scholarly journals Enzymes catalysing conjugations of glutathione with αβ-unsaturated carbonyl compounds

1968 ◽  
Vol 109 (4) ◽  
pp. 651-661 ◽  
Author(s):  
E. Boyland ◽  
L. F. Chasseaud
Keyword(s):  
Ammonium Sulphate ◽  
Carbonyl Compounds ◽  
Lower Energy ◽  
Rat Kidney ◽  
Heat Inactivation ◽  
Phenoxyacetic Acid ◽  
Diethyl Maleate ◽  
Catalysed Reaction ◽  
Ammonium Sulphate Fractionation ◽  
Inhibition Studies

1. Heat-inactivation experiments, ammonium sulphate-fractionation studies, enzyme-inhibition studies with S-(αβ-diethoxycarbonylethyl)glutathione, and evidence from the distribution of activities in rat liver, in rat kidney and in the livers of other animals, indicate that reactions of glutathione with (i) trans-benzylideneacetone, (ii) cyclohex-2-en-1-one, (iii) trans-cinnamaldehyde, (iv) diethyl maleate, (v) diethyl fumarate and (vi) 2,3-dimethyl-4-(2-methylenebutyryl)phenoxyacetic acid are catalysed by different enzymes. 2. Evidence is presented that the enzymes catalysing the reactions of glutathione with substrates (i)–(iv) are different from glutathione S-alkyltransferase, S-aryltransferase and S-epoxidetransferase. 3. The name ‘glutathione S-alkenetransferases’ is proposed for enzymes catalysing reactions of glutathione with αβ-unsaturated compounds. 4. The Arrenhius plot for the enzyme-catalysed reaction of diethyl maleate with glutathione is discontinuous, with lower energy of activation at 38°.

scholarly journals Glutathione S-aralkyltransferase

1969 ◽  
Vol 115 (5) ◽  
pp. 985-991 ◽  
Author(s):  
E. Boyland ◽  
L. F. Chasseaud
Keyword(s):  
Ammonium Sulphate ◽  
Rat Liver ◽  
Benzyl Chloride ◽  
Animal Species ◽  
Rat Kidney ◽  
Acid Precipitation ◽  
Heat Inactivation ◽  
Catalysed Reaction ◽  
Glutathione S Transferases ◽  
Ammonium Sulphate Fractionation

1. The name ‘glutathione S-aralkyltransferase’ is proposed for the enzyme catalysing the reaction of benzyl chloride with GSH. 2. Results from heat-inactivation studies, ammonium sulphate-fractionation and acid-precipitation experiments, and studies of the distribution of activities in rat liver, in rat kidney and in the livers of other animals indicate that glutathione S-aralkyltransferase differs from glutathione S-alkyltransferase, S-aryltransferase, S-epoxidetransferase and an S-alkenetransferase. 3. The distribution of these enzymes in the livers of the animal species examined was different. 4. Glutathione S-alkyltransferase, S-aralkyltransferase and the S-alkenetransferase that are present in rat liver supernatant were inhibited by GSSG, and the nature of the inhibition varied in each case. 5. 3,5-Di-tert.-butyl-4-hydroxybenzyl acetate reacts spontaneously with GSH, but the rat liver-supernatant-catalysed reaction of GSH with this and other aralkyl esters was weak. 6. A probable function of the glutathione S-transferases is the protection of cellular constituents from strong electrophilic agents.

scholarly journals Distribution of enzymes that catalyse reactions of glutathione with αβ-unsaturated compounds

1973 ◽  
Vol 131 (4) ◽  
pp. 765-769 ◽  
Author(s):  
L. F. Chasseaud
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Rat Kidney ◽  
Acid Precipitation ◽  
Heat Inactivation ◽  
Phenoxyacetic Acid ◽  
Mercapturic Acids ◽  
Vertebrate Species ◽  
Methyl Vinyl

1. A study of the distribution of glutathione S-alkenetransferases in the livers of vertebrate species suggests that different enzymes may catalyse reactions of GSH with (i) trans-benzylideneacetone, (ii) 2,3-dimethyl-4(2-methylenebutyryl)phenoxyacetic acid, (iii) cinnamonitrile, (iv) o-chlorobenzylidenemalononitrile, (v) methyl vinyl sulphone, and (vi) 3-(β-nitrovinyl)indole. 2. Glutathione S-alkenetransferase activity was generally greatest in rat liver, but the enzyme in hamster liver was more active towards o-chlorobenzylidenemalononitrile, and the enzyme in rabbit, hamster, guinea-pig and mouse livers was more active towards methyl vinyl sulphone. 3. Results from studies of the distribution of activities in rat liver and rat kidney, heat inactivation of rat liver supernatants, and (NH4)2SO4 fractionation and acid-precipitation experiments, differentiated further between some of the enzymes concerned with substrates (i)–(vi). 4. The infrequent detection of mercapturic acids in vivo is discussed.

