scholarly journals Partial purification and properties of a transamidinase from Lathyrus sativus seedlings. Involvement in homoarginine metabolism and amine interconversions

1980 ◽  
Vol 189 (3) ◽  
pp. 553-560 ◽  
Author(s):  
K S Srivenugopal ◽  
P R Adiga
Keyword(s):  
Specific Activity ◽  
Hydrolytic Activity ◽  
Lathyrus Sativus ◽  
Partial Purification ◽  
Natural Occurrence ◽  
Thiol Compounds ◽  
Reaction Conversion ◽  
Purification And Properties ◽  
Plant Embryo

A transamidinase was purified 463-fold from Lathyrus sativus seedlings by affinity chromatography on homoarginine–Sepharose. The enzyme exhibited a wide substrate specificity, and catalysed the reversible transfer of the amidino groups from donors such as arginine, homoarginine and canavanine to acceptors such as lysine, putrescine, agmatine, cadaverine and hydroxylamine. The enzyme could not be detected in the seeds, and attained the highest specific activity in the embryo axis on day 10 after seed germination. Its thiol nature was established by strong inhibition by several thiol blockers and thiol compounds in the presence of ferricyanide. In the absence of an exogenous acceptor, it exhibited weak hydrolytic activity towards arginine. It had apparent mol.wt. 210000, and exhibited Michaelis–Menten kinetics with Km 3.0 mM for arginine. Ornithine competitively inhibited the enzyme, with Ki 1.0 mM in the arginine–hydroxylamine amidino-transfer reaction. Conversion experiments with labelled compounds suggest that the enzyme is involved in homoarginine catabolism during the development of plant embryo to give rise to important amino acids and amine metabolites. Presumptive evidence is also provided for its involvement in the biosynthesis of the guanidino amino acid during seed development. The natural occurrence of arcain in L. sativus and mediation of its synthesis in vitro from agmatine by the transamidinase are demonstrated.

scholarly journals Quantification and characterization of the 5’exonuclease activity of the lysosomal nuclease PLD3 by a novel cell-based assay

2020 ◽  
pp. jbc.RA120.015867
Author(s):  
Cedric Cappel ◽  
Adriana Carolina Gonzalez ◽  
Markus Damme
Keyword(s):  
Lupus Erythematosus ◽  
Specific Activity ◽  
Nuclease Activity ◽  
Hydrolytic Activity ◽  
Proteolytic Processing ◽  
Exonuclease Activity ◽  
Fluorescence Quencher

Phospholipase D3 (PLD3) and phospholipase D4 (PLD4), the most recently described lysosomal nucleases, are associated with Alzheimer`s disease, spinocerebellar ataxia, and systemic lupus erythematosus. They exhibit 5’ exonuclease activity on single-stranded DNA, hydrolyzing it at the acidic pH associated with the lysosome. However, their full cellular function is inadequately understood. To examine these enzymes, we developed a robust and automatable cell-based assay based on fluorophore- and fluorescence-quencher coupled oligonucleotides for the quantitative determination of acidic 5’ exonuclease activity. We validated the assay under knockout and PLD-overexpression conditions, and then applied it to characterize PLD3 and PLD4 biochemically. Our experiments revealed PLD3 as the principal acid 5’ exonuclease in HeLa cells, where it showed a markedly higher specific activity compared to PLD4. We further used our newly developed assay to determine the substrate specificity and inhibitory profile of PLD3, and found that proteolytic processing of PLD3 is dispensable for its hydrolytic activity. We followed the expression, proteolytic processing, and intracellular distribution of genetic PLD3 variants previously associated with Alzheimer’s disease and investigated each variant's effect on the 5’ nuclease activity of PLD3, finding that some variants lead to reduced activity, but others not. The development of a PLD3/4-specific biochemical assay will be instrumental in understanding better both nucleases and their incompletely unknown roles in vitro and in vivo.

scholarly journals Solubilization, partial purification and properties of N-methylglutamate dehydrogenase from Pseudomonas aminovorans

1977 ◽  
Vol 161 (2) ◽  
pp. 357-370 ◽  
Author(s):  
C W Bamforth ◽  
P J Large
Keyword(s):  
Cytochrome C ◽  
Electron Acceptor ◽  
Specific Activity ◽  
Partial Purification ◽  
Ph Optimum ◽  
Transport Chain ◽  
Purification And Properties ◽  
Solubilized Enzyme ◽  
Triton X ◽  
Sepharose 4B

