scholarly journals Light-regulated allosteric switch enables temporal and subcellular control of enzyme activity

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Mark Shaaya ◽  
Jordan Fauser ◽  
Anastasia Zhurikhina ◽  
Jason E Conage-Pough ◽  
Vincent Huyot ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Tyrosine Kinase ◽  
Enzymatic Activity ◽  
Protein Activity ◽  
Local Regulation ◽  
Regulation Of Activity ◽  
A Cell ◽  
Spatiotemporal Control ◽  
Switch Module ◽  
Stimulation Of

Engineered allosteric regulation of protein activity provides significant advantages for the development of robust and broadly applicable tools. However, the application of allosteric switches in optogenetics has been scarce and suffers from critical limitations. Here, we report an optogenetic approach that utilizes an engineered Light-Regulated (LightR) allosteric switch module to achieve tight spatiotemporal control of enzymatic activity. Using the tyrosine kinase Src as a model, we demonstrate efficient regulation of the kinase and identify temporally distinct signaling responses ranging from seconds to minutes. LightR-Src off-kinetics can be tuned by modulating the LightR photoconversion cycle. A fast cycling variant enables the stimulation of transient pulses and local regulation of activity in a selected region of a cell. The design of the LightR module ensures broad applicability of the tool, as we demonstrate by achieving light-mediated regulation of Abl and bRaf kinases as well as Cre recombinase.

Cinnamate-4-Hydroxyiase in Polyporus hispidus

1973 ◽  
Vol 51 (6) ◽  
pp. 731-734 ◽  
Author(s):  
C. P. Vance ◽  
A. M. D. Nambudiri ◽  
G. H. N. Towers
Keyword(s):  
Enzyme Activity ◽  
Enzymatic Activity ◽  
Microsomal Fraction ◽  
Mitochondrial Fraction ◽  
Maximum Activity ◽  
Coumaric Acid ◽  
Free System ◽  
Optimum Ph ◽  
A Cell ◽  
Plant Enzyme

A cell-free system capable of hydroxylating cinnamic acid to p-coumaric acid has been isolated from 10-day-oid cultures of Polyporus hispidus. The enzyme requires NADPH and FAD for maximum activity. Enzyme activity appears to be localized in the microsomal fraction with slight activity occurring in the mitochondrial fraction. The optimum pH for enzymatic activity is 7.5. This is the first report on any properties of this enzyme in a fungus. The enzyme differs from the known plant enzyme in its FAD requirement.

Leukaemia inhibitory factor stimulates proliferation of prospermatogonial stem cells

1997 ◽  
Vol 9 (7) ◽  
pp. 717 ◽  
Author(s):  
Diana B. Nikolova ◽  
Yordanka S. Martinova ◽  
Martin Seidensticker ◽  
Anthony R. Bellvé
Keyword(s):  
Stem Cells ◽  
Germ Cells ◽  
Proliferative Activity ◽  
Inhibitory Factor ◽  
Leukaemia Inhibitory Factor ◽  
Synthetic Activity ◽  
Local Regulation ◽  
Rat Testis ◽  
A Cell ◽  
Stimulation Of

The effect of leukaemia inhibitory factor (LIF) on the proliferation of prospermatogonial stem cells was testedin vitro. Pieces of 3-day-old rat testis were cultured in the presence of a range of doses of LIF alone or in combination with 1 ng mL -1 seminiferous growth factor (SGF). Stimulation of the proliferative activity of quiescent prospermatogonia was detected immunocytochemically with a cell proliferation kit. After 24 h culture, LIF signicantly increased the percentage of labelled prospermatogonia, with the peak of activity at 20 pg mL -1 . The combination of LIF and SGF resulted in a decrease in DNA synthetic activity of the germ cells. Hence, LIF and SGF play a role in local regulation at the onset of spermatogenesis in the rat testis.

Isolation of Antithrombin III from Normal and α1-Antitrypsin-Deficient Human Plasma

1977 ◽  
Vol 38 (02) ◽  
pp. 0475-0485 ◽  
Author(s):  
Anna D. Borsodi ◽  
Ralph A. Bradshaw
Keyword(s):  
Enzymatic Activity ◽  
Isoelectric Focusing ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Antithrombin Activity ◽  
Bovine Trypsin ◽  
Normal Plasma ◽  
Antitrypsin Deficiency ◽  
Simplified Procedure ◽  
Stimulation Of

SummaryThe plasma of individuals, hetero- or homozygous for α1-antitrypsin deficiency, contains greatly decreased amounts of antithrombin activity as assayed against factor Xa. However, heparin stimulation of the residual antithrombin activity is observed, which is comparable to that of normal plasma. Antithrombins isolated from both normal and α1-antitrypsin deficient plasma by a simplified procedure are indistinguishable in both properties and yields. The microheterogeneity observed on isoelectric focusing of both preparations can be eliminated by treatment with neuraminidase. Neither purified human antithrombin nor α1-antitrypsin, when assayed against bovine trypsin, is stimulated by heparin. These results clearly establish the unique natures of antithrombin and α1-antitrypsin and show that about 75% of the antithrombin activity measured in normal plasma is due to α1-antitrypsin. Estimates of anti thrombin III activity in normal plasma by assays dependent on enzymatic activity can probably be obtained only in the presence of heparin.

