Barbiturate-induced α-amylase synthesis in barley endosperm

1970 ◽  
Vol 48 (11) ◽  
pp. 1981-1988 ◽  
Author(s):  
G. A. White
Keyword(s):  
Enzyme Activity ◽  
Gibberellic Acid ◽  
Barbituric Acid ◽  
De Novo ◽  
Carbonyl Oxygen ◽  
De Novo Synthesis ◽  
Barley Endosperm ◽  
Optimal Activity ◽  
Mammalian Liver ◽  
Kinetics Of

Phenobarbital has been found to promote the synthesis and secretion of α-amylase by embryoless barley seeds. Optimal activity was observed at a phenobarbital concentration of 1.0 mM, which promoted 39–82% (average, 57%) as much α-amylase formation as did saturating concentrations of gibberellic acid (GA3). Barley half-seeds incubated with 0.1 mM phenobarbital secreted as much protein as did those treated with 1.0 μM GA3. The kinetics of release of α-amylase from half-seeds incubated with either phenobarbital or GA3 appeared identical. Phenobarbital likely induces a de novo synthesis of α-amylase since the increase in enzyme activity was almost totally blocked by cycloheximide and 6-methylpurine. Besides phenobarbital, only cyclobarbital, amytal, hexobarbital, and thiopental showed activity among a large number of barbiturates and related drugs which were tested. In the phenobarbital molecule, the carbonyl oxygen at position 2 and the hydrogen on the nitrogen at position 3 of the barbituric acid ring are absolute requirements for activity since both 2-desoxyphenobarbital and methylphenobarbital elicited no response. Substitution of the phenyl moiety of phenobarbital with any group other than a cyclohexenyl (cyclobarbital) or an isoamyl (amytal) gave complete inactivity. Some possible mechanisms for the mode of action of phenobarbital in the barley endosperm system are discussed with particular reference to what is currently known regarding the inductive action of this barbiturate in mammalian liver.

Activités physiologiques de l'ochracine, synthétisée par Septoria nodorum, sur la croissance de plantules de riz et sur la synthèse ‘de novo’ des alpha-amylases par les couches à aleurone du caryopse de blé. Interaction avec l'acide gibbérellique

1979 ◽  
Vol 57 (6) ◽  
pp. 561-567 ◽  
Author(s):  
G. Touraud ◽  
J. F. Bousquet
Keyword(s):  
Synergistic Effect ◽  
Gibberellic Acid ◽  
De Novo ◽  
Pathogenic Fungus ◽  
Septoria Nodorum ◽  
De Novo Synthesis ◽  
Rice Seedlings ◽  
Culture Filtrates ◽  
Increased Sensitivity ◽  
Tissue Permeability

Ochracine was isolated from culture filtrates of Septoria nodorum Berk. (Berk.), a pathogenic fungus of wheat. At concentrations ranging from 25 μg/mL it inhibited the growth of wheat and rice seedlings and the 'de novo' synthesis of α-amylases by the aleurone layers of wheat. These effects were not reversed by increased concentrations of gibberellic acid.Between 2.5 and 10 μg/mL, ochracine exhibited a synergistic effect with exogenous gibberellic acid on the same physiological phenomena. For these last concentrations, the results suggest an increased sensitivity of rice seedlings and wheat aleurone layers to exogenous gibberellic acid as a result of changes in tissue permeability.

Thymidylate kinase from Acetabularia. II. Regulation during the life cycle

1983 ◽  
Vol 64 (1) ◽  
pp. 27-36
Author(s):  
E.J. de Groot ◽  
H.G. Schweiger
Keyword(s):  
Enzyme Activity ◽  
Life Cycle ◽  
Kinase Activity ◽  
De Novo ◽  
Nuclear Genome ◽  
De Novo Synthesis ◽  
Cell Extracts ◽  
Phase Regulation ◽  
Generative Phase ◽  
Low Activity

The activity of dTMP kinase (EC 2.7.4.9) was estimated during the development of Acetabularia. Enzyme activity was increased at the beginning of the generative phase. Regulation of the dTMP kinase activity was observed even in the absence of the nucleus. More than 30 days after enucleation the enzyme activity increased two- to threefold. The increase in activity was inhibited by puromycin and cycloheximide but not by rifampicin and chloramphenicol. These results indicate that the enzyme is coded by the nuclear genome and translated on 80 S ribosomes. From mixing experiments with low-activity and high-activity cell extracts it is concluded that the regulation is due to de novo synthesis of the enzyme.

