Stability of induced α-glucosidase activity in the absence of inducer

1969 ◽  
Vol 47 (7) ◽  
pp. 677-684 ◽  
Author(s):  
Robert G. Bell
Keyword(s):  
Protein Synthesis ◽  
Enzyme Activity ◽  
Energy Production ◽  
Yeast Cells ◽  
Glucose Medium ◽  
Inhibit Protein Synthesis ◽  
Original Activity ◽  
Glucosidase Activity ◽  
Initial Rise ◽  
Purine Pyrimidine

Yeast cells containing induced α-glucosidase activity lose 10% of the original activity per hour when placed in phosphate buffer – glucose medium. The presence of inducer has no effect on the rate of loss. Induced cells placed in complex medium plus glucose or glycerol show an initial rise in α-glucosidase activity, and then a slow decrease which is accelerated when growth stops. The loss of induced enzyme activity in buffer–glucose medium is inhibited by inhibitors of energy production or protein synthesis whether they are added immediately or 2 or 4 h after suspension of cells in the medium. The ability of the inhibitors to block the loss of induced enzyme activity is correlated with their ability to inhibit protein synthesis. Ammonium sulfate inhibits the loss of α-glucosidase activity after a lag but amino acid or purine–pyrimidine mixtures do not. The loss of induced enzyme activity in cell-free supernatant solutions is less than 2% of the original activity per hour at 30°.

Glucose-dependent control of leucine metabolism by leucyl-tRNA synthetase 1

Science ◽  
2019 ◽  
pp. eaau2753 ◽  
Author(s):  
Ina Yoon ◽  
Miso Nam ◽  
Hoi Kyoung Kim ◽  
Hee-Sun Moon ◽  
Sungmin Kim ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Energy Production ◽  
Trna Synthetase ◽  
Glucose Starvation ◽  
Catabolic Pathway ◽  
Inhibit Protein Synthesis ◽  
Support Cell ◽  
Save Energy

Despite the importance of glucose and amino acids for energy metabolism, interactions between the two nutrients are not well understood. We provide evidence for a role of leucyl-tRNA synthetase 1 (LARS1) in glucose-dependent control of leucine usage. Upon glucose starvation, LARS1 was phosphorylated by Unc-51 like autophagy activating kinase 1 (ULK1) at the residues crucial for leucine-binding. The phosphorylated LARS1 showed decreased leucine-binding, which may inhibit protein synthesis and help save energy. Leucine, not used to anabolic process, may be available to catabolic pathway for energy generation. The LARS1-mediated changes in leucine utilization might help support cell survival deprived of glucose. Thus, dependent on the availability of glucose, LARS1 may help regulate whether leucine is used for protein synthesis or energy production.

scholarly journals The Effects of ZnO Nanoparticles in Combination with Alcohol on Biosynthetic Potential of Saccharomyces cerevisiae

2017 ◽  
Vol 21 (2) ◽  
pp. 19-24
Author(s):  
Natalia Chiseliţa ◽  
Agafia Usatii ◽  
Nadejda Efremova
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Biomass Production ◽  
Zno Nanoparticles ◽  
Yeast Strain ◽  
Culture Medium ◽  
Inhibit Protein Synthesis ◽  
Maximum Value ◽  
Directed Synthesis

Abstract This paper reports about experimental results concerning the influence of 30 nm ZnO nanoparticles on biomass, carbohydrates, β-glucans, proteins accumulation and catalase enzyme activity at Saccharomyces cerevisiae CNMN-Y-20 yeast strain exposed to alcohol action. Alcohol in concentrations of 2%, 5% and 10% added to culture medium has been reported to stimulate β-glucans biosynthesis and to inhibit protein synthesis. Low biomass production, with 71% less that control, was detected in the experiments with 10% alcohol. ZnO nanoparticles in combination with alcohol do not offer sufficient protection for the proteins biosynthesis, but efficiently protect the carbohydrates and β-glucans biosynthetic processes, which contents in the biomass are with 16.6% and 19.9% higher than control, respectively. The maximum value of β-glucans content was established in case of cultivation of selected yeast strain on YPD medium supplemented with 5 mg/L nanoparticles ZnO and 2% alcohol. The obtained results allowed the elaboration of new procedure for directed synthesis of β-glucans that contributed to an increase of this component with 30.7%, compared to control.

