthesis

Biochemical Journal ◽

10.1042/bj3130185 ◽

1996 ◽

Vol 313 (1) ◽

pp. 185-191 ◽

Cited By ~ 62

Author(s):

Christopher C. LAWRENCE ◽

Wendy J. SOBEY ◽

Robert A. FIELD ◽

Jack E. BALDWIN ◽

Christopher J. SCHOFIELD

Keyword(s):

Active Site ◽

Gel Filtration ◽

Ferrous Ion ◽

Typical Member ◽

Apparent Homogeneity ◽

Initial Characterization ◽

Dependent Inhibition ◽

Proline Hydroxylation ◽

Time Dependent Inhibition

Proline 4-hydroxylase is a 2-oxoacid, ferrous-ion-dependent dioxygenase involved in the biosynthesis of the secondary metabolite etamycin. The purification, in low yield, of proline 4-hydroxylase from Streptomyces griseoviridus P8648 to near apparent homogeneity and its initial characterization are reported. In most respects proline 4-hydroxylase is a typical member of the 2-oxoacid-dependent dioxygenase family. It is monomeric (Mr approx. 38000) (by gel filtration on Superdex-G75) and has typically strict requirements for ferrous ion and 2-oxoglutarate. The enzyme was inhibited by aromatic analogues of 2-oxoglutarate. L-Proline-uncoupled turnover of 2-oxoglutarate to succinate and CO2 was observed. The addition of L-ascorbate did not stimulate L-proline-coupled turnover of 2-oxoglutarate, but did stimulate L-proline-uncoupled turnover. L-Ascorbate caused a time-dependent inhibition of L-proline hydroxylation. The enzyme was completely inactivated by preincubation with diethyl pyrocarbonate under histidine-modifying conditions. This inactivation could be partially prevented by the inclusion of L-proline and 2-oxoglutarate in the preincubation mixture, suggesting the presence of histidine residue(s) at the active site.

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Microbial metabolism of amino alcohols. Purification and properties of coenzyme B12-dependent ethanolamine ammonia-lysae of Escherichia coli

Biochemical Journal ◽

10.1042/bj1750555 ◽

1978 ◽

Vol 175 (2) ◽

pp. 555-563 ◽

Cited By ~ 14

Author(s):

Carol M. Blackwell ◽

John M. Turner

Keyword(s):

Escherichia Coli ◽

Enzyme Activity ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Gel Filtration ◽

Coenzyme B12 ◽

Apparent Homogeneity ◽

Purification And Properties ◽

Protein Components ◽

Inhibited Enzyme

1. The 120-fold purification of ethanolamine ammonia-lyase from Escherichia coli extracts, to apparent homogeneity, is described. Ethanolamine, dithiothreitol, glycerol and KCl protected the apoenzyme from inactivation. 2. At the optimum pH7.5, Km values for ethanolamine and coenzyme B12 were 44μm and 0.42μm respectively. The Km for ethanolamine was markedly affected by pH, transitions occurring at pH7.0 and 8.35. 3. The enzyme was specific for ethanolamine as substrate, none of the 18 analogues tested being active. l-2-Aminopropan-l-ol (Ki 0.86μm), dl-1-aminopropan-2-ol (Ki 2.2μm) and dl-1,3-diaminopropan-2-ol (Ki 88.0μm) inhibited competitively. 4. Enzyme activity was inhibited, irreversibly and non-competitively, by the coenzyme analogues methylcobalamin (Ki 1.4nm), hydroxocobalamin (Ki 2.1nm) and cyanocobalamin (Ki 4.8nm). 5. Iodoacetamide inhibited in the absence of ethanolamine, but only slightly in its presence. p-Hydroxymercuribenzoate inhibited markedly even in the presence of ethanolamine. Dithiothreitol and 2-mercaptoethanol (less effectively) restored activity to the enzyme dialysed against buffer containing ethanolamine. 6. Although K+ ions stabilized the enzyme during dialysis or storage, they were not necessary for activity. 7. Gel filtration showed the enzyme to be of high molecular weight, ultracentrifugal studies giving s20,w of 16.4 and an estimated mol.wt. 560400. The isoelectric point for the apoenzyme was approx. pH5.0. inhibited enzyme activity at concentrations above 1m (95% inhibition at 3m) and sodium dodecyl sulphate/polyacrylamide-gel electrophoresis indicated protein subunits of mol.wt. 61400. 8. Immunological studies showed that the E.coli enzyme was closely related to those of other enterobacteria, but only distantly to that of Clostridium sp. A double precipitin band suggested that the apoenzyme may be made up of two protein components.

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Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

Thrombosis and Haemostasis ◽

10.1055/s-0038-1657167 ◽

1982 ◽

Vol 47 (03) ◽

pp. 197-202 ◽

Cited By ~ 23

Author(s):

Kurt Huber ◽

Johannes Kirchheimer ◽

Bernd R Binder

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Human Urine ◽

Gel Filtration ◽

Chain Structure ◽

The Other ◽

Single Chain ◽

Apparent Homogeneity ◽

Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

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