Screening of Basidiomycetes and Ascomycetes for Plant Growth Regulating Substances. Introduction of the Gibberellic Acid Induced de-novo Synthesis of Hydrolytic Enzymes in Embryoless Seeds of Triticum aestivum as Test System

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1093-1098 ◽  
Author(s):  
Ralf Hautzel ◽  
Heidrun Anke
Keyword(s):  
Triticum Aestivum ◽  
Plant Growth ◽  
Gibberellic Acid ◽  
De Novo ◽  
Hydrolytic Enzymes ◽  
Test System ◽  
Active Principle ◽  
De Novo Synthesis ◽  
Plant Growth Regulating Substances

Abstract A new test system for the detection of plant growth regulating activities was successfully employed. In a screening for inhibitors of the gibberellic acid controlled synthesis of hydrolytic enzymes in embryoless wheat seeds (Triticum aestivum) 160 cultures of ascomycetes and basi­diomycetes were tested. In the extracts of two cultures inhibitory activities were detected. From fermentations of a Hypholoma-species (basidiomycetes) 3,5-dichloro-4-methoxybenzyl alcohol was isolated as the active principle. Galiellalactone and two other new phytotoxins were isolated from cultures of the ascomycete Galiella rufa. At concentrations of 50 μg/ml all four compounds inhibited the de-novo synthesis of α-amylases, proteases, and phosphatases. Further investigations on the mode of action revealed, that all four metabolites interfere with early steps of the biosynthetic path­ ways induced by gibberellic acids. In vivo, the germination of the seeds of several plants was inhibited by these compounds.

scholarly journals Kinetics of Crude Peroxidase from the Rind of Watermelon Fruit

2021 ◽  
pp. 20-27
Author(s):  
O. M. Iniaghe ◽  
O. Ibukun ◽  
R. E. Giwa
Keyword(s):  
Enzyme Activity ◽  
Enzyme Assay ◽  
Crude Enzyme ◽  
Redox Mediators ◽  
Alternative Source ◽  
Optimal Activity ◽  
Edo State ◽  
Kinetics Of ◽  
Assay Conditions

Aims: To study the kinetics of crude peroxidase from the rind of watermelon fruit in various assay conditions. Study Design: In vitro enzyme assay. Place and Duration of Study: Department of Biochemistry, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Edo State, Nigeria between October 2015 and January 2016. Methodology: The activity of the crude peroxidase extracted from the rind of watermelon was determined by measuring the rate of oxidation of KI at 25oC in a 3.0 ml reaction mixture which contained 2.3 ml of 25 mM - 400 mM sodium acetate buffer (pH 3.5-6.0), 0.2 ml of 2 mM KI, 0.1ml of the crude peroxidase, and 0.2 ml of varying concentrations of chlorpromazine (0.01 mM - 0.1 mM). In all cases, 0.2 ml of 0.01 mM – 1 mM H2O2 was added last to initiate the reaction. Only one parameter was varied per assay. Assays were done in five replicates. The initial velocity of the crude peroxidase for KI oxidation was determined using the absorbance at 353 nm. Results: The concentration of H2O2 that generated an optimal activity for the crude peroxidase extracted was 0.2 mM, while a pH of 5.5 was optimal for the crude enzyme. The activity of the crude enzyme increased proportionately within a buffer concentration range of 25 mM and 400 mM. Chlorpromazine (0.01 mM - 0.1 mM) proportionately increased the enzyme activity, while promethazine within a range of 0.01 mM and 0.06 mM proportionally increased the enzyme activity. Further increase in promethazine concentration beyond 0.6 mM resulted in a decreased activity of the enzyme. Conclusion: This study suggests that the Rind of watermelon is an alternative source of peroxidase. The activity of this peroxidase can be enhanced by high buffer concentrations in the presence of some redox mediators like promethazine and chlorpromazine at a pH of 5.5.