1. Extracts of amine-grown Pseudomonas aminovorans contained a particle-bound N-methylglutamate dehydrogenase (EC 1.5.99.5). The enzyme was not present in succinate-grown cells, and activity appeared before growth began in succinate-grown cells which had been transferred to methylamine growth medium. 2. Membrane-containing preparations from methylamine-grown cells catalysed an N-methylglutamate-dependent uptake of O2 or reduction of cytochrome c, which was sensitive to inhibitors of the electron-transport chain. 3. N-Methylglutamate dehydrogenase activity with phenazine methosulphate or 2,6-dichlorophenol-indophenol as electron acceptor could be solubilized with 1% (w/v) Triton X-100. The solubilized enzyme was much less active with cytochrome c as electron acceptor and did not sediment in 1 h at 150000g. Solubilization was accompanied by a change in the pH optimum for activity. 4. The solubilized enzyme was partially purified by Sepharose 4B and hydroxyapatite chromatograpy to yield a preparation 22-fold increased in specific activity over the crude extract. 5. The partially-purified enzyme was active with sarcosine, N-methylalanine and N-methylaspartate as well as with N-methylglutamate. Evidence suggesting activity with N-methyl D-amino acids as well as with the L-forms was obtained. 6. The enzyme was inhibited by p-chloromercuribenzoate, iodoacetamide and by both ionic and non-ionic detergents. 2-Oxoglutarate and formaldehyde were also inhibitors. 7. Kinetic analysis confirmed previous workers' observations of a group transfer (Ping Pong) mechanism. 8. Spectral observations suggested that the partially purified preparation contained flavoprotein and a b-type cytochrome. 9. The role of the enzyme in the oxidation of methylamine is discussed.

Partial purification of a hypertensive substance from rat erythrocytes

1985 ◽  
Vol 63 (10) ◽  
pp. 1321-1326 ◽  
Author(s):  
William D. McCumbee ◽  
Gary L. Wright
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Calcium Uptake ◽  
Specific Activity ◽  
Present Report ◽  
Fold Increase ◽  
Partial Purification ◽  
Rat Erythrocytes ◽  
In Vitro Effects

A crude extract prepared from rat erythrocytes was previously shown to contain an active component (hypertensive factor, HF) that stimulates the in vitro uptake of calcium by aortic rings and causes a sustained and severe elevation in systolic blood pressure in normotensive rats. The present report demonstrates that the in vitro effects of HF on calcium uptake are concentration dependent and reversible, and that these effects on calcium uptake provide a convenient bioassay for monitoring the purification of HF. HF was prepared from a diffusate obtained by dialyzing hemolyzed rat erythrocytes. The diffusate was applied successively to molecular sieve and anion exchange columns resulting in a 1500-fold increase in specific activity relative to the starting hemolysate. The compound stimulating calcium uptake was found to be heat stable and resistant to digestion with trypsin and chymotrypsin. In contrast, treatment with pronase E, a nonspecific protease, markedly increased the calcium transport stimulatory activity. The administration of the purified preparation to normotensive rats having a systolic blood pressure of 118 ± 2 Torr (1 Torr = 133.322 Pa) resulted in a significant elevation of blood pressure (171 ± 11 Torr) by day 5. The severity of this increase further suggests that there is a marked enhancement in potency relative to earlier fractions that were examined. Perhaps most importantly, these results indicate that, at this stage of purification, the pressor component and the calcium-stimulatory component of HF appear to co-purify.

scholarly journals Partial Purification of Alkaline Protease as Thrombolytic Agent from Mutant Strain Bacillus licheniformis EMS250-O-1

2017 ◽  
Vol 15 (2) ◽  
pp. 135-141 ◽  
Author(s):  
Md Asad Uz Zaman ◽  
Md Arafat Al Mamun ◽  
Shakila Nargis Khan ◽  
Md Mozammel Hoq ◽  
Md Abdul Mazid
Keyword(s):  
Mutant Strain ◽  
Bacillus Licheniformis ◽  
Specific Activity ◽  
Cardiovascular Complications ◽  
Clot Lysis ◽  
Partial Purification ◽  
Thrombolytic Activity ◽  
Ammonium Sulphate Precipitation ◽  
Maximum Stability

