scholarly journals Evaluation of 3-Chlorobenzoate 1,2-Dioxygenase Inhibition by 2- and 4-Chlorobenzoate with a Cell-Based Technique

Biosensors ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 106 ◽  
Author(s):  
Emelyanova ◽  
Solyanikova
Keyword(s):  
Competitive Inhibition ◽  
Enzymatic Reaction ◽  
Oxygen Electrode ◽  
Electrochemical Reactor ◽  
Rhodococcus Opacus ◽  
Microbial Sensor ◽  
Rhodococcus Opacus 1Cp ◽  
Excess Substrate ◽  
A Cell ◽  
The Hill

The electrochemical reactor microbial sensor with the Clark oxygen electrode as the transducer was used for investigation of the competition between 3-chlorobenzoate (3-CBA) and its analogues, 2- and 4-chlorobenzoate (2-CBA and 4-CBA), for 3-chlorobenzoate-1,2-dioxygenase (3-CBDO) of Rhodococcus opacus 1CP cells. The change in respiration of freshly harvested R. opacus 1CP cells in response to 3-CBA served as an indicator of 3-CBDO activity. The results obtained confirmed inducibility of 3-CBDO. Sigmoidal dependency of the rate of the enzymatic reaction on the concentration of 3-CBA was obtained and positive kinetic cooperativity by a substrate was shown for 3-CBDO. The Hill concentration constant, S0.5, and the constant of catalytic activity, Vmax, were determined. Inhibition of the rate of enzymatic reaction by excess substrate, 3-CBA, was observed. Associative (competitive inhibition according to classic classification) and transient types of the 3-CBA-1,2-DO inhibition by 2-CBA and 4-CBA, respectively, were found. The kinetic parameters such as S0.5i and Vmaxi were also estimated for 2-CBA and 4-CBA. The disappearance of the S-shape of the curve of the V versus S dependence for 3-CBDO in the presence of 4-CBA was assumed to imply that 4-chlorobenzoate had no capability to be catalytically transformed by 3-chlorobenzoate-1,2-dioxygenase of Rhodococcus opacus 1CP cells.

scholarly journals Mitochondrial adenosine triphosphatase from human placenta--inhibition by free magnesium ions of ITP hydrolysis.

1994 ◽  
Vol 41 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Z Aleksandrowicz
Keyword(s):  
Competitive Inhibition ◽  
Competitive Inhibitor ◽  
Hill Coefficient ◽  
Negative Cooperativity ◽  
Magnesium Ions ◽  
Beef Liver ◽  
Bicarbonate Ions ◽  
The Hill ◽  
Kinetics Of ◽  
Free Magnesium

The effects of Mg2+ and bicarbonate on the kinetics of ITP hydrolysis by soluble ATPase (F1) from human placental mitochondria were studied. Increasing amounts of Mg2+ at fixed ITP concentration, caused a marked activation of F1 followed by inhibition at higher Mg2+ concentration. The appropriate substrate for the mitochondrial F1 seems to be the MgITP complex as almost no ITP was hydrolysed in the absence of magnesium. Mg2+ behaved as a competitive inhibitor towards the MgITP complex. In this respect the human placental enzyme differ from that from other sources such as yeast, beef liver or rat liver. The linearity of the plot presenting competitive inhibition by free Mg2+ of MgITP hydrolysis (in the presence of activating bicarbonate anion) suggests that both Mg2+ and MgITP bind to the same catalytic site (Km(MgITP) = 0.46 mM, Ki(Mg) = 4 mM). When bicarbonate was absent in the ITPase assay, placental F1 exhibited apparent negative cooperativity in the presence of 5 mM Mg2+, just as it did with MgATP as a substrate under similar conditions. Bicarbonate ions eliminated the negative cooperativity with respect to ITP (as the Hill coefficient of 0.46 was brought to approx. 1), and thus limited inhibition by free Mg2+. The results presented suggest that the concentration of free magnesium ions may be an important regulatory factor of the human placental F1 activity.