scholarly journals Effect of enteral glutamine on leucine, phenylalanine and glutamine metabolism in hypercortisolemic subjects

2000 ◽  
Vol 278 (5) ◽  
pp. E817-E824 ◽  
Author(s):  
Sophie Claeyssens ◽  
Corinne Bouteloup-Demange ◽  
Pierre Gachon ◽  
Bernadette Hecketsweiler ◽  
Eric Lerebours ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
De Novo ◽  
Glutamine Metabolism ◽  
Similar Data ◽  
De Novo Synthesis ◽  
Protein Balance ◽  
Fed State ◽  
Significant Change ◽  
Kinetics Of

The effect of enteral Gln on protein and Gln metabolism was investigated during experimental hypercortisolemia. Four groups of subjects that had received corticosteroids and either enteral Gln (0.5 g ⋅ kg−1 ⋅ day−1for 2 days) or isonitrogenous Ala-Gly were studied in a fasted or in a fed state. In either state, enteral Gln, compared with Ala-Gly, induced no statistically significant change in the endogenous rate of Leu appearance, an index of proteolysis, Leu oxidation, and nonoxidative Leu disposal, an index of protein synthesis, as studied by kinetics of [1-13C]Leu. Similar data were obtained from kinetics of [2H5]Phe, resulting in an unchanged protein balance in both cases. In contrast, enteral Gln significantly decreased the endogenous rate of Gln appearance and Gln de novo synthesis in the fed state ( P < 0.05) as estimated by the kinetics of [15N]Gln. This decrease in Gln de novo synthesis induced by Gln could contribute to spare amino acids in hypercatabolic patients.

scholarly journals Cytokinin-induced decrease in ribonuclease activity and initiation of gametophore buds in the protonema of mosses

2015 ◽  
Vol 45 (3) ◽  
pp. 327-334
Author(s):  
Michał Spychała ◽  
Irena Kocz-Zajchert ◽  
Alicja Szwejkowska
Keyword(s):  
Enzyme Activity ◽  
Rna Synthesis ◽  
De Novo ◽  
Ribonuclease Activity ◽  
Rnase Activity ◽  
De Novo Synthesis ◽  
Allosteric Inhibition ◽  
Morphogenetic Effect ◽  
Bud Induction ◽  
Protein And Rna Synthesis

As early as after 4 hours of kinetin treatment a decrease in RNase activity was found in the moss protonema and it was maintained to at least 10 hours. It was shown that this decrease was correlated with the morphogenetic effect of kinetin (bud induction). No allosteric inhibition of RNase toy kinetin could be found. The decrease in enzyme activity was more pronounced When additionally inhibitors of protein and RNA synthesis were used. It is concluded that kinetin affects the RNase rather by an inhibition of de novo synthesis of the enzyme than by an increase of its decomposition by proteases.

scholarly journals Repair of a calcium-dependent adhesive mechanism of embryonic neural retina cells: kinetic and molecular analysis

1983 ◽  
Vol 60 (1) ◽  
pp. 29-49
Author(s):  
R.L. Geller ◽  
J. Lilien
Keyword(s):  
De Novo ◽  
Divalent Cations ◽  
Polyacrylamide Gel Electrophoresis ◽  
Adhesive System ◽  
Neural Retina ◽  
Protein Glycosylation ◽  
De Novo Synthesis ◽  
Calcium Dependent ◽  
Surface Molecules ◽  
Kinetics Of