Thrombosis leads to myocardial infarction, stroke and other cardiovascular complications. Microbial thrombolytic agents such as urokinase, streptokinase etc. are used to treat complications related to thrombosis. To search for new microbial enzymes as thrombolytics having better efficacy and specificity, Bacillus licheniformis EMS-O-1 mutant strain was cultured in modified urea-molasses media followed by purification using ammonium sulphate precipitation and ultrafiltration through centricon tube of 100 MWCO value. The yield of crude enzyme was 11129.14 U/mg and after purification 40180.46 U/mg. Purification process increased the specific activity of purified enzyme to 12.28 fold with a recovery of 17.79%. The purified enzyme was a serine protease with molecular weight of 25.5 kDa as confirmed by irreversible inhibition of activity with phenylmethylsulfonyl fluoride (PMSF) followed by SDS-PAGE gel image and by LC-MS analyses. In vitro clot lysis assay of the purified enzyme exhibited 38.30% thrombolytic activity. The crude enzymes from the mutant strain EMS-O-1 were found to be stable up to 50oC and showed maximum stability between pH range 7.5 to 8.5. These findings signify that proteases produced by B. licheniformis mutant have the potential to be developed as a viable thrombolytic agent.Dhaka Univ. J. Pharm. Sci. 15(2): 135-141, 2016 (December)

scholarly journals Partial purification and properties of l-asparagine synthetase from mouse pancreas

1979 ◽  
Vol 181 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Harry A. Milman ◽  
David A. Cooney
Keyword(s):  
Specific Activity ◽  
Asparagine Synthetase ◽  
Partial Purification ◽  
Synthetase Activity ◽  
Mouse Pancreas ◽  
Purification And Properties ◽  
Bean Trypsin Inhibitor ◽  
Thiol Reagent ◽  
High Concentrations ◽  
Glutaminase Activity

l-Asparagine synthetase was partially purified from mouse pancreas to a final mean specific activity of 0.10 unit/mg of protein. The enzyme exhibited an l-glutaminase activity which was not affected by l-asparate, NH4Cl, ATP–MgCl2, l-glutamate, AMP (sodium salt) or sodium pyrophosphate. The l-glutamine-dependent l-asparagine synthetase activity of the partially purified enzyme from mouse pancreas was markedly decreased by freezing for 7 days at −87°C in the presence of 1mm-dithiothreitol, but effectively protected from inactivation by high concentrations (10mm) of the thiol reagent. The l-glutaminase activity of the enzyme was inhibited by antagonists of l-glutamine (e.g. 6-diazo-5-oxo-l-norleucine, 5-chloro-4-oxo-l-norvaline, 5-diazo-4-oxo-l-norvaline and NSC-163501) and thiol-reactive compounds (e.g. 2-amino-4-arsenophenol hydrochloride, maleimide, mucochloric acid and ZnCl2), but not by aminomalonic acid, the next lower homologue of l-aspartate, nor by l-homoserine β-adenylate, an analogue of the presumed transitory covalent intermediate. The complete forward reaction catalysed by l-asparagine synthetase from mouse pancreas appears to be irreversible and essentially stoicheiometric under the conditions examined. Mouse pancreas contains a proteolytic inhibitor of l-asparagine synthetase separable from the enzyme by ion-exchange column chromatography. The inhibitor is activated by incubation at 4°C for 110h and inactivated by soya-bean trypsin inhibitor, di-isopropyl phosphorofluoridate and boiling.

scholarly journals Purification and properties of adenosine triphosphate–creatine phosphotransferase from muscle of the dogfish Scylliorhinus canicula

1972 ◽  
Vol 128 (5) ◽  
pp. 1241-1253 ◽  
Author(s):  
B. Simonarson ◽  
D. C. Watts
Keyword(s):  
Creatine Kinase ◽  
Specific Activity ◽  
Thiol Group ◽  
Effect Of Temperature ◽  
Thiol Groups ◽  
High Concentration ◽  
Nitrobenzoic Acid ◽  
Purification And Properties ◽  
Michaelis Constants

1. Creatine kinase occurs in high concentration in the soluble proteins of dogfish muscle. A fourfold purification gives essentially pure enzyme but with a low specific activity. This appears to be a property of the native enzyme and not a result of the isolation procedures used. 2. The amino acid composition is similar to that of other phosphagen kinases, but the enzyme differs from mammalian creatine kinases in having four thiol groups readily reactive towards 5,5′-dithiobis-(2-nitrobenzoic acid). Titration of two thiol groups is accompanied by almost complete loss of activity. The remaining two thiol groups react at different rates, suggesting that modifying the third thiol group affects the reactivity of the fourth thiol group. 3. The enzyme is markedly protected against inactivation by iodoacetamide by MgATP or MgADP. Addition of creatine to MgADP decreases protection, but the further addition of Cl− restores protection to the original value. The quaternary MgADP–creatine–enzyme–nitrate complex protects very strongly as is found for the rabbit enzyme. The involvement of the conformational state of the enzyme in such effects is discussed. 4. Creatine kinase from both dogfish and rabbit is equally sensitive to urea denaturation. Urea protects the dogfish enzyme by about 9% against inhibition by iodoacetamide. 5. The formation of a hybrid between the dogfish and rabbit enzymes in vitro has been demonstrated. 6. At high substrate concentrations the dogfish enzyme shows apparent ordered kinetics. The effect of temperature on Vmax. and the Michaelis constants for MgATP and creatine were determined. These and changes in the apparent activation energy suggest that limited adaptation has occurred commensurate with physiological need.

