THE WHEAT LEAF PHOSPHATASES: VI. SOME PROPERTIES OF THE ENZYME SYSTEM HYDROLYZING ADENOSINE-5′-PHOSPHATE AND PHENOLPHTHALEIN DIPHOSPHATE IN CRUDE JUICE PREPARATIONS

1963 ◽  
Vol 41 (1) ◽  
pp. 1275-1281 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Enzyme System ◽  
The Other ◽  
Enzymic Hydrolysis ◽  
Ph Optimum ◽  
Wheat Leaf ◽  
Hydrolysis Of ◽  
Leaf Juice

At least two enzymes are probably involved in the hydrolysis of mixtures of β-glycerophosphate, phenolphthalein diphosphate, and adenosine-5′-phosphate. One enzyme is primarily responsible for the hydrolysis of β-glycerophosphate whereas the other enzyme hydrolyzes adenosine-5′-phosphate and phenolphthalein diphosphate but has little activity on β-glycerophosphate.The liberation of orthophosphate from adenosine-5′-phosphate and phenolphthalein diphosphate by the enzyme in wheat leaf juice is inhibited by 0.005 M adenosine but not by 0.02 M phosphate. The inhibition of this enzyme by fluoride is markedly smaller than the inhibition of β-glycerophosphatase. The enzyme that hydrolyzes phenolphthalein diphosphate transfers phosphate from phenolphthalein diphosphate to adenosine to form adenosine-5′-phosphate.Experiments on the pH optimum for the enzymic hydrolysis of both adenosine-5′-phosphate and phenolphthalein diphosphate by undialyzed and dialyzed juice preparations with or without added Mg++ suggest that there may be more than one enzyme with different pH optima acting on both adenosine-5′-phosphate and phenolphthalein diphosphate.

THE WHEAT LEAF PHOSPHATASES: VI. SOME PROPERTIES OF THE ENZYME SYSTEM HYDROLYZING ADENOSINE-5′-PHOSPHATE AND PHENOLPHTHALEIN DIPHOSPHATE IN CRUDE JUICE PREPARATIONS

1963 ◽  
Vol 41 (5) ◽  
pp. 1275-1281 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Enzyme System ◽  
The Other ◽  
Enzymic Hydrolysis ◽  
Ph Optimum ◽  
Wheat Leaf ◽  
Hydrolysis Of ◽  
Leaf Juice

At least two enzymes are probably involved in the hydrolysis of mixtures of β-glycerophosphate, phenolphthalein diphosphate, and adenosine-5′-phosphate. One enzyme is primarily responsible for the hydrolysis of β-glycerophosphate whereas the other enzyme hydrolyzes adenosine-5′-phosphate and phenolphthalein diphosphate but has little activity on β-glycerophosphate.The liberation of orthophosphate from adenosine-5′-phosphate and phenolphthalein diphosphate by the enzyme in wheat leaf juice is inhibited by 0.005 M adenosine but not by 0.02 M phosphate. The inhibition of this enzyme by fluoride is markedly smaller than the inhibition of β-glycerophosphatase. The enzyme that hydrolyzes phenolphthalein diphosphate transfers phosphate from phenolphthalein diphosphate to adenosine to form adenosine-5′-phosphate.Experiments on the pH optimum for the enzymic hydrolysis of both adenosine-5′-phosphate and phenolphthalein diphosphate by undialyzed and dialyzed juice preparations with or without added Mg++ suggest that there may be more than one enzyme with different pH optima acting on both adenosine-5′-phosphate and phenolphthalein diphosphate.

HYDROLYSIS OF SOME DEOXYRIBONUCLEOSIDES BY WHEAT LEAF JUICE

1961 ◽  
Vol 39 (9) ◽  
pp. 1333-1334
Author(s):  
D. W. A. Roberts
Keyword(s):  
Wheat Leaf ◽  
Hydrolysis Of ◽  
Leaf Juice

Enzymes present in wheat leaf juice convert deoxyadenosine into adenine and deoxyribose, deoxycytidine into deoxyuridine, and 5-methyldeoxycytidine into thymidine.

scholarly journals The Comparative Metabolism of Some Substituted Phenyl-N-Methylcarbamate Insecticides