INHIBITION OF THYROGLOBULIN BIOSYNTHESIS AND DEGRADATION BY EXCESS IODIDE. SYNERGISM WITH LITHIUM

1976 ◽  
Vol 81 (2) ◽  
pp. 495-506 ◽  
Author(s):  
A. Radvila ◽  
R. Roost ◽  
H. Bürgi ◽  
H. Kohler ◽  
H. Studer
Keyword(s):  
Protein Synthesis ◽  
Thyroid Gland ◽  
Inhibitory Action ◽  
Inhibit Protein Synthesis ◽  
Thyrotrophic Hormone ◽  
Thyroid Glands ◽  
Pre Treatment ◽  
Excess Iodide ◽  
Kidney Liver

ABSTRACT Lithium and excess iodide inhibit the release of thyroid hormone from preformed stores. We thus tested the hypothesis that this was due to an inhibition of thyroglobulin breakdown. Rats were pre-treated with propylthiouracil (PTU) for 3 weeks in order to deplete their thyroids of thyroglobulin. While the PTU was continued, lithium chloride (0.25 mEq./100 g weight) or potassium iodide (3 mg per rat) were injected every 12 h for 3 days. Thereafter the thyroglobulin content in thyroid gland homogenates was measured. PTU pre-treatment lowered the thyroglobulin content from 4.21 to 0.22 mg/100 mg gland. Lithium caused a marked re-accumulation of thyroglobulin to 0.60 mg/100 mg within 3 days. While iodide alone had only a borderline effect, it markedly potentiated the action of lithium and a combination of the two drugs increased the thyroglobulin content to 1.04 mg/100 mg. Thyroxine was injected into similarly pre-treated animals to suppress secretion of thyrotrophic hormone. This markedly inhibited the proteolysis of thyroglobulin and 1.3 mg/100 mg gland accumulated after 3 days. Excess iodide, given in addition to thyroxine, decreased the amount of thyroglobulin accumulated to 0.75 mg/100 mg gland. To study whether this could be explained by an inhibitory action of iodide on thyroglobulin biosynthesis, thyroid glands from animals treated with excess iodide were incubated in vitro in the presence of 0.2 mm iodide for 3 h. Iodide decreased the incorporation of radioactive leucine into total thyroidal protein and into thyroglobulin by 25 and 35 % respectively. Iodide did not inhibit protein synthesis in the kidney, liver or muscle tissue. Thus, large doses of iodide selectively inhibit thyroglobulin biosynthesis.

scholarly journals The role of mitochondrial bioenergetics and reactive oxygen species in coronary collateral growth

2013 ◽  
Vol 305 (9) ◽  
pp. H1275-H1280 ◽  
Author(s):  
Yuh Fen Pung ◽  
Wai Johnn Sam ◽  
James P. Hardwick ◽  
Liya Yin ◽  
Vahagn Ohanyan ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Protein Synthesis ◽  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Energy Production ◽  
Phenotypic Switching ◽  
Oxygen Species ◽  
Coronary Collateral ◽  
Collateral Growth

Coronary collateral growth is a process involving coordination between growth factors expressed in response to ischemia and mechanical forces. Underlying this response is proliferation of vascular smooth muscle and endothelial cells, resulting in an enlargement in the caliber of arterial-arterial anastomoses, i.e., a collateral vessel, sometimes as much as an order of magnitude. An integral element of this cell proliferation is the process known as phenotypic switching in which cells of a particular phenotype, e.g., contractile vascular smooth muscle, must change their phenotype to proliferate. Phenotypic switching requires that protein synthesis occurs and different kinase signaling pathways become activated, necessitating energy to make the switch. Moreover, kinases, using ATP to phosphorylate their targets, have an energy requirement themselves. Mitochondria play a key role in the energy production that enables phenotypic switching, but under conditions where mitochondrial energy production is constrained, e.g., mitochondrial oxidative stress, this switch is impaired. In addition, we discuss the potential importance of uncoupling proteins as modulators of mitochondrial reactive oxygen species production and bioenergetics, as well as the role of AMP kinase as an energy sensor upstream of mammalian target of rapamycin, the master regulator of protein synthesis.