In this paper, we examine the restitution of a Ca2+-dependent adhesive system of embryonic chick neural retina cells following trypsinization in the absence of divalent cations. The processes involved in the restitution of this system are dissected by monitoring the effects of various drugs, alone and in specific combinations, on the kinetics of adhesion and the morphology of 24-h aggregates. In agreement with prior observations, aggregate formation can be separated into two distinct phases: the formation of adhesions and their ultimate stabilization. The formation of adhesions appears to involve two processes, de novo synthesis of protein and mobilization of an endogenous pool, while stabilization requires de novo synthesis of RNA and protein glycosylation. We also examine the appearance of two cell surface molecules previously implicated in the function of the Ca2+-dependent adhesive system. The cells repaired in the presence or absence of the inhibitors and surface-iodinated at 3 and 5 h. The labelled molecules are then separated by two-dimensional polyacrylamide gel electrophoresis. The appearance of the two molecules, gp130/4.8 and gp70/4.8, is affected by the various drugs in a manner consistent with the effects of these agents on the kinetics of adhesion. These molecules appear to exist in endogenous pools and they are also synthesized de novo during the repair period.

Inhibition of IMP Dehydrogenase by Mycophenolic Acid in Molt F4 Human Malignant Lymphoblasts

1994 ◽  
Vol 31 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Elisabet H Stet ◽  
Ronney A De Abreu ◽  
Jos P M Bökkerink ◽  
Lambert H J Lambooy ◽  
Trade M Vogels-Mentink ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Cell Growth ◽  
Mycophenolic Acid ◽  
De Novo ◽  
Specific Inhibitor ◽  
Guanine Nucleotides ◽  
Guanine Nucleotide ◽  
Inosine Monophosphate Dehydrogenase ◽  
De Novo Synthesis ◽  
Rate Limiting

The effects of inhibition of inosine monophosphate dehydrogenase (IMPDH), the rate-limiting enzyme in guanine nucleotide de novo synthesis, on cell growth, cell viability, endogenous nucleotide concentrations and concentrations of extracellular nucleosides and bases were studied in Molt F4 human malignant lymphoblasts. Mycophenolic acid (MPA) was used as a specific inhibitor of the enzyme activity. IMPDH activity was maximally inhibited with 0–5 μM MPA. After a 2 h exposure of the cells to 0–5 μM MPA, guanine nucleotides were depleted to approximately 50% of control values, whereas 5-phosphoribosyl-1-pyrophosphate levels increased to approximately 200%. Under these conditions, cytotoxicity became obvious after 24 h. Depletion of guanine nucleotides and cytotoxicity were prevented by addition of guanosine to MPA treatment. Daily supplements of guanosine were required to prevent MPA cytotoxicity during the entire incubation period of 72 h. We conclude that depletion of guanine nucleotides, induced by treatment with MPA, induces a severe and rapid cytotoxicity in Molt F4 cells.

scholarly journals Dynamics of Viral RNA Synthesis during Measles Virus Infection

2005 ◽  
Vol 79 (11) ◽  
pp. 6900-6908 ◽  
Author(s):  
Sébastien Plumet ◽  
W. Paul Duprex ◽  
Denis Gerlier
Keyword(s):  
Measles Virus ◽  
Rna Synthesis ◽  
De Novo ◽  
Reference Model ◽  
Viral Rna ◽  
De Novo Synthesis ◽  
A Cell ◽  
Nucleoprotein N ◽  
Kinetics Of

ABSTRACT We propose a reference model of the kinetics of a viral RNA-dependent RNA polymerase (vRdRp) activities and its regulation during infection of eucaryotic cells. After measles virus infects a cell, mRNAs from all genes immediately start to accumulate linearly over the first 5 to 6 h and then exponentially until ∼24 h. The change from a linear to an exponential accumulation correlates with de novo synthesis of vRdRp from the incoming template. Expression of the virus nucleoprotein (N) prior to infection shifts the balance in favor of replication. Conversely, inhibition of protein synthesis by cycloheximide favors the latter. The in vivo elongation speed of the viral polymerase is ∼3 nucleotides/s. A similar profile with fivefold-slower kinetics can be obtained using a recombinant virus expressing a structurally altered polymerase. Finally, virions contain only encapsidated genomic, antigenomic, and 5′-end abortive replication fragment RNAs.

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