2021 ◽  
Author(s):  
◽  
Philip Geoffrey Charles Douch
Keyword(s):  
Musca Domestica ◽  
Enzyme System ◽  
Enzymic Hydrolysis ◽  
Selective Toxicity ◽  
Mouse Blood ◽  
Carbamate Insecticides ◽  
Comparative Metabolism ◽  
Costelytra Zealandica ◽  
Oxidative Products ◽  
Hydrolysis Of

<p>1. The metabolism of the N-methylcarbamates of 3-tertbutylphenol; 3,5-ditertbutylphenol; and 2-isopropoxyphenol was investigated in insects and mammals. 2. The major degradative pathway in enzyme systems from insects and mice was oxidative. The major metabolites from tertbutyl substituted phenyl-N-methylcarbamates were N-hydroxymethyl derivatives and tertbutanol derivatives. Baygon yielded N-hydroxymethyl, ring hydroxyl and O-dealkyl derivatives as major metabolites. 3. The rates of oxidation of the three insecticides in each enzyme system were similar. 4. Oxidation was inhibited by piperonyl butoxide and Metopirone, apparent I50 for singly oxidised metabolites was 10-4 M, and for metabolites with two oxidations 10-5M. 5. Enzymic hydrolysis of carbamate insecticides required reduced cofactor in insect and mouse systems. Mouse blood did not effect hydrolysis. 6. A wide variation of oxidising ability was found in live insects. Musca domestica was most active, Tenebrio molitor and Costelytra zealandica were least active. 7. Insecticide synergists reduce insects' ability to oxidise Baygon to acetone. 8. Musca domestica and Lucilia sericata larvae oxidised carbamate insecticides slower than the adult forms. 9. Mice excrete 3-tertbutylphenyl-N-methylcarbamate as phenolic metabolites, with only minor oxidative products. 10. Different rates of metabolism among insects could account for the selective toxicity of aryl-N-methylcarbamates.</p>

THE WHEAT LEAF PHOSPHATASES: V. SOME PROPERTIES OF THE ENZYME SYSTEM HYDROLYZING β-GLYCEROPHOSPHATE IN CRUDE JUICE PREPARATIONS

1963 ◽  
Vol 41 (1) ◽  
pp. 113-120 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Enzyme System ◽  
Enzyme Concentration ◽  
Ph Optimum ◽  
Wheat Leaf ◽  
Excess Substrate

Wheat leaf press juice contains an enzyme that has β-glycerophosphatase activity, which has a pH optimum close to pH 5.7. The enzyme is inhibited by orthophosphate, pyrophosphate, and 10−4 M fluoride. Fluoride inhibition can be abolished by thorough dialysis. Fluoride partially protects the enzyme from denaturation by heat.Enzyme kinetics shows that the log of the enzyme concentration is proportional to the log of the rate of liberation of orthophosphate from the substrate in the presence of excess substrate (0.2 M to 0.6 M) at pH 5.7. This observation can be used for quantitation of the enzyme.

THE WHEAT LEAF PHOSPHATASES: V. SOME PROPERTIES OF THE ENZYME SYSTEM HYDROLYZING β-GLYCEROPHOSPHATE IN CRUDE JUICE PREPARATIONS

1963 ◽  
Vol 41 (1) ◽  
pp. 113-120 ◽  
Author(s):  
D. W. A. Roberts
Keyword(s):  
Enzyme System ◽  
Enzyme Concentration ◽  
Ph Optimum ◽  
Wheat Leaf ◽  
Excess Substrate

Wheat leaf press juice contains an enzyme that has β-glycerophosphatase activity, which has a pH optimum close to pH 5.7. The enzyme is inhibited by orthophosphate, pyrophosphate, and 10−4 M fluoride. Fluoride inhibition can be abolished by thorough dialysis. Fluoride partially protects the enzyme from denaturation by heat.Enzyme kinetics shows that the log of the enzyme concentration is proportional to the log of the rate of liberation of orthophosphate from the substrate in the presence of excess substrate (0.2 M to 0.6 M) at pH 5.7. This observation can be used for quantitation of the enzyme.

scholarly journals The hydrolysis of monolayers of phosphatidyl-[Me−14C]choline by phospholipase D

1969 ◽  
Vol 113 (4) ◽  
pp. 697-705 ◽  
Author(s):  
R. H. Quarles ◽  
R. M. C. Dawson
Keyword(s):  
Phosphatidic Acid ◽  
Phospholipase D ◽  
High Pressures ◽  
Specific Radioactivity ◽  
Maximal Activity ◽  
Enzymic Hydrolysis ◽  
Ph Optimum ◽  
High Specific Radioactivity ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of