scholarly journals Delayed self-regulation and time-dependent chemical drive leads to novel states in epigenetic landscapes

2014 ◽  
Vol 11 (100) ◽  
pp. 20140706 ◽  
Author(s):  
Mithun K. Mitra ◽  
Paul R. Taylor ◽  
Chris J. Hutchison ◽  
T. C. B. McLeish ◽  
Buddhapriya Chakrabarti
Keyword(s):  
Single Gene ◽  
Self Regulation ◽  
Time Dependent ◽  
Sustained Oscillations ◽  
Regulatory Circuit ◽  
Oscillatory State ◽  
A Cell ◽  
The Hill ◽  
Stem Cell State

The epigenetic pathway of a cell as it differentiates from a stem cell state to a mature lineage-committed one has been historically understood in terms of Waddington's landscape, consisting of hills and valleys. The smooth top and valley-strewn bottom of the hill represent their undifferentiated and differentiated states, respectively. Although mathematical ideas rooted in nonlinear dynamics and bifurcation theory have been used to quantify this picture, the importance of time delays arising from multistep chemical reactions or cellular shape transformations have been ignored so far. We argue that this feature is crucial in understanding cell differentiation and explore the role of time delay in a model of a single-gene regulatory circuit. We show that the interplay of time-dependent drive and delay introduces a new regime where the system shows sustained oscillations between the two admissible steady states. We interpret these results in the light of recent perplexing experiments on inducing the pluripotent state in mouse somatic cells. We also comment on how such an oscillatory state can provide a framework for understanding more general feedback circuits in cell development.

Characterization of the Maleylacetate Reductase MacA of Rhodococcus opacus 1CP and Evidence for the Presence of an Isofunctional Enzyme

1998 ◽  
Vol 180 (14) ◽  
pp. 3503-3508 ◽  
Author(s):  
Volker Seibert ◽  
Elena M. Kourbatova ◽  
Ludmila A. Golovleva ◽  
Michael Schlömann
Keyword(s):  
Aromatic Compounds ◽  
Gene Clusters ◽  
Reductive Dehalogenation ◽  
Rhodococcus Opacus ◽  
Reductase Gene ◽  
Rhodococcus Opacus 1Cp ◽  
Dienelactone Hydrolase ◽  
Maleylacetate Reductase ◽  
Intradiol Dioxygenase

ABSTRACT Maleylacetate reductases (EC 1.3.1.32 ) have been shown to contribute not only to the bacterial catabolism of some usual aromatic compounds like quinol or resorcinol but also to the degradation of aromatic compounds carrying unusual substituents, such as halogen atoms or nitro groups. Genes coding for maleylacetate reductases so far have been analyzed mainly in chloroaromatic compound-utilizing proteobacteria, in which they were found to belong to specialized gene clusters for the turnover of chlorocatechols or 5-chlorohydroxyquinol. We have now cloned the gene macA, which codes for one of apparently (at least) two maleylacetate reductases in the gram-positive, chlorophenol-degrading strain Rhodococcus opacus 1CP. Sequencing of macA showed the gene product to be relatively distantly related to its proteobacterial counterparts (ca. 42 to 44% identical positions). Nevertheless, like the known enzymes from proteobacteria, the cloned Rhodococcusmaleylacetate reductase was able to convert 2-chloromaleylacetate, an intermediate in the degradation of dichloroaromatic compounds, relatively fast and with reductive dehalogenation to maleylacetate. Among the genes ca. 3 kb up- and downstream of macA, none was found to code for an intradiol dioxygenase, a cycloisomerase, or a dienelactone hydrolase. Instead, the only gene which is likely to be cotranscribed with macA encodes a protein of the short-chain dehydrogenase/reductase family. Thus, the R. opacus maleylacetate reductase genemacA clearly is not part of a specialized chlorocatechol gene cluster.