scholarly journals Induction of carnitine acetyltransferase by clofibrate in rat liver

1981 ◽  
Vol 194 (1) ◽  
pp. 249-255 ◽  
Author(s):  
B Mittal ◽  
C K R Kurup
Keyword(s):  
Protein Synthesis ◽  
Enzyme Activity ◽  
Rat Liver ◽  
Time Lag ◽  
Mitochondrial Protein ◽  
Carnitine Acetyltransferase ◽  
Enzyme Protein ◽  
General Protein Synthesis ◽  
Liver And Kidney ◽  
General Protein

Administration of the anti-hypercholesterolaemic drug clofibrate to the rat increases the activity of carnitine acetyltransferase (acetyl-CoA-carnitine O-acetyltransferase, EC 2.3.1.7) in liver and kidney. The drug-mediated increase in enzyme activity in hepatic mitochondria shows a time lag during which the activity increases in the microsomal and peroxisomal fractions. The enzyme induced in the particulate fractions is identical with one normally present in mitochondria. The increase in enzyme activity is prevented by inhibitors of RNA and general protein synthesis. Mitochondrial protein-synthetic machinery does not appear to be involved in the process. Immunoprecipitation shows increased concentration of the enzyme protein in hepatic mitochondria isolated from drug-treated animals. In these animals, the rate of synthesis of the enzyme is increased 7-fold.

scholarly journals Increase in alkaline phosphatase activity in calvaria cells cultured with diphosphonates

1979 ◽  
Vol 183 (1) ◽  
pp. 73-81 ◽  
Author(s):  
R Felix ◽  
H Fleisch
Keyword(s):  
Alkaline Phosphatase ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Phosphatase Activity ◽  
Alkaline Phosphatase Activity ◽  
Heat Inactivation ◽  
High Concentration ◽  
Control Value ◽  
Km Value ◽  
Inhibitor Of Protein Synthesis

1. Dichloromethanediphosphonate and to a lesser degree 1-hydroxyethane-1,1-diphosphonate, two compounds characterized by a P-C-P bond, increased the alkaline phosphatase activity of cultured rat calvaria cells up to 30 times in a dose-dependent fashion. 2. Both diphosphonates also slightly inhibited the protein synthesis in these cells. 3. Thymidine, an inhibitor of cell division, did not inhibit the induction of the enzyme, indicating that the increase in enzyme activity was not due to the formation of a specific population of cells with high alkaline phosphatase activity. 4. The effect on alkaline phosphatase was suppressed by the addition of cycloheximide, an inhibitor of protein synthesis. 5. After subculturing the stimulated cells in medium without diphosphonates, the enzyme activity fell almost to the control value. 6. Bovine parathyrin diminished the enzyme activity of the control cells and the cells treated with dichloromethanediphosphonate; however, at high concentration the effect of parathyrin was greater on the diphosphonate-treated cells than on the control cells. 7. The electrophoretic behaviour, heat inactivation, inhibition by bromotetramisole or by phenylalanine, and the Km value of the induced enzyme were identical with that of the control enzyme.

The effects of D- and L-threo-chloramphenicol on the early development of the chick embryo

Development ◽  
1965 ◽  
Vol 13 (3) ◽  
pp. 341-356
Author(s):  
F. S. Billett ◽  
Rosalba Collini ◽  
Louie Hamilton
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Chick Embryo ◽  
Messenger Rna ◽  
Mammalian Cells ◽  
Animal Cells ◽  
Inhibit Protein Synthesis ◽  
Acid Complex ◽  
Amino Acid Complex ◽  
Bacterial Systems

In many bacterial systems chloramphenicol has been shown to inhibit protein synthesis (Hahn & Wisseman, 1951; Gale & Folkes, 1953). The precise mechanism of this inhibition is not clear, although the evidence suggests that the interaction of the soluble RNA-amino acid complex with the ribosomes is prevented because the attachment of the messenger RNA to the ribosomes is itself impaired (Lacks & Gros, 1959; Nathans & Lipman, 1961; Jardetsky & Julian, 1964; Julian & Jardetsky, 1964). In contrast to its effect on bacterial systems, chloramphenicol has been reported to have little or no action on the protein synthesis by cell-free extracts of mammalian cells (Rendi, 1959; Ehrenstein & Lipmann, 1961). A basis for this resistance has been proposed by Vazquez (1964), who finds that whereas bacterial ribosomes bind chloramphenicol, ribosomes from other organisms do not. Nevertheless, it cannot be stated with any confidence that chloramphenicol has no effect on the protein synthesis of animal cells.