1. The hydrolysis of monolayers of phosphatidyl[Me−14C]choline at the air/water interface by phospholipase D (phosphatidylcholine phosphatidohydrolase) was investigated by a surface-radioactivity technique by using a flow counter. 2. Phosphatidylcholine of high specific radioactivity was prepared biosynthetically in good yield from [Me−14C]choline by using Saccharomyces cerevisiae. 3. At initial monolayer pressures between 12 and 25 dynes/cm. the hydrolysis occurred in two stages, an initial slow hydrolysis followed by a rapid hydrolysis. Below 3dynes/cm. and above 28dynes/cm. no enzymic hydrolysis of pure phosphatidylcholine monolayers could be detected. 4. The rapid hydrolysis was proportional to the enzyme concentration in the subphase, its pH optimum was 6·6, and 0·2mm-Ca2+ was required for maximal activity. 5. Hydrolysis of the film was accompanied by a pronounced fall in the surface pressure even though the phosphatidic acid formed did not leave the film. When the pressure fell to low values the hydrolysis ceased even if the film was only partially hydrolysed. 6. Above monolayer pressures of 28dynes/cm. enzymic hydrolysis could be initiated by inclusion of phosphatidic acid (and less effectively stearyl hydrogen sulphate) in the film, although the rates were not appreciably higher than those observed at 25dynes/cm. with a pure phosphatidylcholine film. 7. The initiation of the hydrolysis by phosphatidic acid was facilitated by the inclusion of high Ca2+ concentrations and certain carboxylic acid buffer anions in the subphase, although these did not activate by themselves. 8. The initiation of the hydrolysis at high pressures could not be related to any change in the surface potential brought about by the addition of the long-chain anions to the film, nor could it be ascribed to a surface dilution effect. 9. The results are discussed in relation to previous studies on the hydrolysis of phosphatidylcholine particles by the enzyme and also similar investigations on phosphatidylcholine monolayers with other phospholipases.

Enzymic hydrolysis of the potassium chloride soluble fraction of carrageenan: properties of "λ-carrageenases" from Pseudomonas carrageenovora

1973 ◽  
Vol 19 (7) ◽  
pp. 779-788 ◽  
Author(s):  
K. H. Johnston ◽  
E. L. McCandless
Keyword(s):  
Soluble Fraction ◽  
Reducing Sugar ◽  
Chondrus Crispus ◽  
Enzymic Hydrolysis ◽  
Temperature Optimum ◽  
Ph Optimum ◽  
Specific Viscosity ◽  
Chromatographic Resolution ◽  
Fraction I ◽  
Hydrolysis Of

An enzyme complex which hydrolyzed the KCl soluble carrageenan extracted from the red alga Chondrus crispus has been isolated from the cell-free medium of a culture of Pseudomonas carrageenovora grown on this polysaccharide. Three hydrolases could be separated. Fraction I, which caused a rapid decrease in the specific viscosity of the polysaccharide preparation with only minimal release of reducing sugar, could be distinguished from fraction II chromatographically on Sephadex G-100 and electrophoretically on agarose gel. Fraction IIa caused release of reducing sugar at pH 6.2, which activity was depressed at pH 7.5. Fraction IIb exhibited viscometric activity only at both pH 6.2 and pH 7.5. Fraction IIa had a sharp pH optimum at pH 6.2 and a temperature optimum at 28°. All hydrolases were inactivated by freezing, by dialysis against distilled water, by heating at 35° for 30 min, and by Hg2+ and 0.0001 mM EDTA. When fraction II (a and b) isolated after chromatographic resolution on Sephadex G-100 was incubated at pH 6.2 with KCl soluble carrageenan from C. crispus, products which had Rgal values of 0.74 and 0.17 were detected, were sulfated, and contained no 3,6-anhydrogalactose.