Stimulation of β-(l → 6)-glucanase production by oxidized pustulan

1972 ◽  
Vol 18 (10) ◽  
pp. 1543-1550 ◽  
Author(s):  
Robert G. Brown
Keyword(s):  
Enzyme Activity ◽  
Isoelectric Focusing ◽  
Gel Filtration ◽  
Tween 80 ◽  
Sole Source ◽  
Cellulase Production ◽  
Low Degree ◽  
Degree Of Oxidation ◽  
High Degree ◽  
Stimulation Of

A strain of Penicillium lilacinum, isolated from soil, produced pustulanase, β-(1 → 3)-glucanase, (EC. 3.2.1.6) and cellulase (EC.3.2.1.4) when cultivated on a medium containing pustulan as the sole source of carbon. If pustulan was replaced by ketopustulan, the production of pustulanase was stimulated about 10-fold although the amount of stimulation was dependent on the degree of oxidation of pustulan. β-(1 → 3)-Glucanase production was stimulated slightly by ketopustulan; however, the degree of oxidation did not affect significantly the yield of this enzyme. Cellulase production was either unaffected by the oxidized polymer, or at higher degrees of oxidation, decreased. Tween 80 stimulated the production of the three enzymes in media containing ketopustulan with a low degree of oxidation but was inhibitory to pustulanase and cellulase production in media containing ketopustulan with a high degree of oxidation. A combination of gel filtration and isoelectric focusing revealed that each enzyme activity was attributable to at least two proteins.

scholarly journals Purinergic stimulation of rat cardiomyocytes induces tyrosine phosphorylation and membrane association of phospholipase Cγ: a major mechanism for InsP3 generation

1996 ◽  
Vol 318 (2) ◽  
pp. 723-728 ◽  
Author(s):  
Michel PUCEAT ◽  
Guy VASSORT
Keyword(s):  
Tyrosine Kinase ◽  
Time Course ◽  
Kinase Inhibitor ◽  
Extracellular Atp ◽  
Rat Cardiomyocytes ◽  
Major Mechanism ◽  
Adult Rat ◽  
Hydrolysis Of ◽  
Purinergic Stimulation ◽  
Stimulation Of

Phospholipase Cγ (PLCγ) expression and activation by a purinergic agonist were investigated in adult rat cardiomyocytes. PLCγ is expressed in isolated cardiomyocytes. Stimulation of cells with extracellular ATP induces a rapid increase in membrane-associated PLCγ immunoreactivity most probably due to redistribution of the lipase from the cytosol to the membrane. The purine triggers a significant phosphorylation on tyrosine residues of a cytosolic pool of PLCγ with a time course that correlates with that of translocation. Extracellular ATP also increases intracellular Ins(1,4,5)P3 content. All these events (translocation and phosphorylation of PLCγ, InsP3 formation) are blocked by genistein, a tyrosine kinase inhibitor. The purinergic effect on both PLCγ translocation and phosphorylation are Ca-sensitive. We thus propose that the purinergic stimulation activates a non-receptor tyrosine kinase that phosphorylates PLCγ in the presence of an increased Ca level and induces PLCγ redistribution to the membrane. There, PLCγ becomes activated leading to the hydrolysis of phosphatidylinositol diphosphate and in turn Ins(1,4,5)P3 formation. This cascade of events may play a significant role in the induction of arrhythmogenesis by purinergic agonists.

Metabolic importance of Na+/K+-ATPase activity during sea urchin development.

1997 ◽  
Vol 200 (22) ◽  
pp. 2881-2892 ◽  
Author(s):  
P Leong ◽  
D Manahan
Keyword(s):  
Enzyme Activity ◽  
Atpase Activity ◽  
Sea Urchin ◽  
Sodium Pump ◽  
Sea Water ◽  
Strongylocentrotus Purpuratus ◽  
Lytechinus Pictus ◽  
Stimulation Of