The route of entry of cytoplasmically synthesized proteins into chloroplasts of algae possessing chloroplast ER

1979 ◽  
Vol 35 (1) ◽  
pp. 253-266
Author(s):  
S.P. Gibbs
Keyword(s):  
Protein Synthesis ◽  
Nuclear Envelope ◽  
Outer Membrane ◽  
Chloroplast Envelope ◽  
Inhibit Protein Synthesis ◽  
Ochromonas Danica ◽  
Plastid Proteins ◽  
Regular Network ◽  
Cytoplasmic Ribosomes ◽  
Plastid Ribosomes

In 8 classes of algae, namely the Cryptophyceae, Raphidophyceae, Haptophyceae, Chrysophyceae, Bacillariophyceae, Xanthophyceae, Eustigmatophyceae and Phaeophyceae, the chloroplasts, in addition to being surrounded by a double-membraned chloroplast envelope, are also enclosed by a cisterna of endoplasmic reticulum called the chloroplast ER. Often this ER cisterna is continuous with the outher membrane of the nuclear envelope in such a manner that the nuclear envelope forms a part of the ER sac enclosing the chloroplast. In all these classes of algae except the Cryptophyceae, a regular network of tubules and vesicles, named the periplastidal reticulum, is present at a specific location between the chloroplast envelope and the chloroplast ER. In the Cryptophyceae, scattered vesicles are found between the chloroplast envelope and the chloroplast ER. Ribosomes which have been shown to be arranged to polysomes are found on the outer membrane of the chloroplast ER. It is proposed that nuclear-coded proteins which are destined for the chloroplast are synthesized on these polysomes, passing during synthesis into the lumen of the ER cisterna. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles then fuse with the outer membrane of the chloroplast envelope thereby delivering their contents to the lumen of the chloroplast envelope. Proteins then cross the inner membrane of the chloroplast envelope in an as yet unknown manner. Experimental evidence for this hypothesis comes from studies on Ochromonas danica using chloramphenicol and spectinomycin, which inhibit protein synthesis on plastid ribosomes, and cycloheximide, which inhibits protein synthesis on cytoplasmic ribosomes. In cells of Ochromonas exposed to chloramphenicol or spectinomycin, the periplastidal reticulum proliferates markedly becoming several layers thick. Presumably this build up of periplastidal reticulum occurs because the transport of cytoplasmically synthesized plastid proteins is slowed down when protein synthesis in the chloroplast is inhibited. Conversely, when cells of Ochromonas are treated with cycloheximide, there is a reduction in the amount of periplastidal reticulum presumably because there are no cytoplasmically synthesized proteins to be transported into the chloroplast.

Effect of temperature and pH on the production, activity, and stability of α-amylase from Bacillus subtilis V37

2021 ◽  
Vol 66 (1) ◽  
pp. 72-79
Author(s):  
Thuoc Doan Van ◽  
Hung Nguyen Phuc
Keyword(s):  
Enzyme Activity ◽  
Bacillus Subtilis ◽  
Animal Feed ◽  
Culture Conditions ◽  
Effect Of Temperature ◽  
Physical Parameters ◽  
Original Activity ◽  
Optimum Ph ◽  
Production Activity ◽  
Ph Range

The effect of physical parameters such as temperature and pH on the production, activity, and stability of α-amylase from Bacillus subtilis V37 was investigated. The results indicated that the optimum culture conditions for enzyme activity were pH 7.0 and 35 oC. The optimum pH and temperature for enzyme activity were 6.0 and 70 oC. The crude enzyme was found to be stable in the pH range of 5.0 to 7.0. The enzyme was stable for 1 h at a temperature from 30 to 80 oC; nearly 100% of enzyme activity remained at temperatures of 30 - 40 oC, and about 34% of original activity remained at a temperature of 80 oC. These features demonstrated that α-amylase from B. subtilis V37 can be applied in many areas such as the food, fermentation, and animal feed industries.

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