A crystallographic study of the oxidation of lysozyme by iodine

1967 ◽  
Vol 167 (1009) ◽  
pp. 435-438 ◽  
Keyword(s):  
Active Site ◽  
The Other ◽  
Enzymic Hydrolysis ◽  
Substrate Modification ◽  
Crystallographic Study ◽  
Competitive Inhibitors ◽  
Plausible Hypothesis ◽  
The One ◽  
Hydrolysis Of ◽  
Tryptophanyl Residue

The crystallographic examinations of the lysozyme molecule, and of the complexes of lysozyme with competitive inhibitors, have resulted in the identification of the active site and in a plausible hypothesis for its activity as described in the previous papers at this meeting (Blake, Mair, North, Phillips & Sarma, p. 365; Blake, Johnson, Mair, North, Phillips & Sarma, p. 378). The active site includes three tryptophanyl residues (62, 63 and 108) which appear to be involved in the binding of the substrate. Modification of some or all of these residues may provide further evidence of their function in the activity of the enzyme (see figure 19 a of Blake et al ., p. 384). Hartdegen & Rupley (1964) showed that the action of small amounts of triiodide produced two modified lysozymes. One product, containing iodine, was enzymically active, while the other which contained no iodine was inactive. Enzymic hydrolysis of the latter product revealed that it had one less tryptophanyl residue than the native enzyme. Hartdegen & Rupley were not able, however, to show which of the six tryptophanyl residues in the lysozyme molecule was the one uniquely reactive to iodine, but they were able to show that it was part of, or near, the active site.

scholarly journals The Comparative Metabolism of Some Substituted Phenyl-N-Methylcarbamate Insecticides

2021 ◽  
Author(s):  
◽  
Philip Geoffrey Charles Douch
Keyword(s):  
Musca Domestica ◽  
Enzyme System ◽  
Enzymic Hydrolysis ◽  
Selective Toxicity ◽  
Mouse Blood ◽  
Carbamate Insecticides ◽  
Comparative Metabolism ◽  
Costelytra Zealandica ◽  
Oxidative Products ◽  
Hydrolysis Of

<p>1. The metabolism of the N-methylcarbamates of 3-tertbutylphenol; 3,5-ditertbutylphenol; and 2-isopropoxyphenol was investigated in insects and mammals. 2. The major degradative pathway in enzyme systems from insects and mice was oxidative. The major metabolites from tertbutyl substituted phenyl-N-methylcarbamates were N-hydroxymethyl derivatives and tertbutanol derivatives. Baygon yielded N-hydroxymethyl, ring hydroxyl and O-dealkyl derivatives as major metabolites. 3. The rates of oxidation of the three insecticides in each enzyme system were similar. 4. Oxidation was inhibited by piperonyl butoxide and Metopirone, apparent I50 for singly oxidised metabolites was 10-4 M, and for metabolites with two oxidations 10-5M. 5. Enzymic hydrolysis of carbamate insecticides required reduced cofactor in insect and mouse systems. Mouse blood did not effect hydrolysis. 6. A wide variation of oxidising ability was found in live insects. Musca domestica was most active, Tenebrio molitor and Costelytra zealandica were least active. 7. Insecticide synergists reduce insects' ability to oxidise Baygon to acetone. 8. Musca domestica and Lucilia sericata larvae oxidised carbamate insecticides slower than the adult forms. 9. Mice excrete 3-tertbutylphenyl-N-methylcarbamate as phenolic metabolites, with only minor oxidative products. 10. Different rates of metabolism among insects could account for the selective toxicity of aryl-N-methylcarbamates.</p>

scholarly journals Hydrolysis of αs2-casein in solution by chymosin, plasmin, trypsin and Lactobacillus-proteinases

1993 ◽  
Vol 2 (2) ◽  
pp. 133-139
Author(s):  
Anne Pihlanto-Leppälä ◽  
Eero Pahkala ◽  
Minna Kahala ◽  
Veijo Antila
Keyword(s):  
Proteolytic Activity ◽  
Lactobacillus Helveticus ◽  
The Other ◽  
Cell Free Extract ◽  
Enzymic Hydrolysis ◽  
The Third ◽  
Other Hand ◽  
Almost All ◽  
Hydrolysis Of

The aim of this study was to examine the enzymic hydrolysis of αs2-casein by isolating and identifying the released peptides. The enzymes applied in the study were chymosin, plasmin and trypsin as well as cell free extracts from three strains of Lactobacillus helveticus and nine strains of L. casei. The findings showed that chymosin had weak proteolytic activity on αs2-casein. Plasmin, on the other hand, released numerous peptides under the used conditions. The majority of the identified fragments were released from the C terminal end of the substrate. Plasmin hydrolysed mainly Lys-X bonds. The third enzyme, trypsin, hydrolysed several bonds of αs2-casein. Peptides were released from almost all regions of the protein. Trypsin acted on the carboxyl sides of arginyl and lysyl residues. Cell free extract of lactobacilli had little activity on αs2-casein.

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