scholarly journals Site-Specific Cleavage of RNAs Derived from the PIM1 3′-UTR by a Metal-Free Artificial Ribonuclease

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 807 ◽  
Author(s):  
Felix Zellmann ◽  
Laura Thomas ◽  
Ute Scheffer ◽  
Roland Hartmann ◽  
Michael Göbel
Keyword(s):  
Competitive Inhibition ◽  
Reaction Rates ◽  
Phosphate Esters ◽  
Rna Cleavage ◽  
Site Specificity ◽  
Cleavage Rate ◽  
Short Oligonucleotide ◽  
A Cell ◽  
Artificial Nuclease ◽  
Oligonucleotide Conjugates

Oligonucleotide conjugates of tris(2-aminobenzimidazole) have been reported previously to cleave complementary RNA strands with high levels of sequence and site specificity. The RNA substrates used in these studies were oligonucleotides not longer than 29-mers. Here we show that ~150–400-mer model transcripts derived from the 3′-untranslated region of the PIM1 mRNA reacted with rates and specificities comparable to those of short oligonucleotide substrates. The replacement of DNA by DNA/LNA mixmers further increased the cleavage rate. Tris(2-aminobenzimidazoles) were designed to interact with phosphates and phosphate esters. A cell, however, contains large amounts of phosphorylated species that may cause competitive inhibition of RNA cleavage. It is thus important to note that no loss in reaction rates was observed in phosphate buffer. This opens the way to in-cell applications for this type of artificial nuclease. Furthermore, we disclose a new synthetic method giving access to tris(2-aminobenzimidazoles) in multigram amounts.

Identification and structural characterisation of novel trehalose dinocardiomycolates from n-alkane-grown Rhodococcus opacus 1CP

2005 ◽  
Vol 70 (5) ◽  
pp. 605-611 ◽  
Author(s):  
Susanne Niescher ◽  
Victor Wray ◽  
Siegmund Lang ◽  
Stefan R. Kaschabek ◽  
Michael Schlömann
Keyword(s):  
Rhodococcus Opacus ◽  
Structural Characterisation ◽  
Rhodococcus Opacus 1Cp

scholarly journals Catalytic and hydrodynamic properties of styrene monooxygenases from Rhodococcus opacus 1CP are modulated by cofactor binding

AMB Express ◽  
2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Anika Riedel ◽  
Thomas Heine ◽  
Adrie H Westphal ◽  
Catleen Conrad ◽  
Philipp Rathsack ◽  
...  
Keyword(s):  
Rhodococcus Opacus ◽  
Hydrodynamic Properties ◽  
Cofactor Binding ◽  
Rhodococcus Opacus 1Cp

Metabolism of 3-hydroxybenzoate and gentisate by strain Rhodococcus opacus 1CP

Microbiology ◽  
2012 ◽  
Vol 81 (3) ◽  
pp. 299-305 ◽  
Author(s):  
N. M. Subbotina ◽  
M. P. Kolomytseva ◽  
L. A. Golovleva
Keyword(s):  
Rhodococcus Opacus ◽  
Rhodococcus Opacus 1Cp

scholarly journals α-1-Anti-trypsin, an inhibitor of renin

1976 ◽  
Vol 153 (2) ◽  
pp. 505-507 ◽  
Author(s):  
S Scharpé ◽  
M Eid ◽  
W Cooreman ◽  
A Lauwers
Keyword(s):  
Human Plasma ◽  
Competitive Inhibition ◽  
Proteinase Inhibitors ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Renin Activity ◽  
Pig Kidney ◽  
Naturally Occurring ◽  
The Hill

A naturally occurring competitive inhibitor of pig kidney renin has been identified in human plasma. The inhibitor was shown to be α-1 anti-trypsin and the effect in vitro on the renin activity was examined. The slope in the Hill plot is compatible with the assumption of one-site competitive inhibition. Other proteinase inhibitors, such as α-2-macroglobulin and C1 inactivator, however, have no inhibitory effect on the renin-angiotensinogen reaction.

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