Bovine milk esterases

1971 ◽  
Vol 38 (2) ◽  
pp. 171-177 ◽  
Author(s):  
B. J. Kitchen
Keyword(s):  
Ammonium Sulphate ◽  
Bovine Milk ◽  
Skim Milk ◽  
Histochemical Staining ◽  
Major Type ◽  
Polyacrylamide Gels ◽  
Selective Inhibitors ◽  
Choline Ester ◽  
Ultra Filtration ◽  
Ammonium Sulphate Fractionation

SummaryThe type and distribution of esterases in milk has been investigated using selective inhibitors during normal assay procedures and during histochemical staining of polyacrylamide gels. Enzyme solutions were obtained from skim-milk by acid and alkali precipitation, followed by ammonium sulphate fractionation, ultra-filtration and Sephadex G-100 chromatography. The major type of esterase present was an aryl-esterase (E.C. 5.1.1.2) while a smaller amount of a choline-ester hydrolase (E.C. 3.1.1.7; 3.1.1.8) was detected. The significance of these findings is discussed.

GLYCYL-RNA SYNTHETASE OF RAT LIVER: PARTIAL PURIFICATION AND EFFECTS OF SOME METAL IONS ON ITS ACTIVITY

1963 ◽  
Vol 41 (1) ◽  
pp. 1123-1133 ◽  
Author(s):  
M. J. Fraser
Keyword(s):  
Heat Treatment ◽  
Metal Ions ◽  
Ammonium Sulphate ◽  
Rat Liver ◽  
Partial Purification ◽  
Ammonium Sulphate Fractionation ◽  
Stimulation Of

Glycyl-RNA synthetase has been purified 40-fold from a 105,000 × g supernatant of an homogenate of rat liver by successive precipitation at pH = 5.0, heat treatment at 55 °C for 3.0 minutes in the presence of 1.0 mM ATP, and ammonium sulphate fractionation. The purified fractions catalyzed glycine-dependent ATP-32PP exchange. The effect of some metal ions on glycine activation was studied. Activation occurred in the presence of either Mg++or Mn++. The apparent stimulation of glycine activation by Co++was found to be an artifact.

THE ENZYMATIC SYNTHESIS OF CITRIC ACID BY CELL-FREE EXTRACTS OF ASPERGILLUS NIGER

1954 ◽  
Vol 32 (4) ◽  
pp. 434-439 ◽  
Author(s):  
C. V. Ramakrishnan ◽  
S. M. Martin
Keyword(s):  
Citric Acid ◽  
Calcium Phosphate ◽  
Aspergillus Niger ◽  
Ammonium Sulphate ◽  
Enzymatic Synthesis ◽  
Coenzyme A ◽  
Acetyl Coenzyme A ◽  
Acetyl Coenzyme ◽  
Ammonium Sulphate Fractionation ◽  
Condensing Enzyme

Cell-free extracts of Aspergillus niger, N.R.C. 233, have been shown to contain the enzymes necessary to catalyze the synthesis of citrate from ATP, acetate, and oxalacetate. The "condensing enzyme", which catalyzes the condensation of acetyl-coenzyme A and oxalacetate to yield citrate, has been isolated and purified approximately 50-fold by a combination of steps involving ammonium sulphate fractionation and calcium phosphate gel adsorption.

scholarly journals Studies on Ovalbumin V. The Amino Acid Composition and Some Properties of Chicken, Duck, and Turkey Ovalbumins

1970 ◽  
Vol 23 (5) ◽  
pp. 1221 ◽  
Author(s):  
MB SmIth ◽  
Joan F Back
Keyword(s):  
Amino Acid ◽  
Amino Acid Composition ◽  
Ammonium Sulphate ◽  
Acid Composition ◽  
Isoelectric Focusing ◽  
Ph Gradient ◽  
Ammonium Sulphate Fractionation

The ovalbumins from chicken, duck, and turkey eggs were prepared by ammonium sulphate fractionation and purified by isoelectric focusing in a pH gradient from 3 to 6. Amino acid analyses show a closer relationship between turkey and chicken ovalbumins than between duck and chicken ovalbumins.

Sign in / Sign up

Export Citation Format

Share Document