Early stages of animal development have high mass-specific rates of metabolism. The biochemical processes that establish metabolic rate and how these processes change during development are not understood. In this study, changes in Na+/K+-ATPase activity (the sodium pump) and rate of oxygen consumption were measured during embryonic and early larval development for two species of sea urchin, Strongylocentrotus purpuratus and Lytechinus pictus. Total (in vitro) Na+/K+-ATPase activity increased during development and could potentially account for up to 77 % of larval oxygen consumption in Strongylocentrotus purpuratus (pluteus stage) and 80 % in Lytechinus pictus (prism stage). The critical issue was addressed of what percentage of total enzyme activity is physiologically active in living embryos and larvae and thus what percentage of metabolism is established by the activity of the sodium pump during development. Early developmental stages of sea urchins are ideal for understanding the in vivo metabolic importance of Na+/K+-ATPase because of their small size and high permeability to radioactive tracers (86Rb+) added to sea water. A comparison of total and in vivo Na+/K+-ATPase activities revealed that approximately half of the total activity was utilized in vivo. The remainder represented a functionally active reserve that was subject to regulation, as verified by stimulation of in vivo Na+/K+-ATPase activity in the presence of the ionophore monensin. In the presence of monensin, in vivo Na+/K+-ATPase activities in embryos of S. purpuratus increased to 94 % of the maximum enzyme activity measured in vitro. Stimulation of in vivo Na+/K+-ATPase activity was also observed in the presence of dissolved alanine, presumably due to the requirement to remove the additional intracellular Na+ that was cotransported with alanine from sea water. The metabolic cost of maintaining the ionic balance was found to be high, with this process alone accounting for 40 % of the metabolic rate of sea urchin larvae (based on the measured fraction of total Na+/K+-ATPase that is physiologically active in larvae of S. purpuratus). Ontogenetic changes in pump activity and environmentally induced regulation of reserve Na+/K+-ATPase activity are important factors that determine a major proportion of the metabolic costs of sea urchin development.

scholarly journals Effect of aluminium oxide nanoparticles on the enzymatic activity on microorganisms of activated sludge

2018 ◽  
Vol 44 ◽  
pp. 00033 ◽  
Author(s):  
Nina Doskocz ◽  
Katarzyna Affek ◽  
Monika Załęska-Radziwiłł
Keyword(s):  
Enzymatic Activity ◽  
Activated Sludge ◽  
Hydrolytic Enzymes ◽  
Aluminium Oxide ◽  
Cellular Respiration ◽  
Oxide Nanoparticles ◽  
Oxide Compound ◽  
Commercial Use ◽  
Aluminium Oxide Nanoparticles ◽  
Stimulation Of

The increased production and commercial use of nanoparticles (NPs), combined with a lack of regulation regarding their disposal, may result in the unwanted introduction of NPs to wastewater. Wastewater nutrient removal depends on the metabolisms of activated sludge bacteria and their related key enzymes. Therefore, the aim of this work was to determine the effect of aluminium oxide nanoparticles concentrations on the activated sludge enzymatic activity of microorganisms. Tested nanoparticles inhibition cellular respiration in TTC method in the four highest tested concentrations. Moreover, in most samples observed increase dehydrogenase activity. In this study, nano-Al2O3 also caused a clear stimulation of the activity of hydrolytic enzymes microorganisms of activate sludge. Effects of aluminum oxide (compound in bulk forms) on enzymatic activity were different than in the case of the nano from of Al2O3.

Convenient Partial Purification of Glucose Oxidase from Aspergillus niger A9 Fermentation Broth by Reversed Micelles

2012 ◽  
Vol 554-556 ◽  
pp. 957-961
Author(s):  
Hong An ◽  
Xi Feng He ◽  
Shu Gang Gao
Keyword(s):  
Enzyme Activity ◽  
Aspergillus Niger ◽  
Glucose Oxidase ◽  
Fermentation Broth ◽  
Volume Ratio ◽  
Reversed Micelles ◽  
Partial Purification ◽  
Ammonium Bromide ◽  
Ultrasonic Oscillation ◽  
Protein Activity

Aim of this work was to establish the optimum conditions for the extraction and recovery by cationic reversed micelles of glucose oxidase (GOX) from Aspergillus niger A9, The influence of pH, temperature, solvent/co-solvents ratio on the extraction was investigated by experiment, using the residual enzyme activity to evaluate the results. The best condition for GOX extraction were ensured using iso-octane as solvent and butanol and n-hexanol co-solvent at 76/18/6 volume ratio, pH 4.80, 200mM cetyl-trimethyl ammonium bromide (CTAB) as cationic surfactant, The enzyme activity of GOX is measured by DNS method (3,5-dinitro salicylic acid method). In the extraction process, ultrasonic oscillation was adopted to mix organic solvent and water, ultrasonic oscillation temperature is 45 °C. Protein activity recovery of GOX can reach 88.2% in extraction.

scholarly journals Induction of dopa (3,4-dihydroxyphenylalanine) decarboxylase in blowfly integument by ecdysone. A demonstration of synthesis of the enzyme de novo

1975 ◽  
Vol 146 (1) ◽  
pp. 121-126 ◽  
Author(s):  
E G Fragoulis ◽  
C E Sekeris
Keyword(s):  
Enzyme Activity ◽  
Steroid Hormones ◽  
De Novo ◽  
Steroid Hormone ◽  
Dopa Decarboxylase ◽  
Double Labelling ◽  
Labelling Technique ◽  
Immune Precipitation ◽  
Enzyme Molecules ◽  
Stimulation Of

The activity of the enzyme dopa (3,4-dihydroxyphenylalanine) decarboxylase, present in the epidermis cells of blowfly larvae, increases during the late third instar under the influence of the steroid hormone, ecdysone. By using the double-labelling technique and immune precipitation with univalent antibody to dopa decarboxylase, we demonstrated that the increase in enzyme activity was due to a stimulation of synthesis of enzyme molecules de novo. In this respect, the action of ecdysone is similar to the action of other steroid hormones.

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