scholarly journals Purification and properties of the adenosine triphosphatase released from the liver mitochondrial membrane by chloroform

1979 ◽  
Vol 178 (2) ◽  
pp. 289-297 ◽  
Author(s):  
D. D. Tyler ◽  
Pauline R. Webb
Keyword(s):  
Extraction Method ◽  
Adenosine Triphosphatase ◽  
Specific Activity ◽  
Hydrolytic Activity ◽  
Chloroform Extract ◽  
Soluble Enzyme ◽  
Submitochondrial Particles ◽  
Reactive Material ◽  
Bicarbonate Ions ◽  
Purification And Properties

1. Soluble ATPase (adenosine triphosphatase) activity is released when rat liver submitochondrial particles are shaken with chloroform, provided that ATP or glycerol is present in the suspending medium. The extraction is very rapid and appears to be complete. 2. The ATPase of the chloroform extract is about 50% pure and can be readily purified to a specific activity of 60–70μmol/min per mg of protein by (NH4)2SO4 fractionation and column chromatography on Sephadex G-200. 3. The particulate and soluble ATPases have many similar properties, including their Km values for ATP, activation by various metal ions, hydrolytic activity with other nucleotides and stimulation by bicarbonate ions. 4. Unlike the particulate enzyme, the soluble enzyme is cold-labile and insensitive to oligomycin. 5. The molecular weight indicated by the mobility of the soluble ATPase on Sepharose 6B is 360000. 6. The soluble ATPase combines very readily with liver submitochondrial particles depleted of ATPase by salt extraction, and oligomycin-sensitivity is restored. Very little recombination of the enzyme occurs with chloroform-extracted particles. 7. The soluble enzyme contains orcinol-reactive material, suggesting that it may be a glycoprotein. The carbohydrate content was estimated to be 1–2% by weight. 8. It is concluded that the liver ATPase obtained by the chloroform extraction method of Beechey, Hubbard, Linnett, Mitchell & Munn [(1975) Biochem. J.148, 533–537] is similar to other preparations described previously and that this method is superior in simplicity and speed.

scholarly journals Characterization and partial purification of a haemopoietic cell growth factor in WEHI-3 cell conditioned medium

1983 ◽  
Vol 210 (3) ◽  
pp. 747-759 ◽  
Author(s):  
G W Bazill ◽  
M Haynes ◽  
J Garland ◽  
T M Dexter
Keyword(s):  
Growth Factor ◽  
Progenitor Cells ◽  
Specific Activity ◽  
Sodium Dodecyl ◽  
Cell Types ◽  
Partial Purification ◽  
Erythroid Progenitor ◽  
Leukaemia Cell Line ◽  
P Cells

A myelomonocytic leukaemia cell line, WEHI-3, releases into its growth medium factors which stimulate the development of pluripotential cells, granulocyte/macrophage progenitor cells, megakaryocytic and erythroid progenitor cells. Also present is a factor which is essential for the continued proliferation in vitro of a variety of haemopoietic precursor cell lines of a granulocytic nature (FDC-P cells). Characterization of this growth factor has demonstrated that it is a glycoprotein of apparent Mr 25 800, in which the carbohydrate component appears to be important for activity. After several purification steps, there is an increase in specific activity of approx. 4000-fold over the starting material. At each stage of purification, the factor necessary for the proliferation of FDC-P cells ‘co-purifies’ with activity which stimulates the proliferation and development of normal multipotential haemopoietic cells as well as megakaryocytic, erythroid and granulocytic committed progenitor cells. This ‘co-purification’ occurs to the extent that the multilineage stimulating factor and the FDC-P growth factor can be eluted from the same region of sodium dodecyl sulphate/polyacrylamide gels. Thus, evidence so far, using different starting methods and purification regimes, suggests that one molecule may have multiple activities on diverse cell types.

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