scholarly journals Optimization of o-cresol degrading microorganism and kinetics of degradation

2018 ◽  
Vol 18 (4) ◽  
pp. 702
Author(s):  
Krishnan Nhattuketty Shainy ◽  
Rajamanickam Usha
Keyword(s):  
Substrate Concentration ◽  
Cell Mass ◽  
Serial Transfer ◽  
Initial Substrate ◽  
Pseudomonas Monteilii ◽  
Petroleum Contaminated Soil ◽  
Kinetics Of Degradation ◽  
High Concentrations ◽  
Mass Increase ◽  
Kinetics Of

In the present study, Pseudomonas monteilii CR13 isolated from petroleum contaminated soil demonstrated the highest specific o-cresol degradation rate at all tested o-cresol concentrations and also was not disturbed by the starting substrate concentration used (o-cresol-500 mg/L). After a serial transfer of the isolate into a series of increasing o-cresol level, the organism demonstrated significant improvement on degradation ability up to 3000 mg/L. The optimum condition for the cell mass increase and biodegradation of o-cresol by Pseudomonas monteilii was in the minimal mineral medium of 3 at a pH of 6.5 and temperature 30 °C, stirring velocity of 160 rpm, and the substrate concentration of 500 mg/L. The biodegradation kinetic study was carried out by bacteria in different initial substrate concentrations (500–3000 mg/L). In the present test the μmax, Ks and the μ were found 0.332 h-1, 0.166 mg/L and 0.0282 mg/L for 500 mg/L of o-cresol, respectively. The organism is highly promising and could be used to remove high concentrations of o-cresol from highly polluted aquatic and soil regions. The cells could be immobilized on a suitable matrix and the efficiency of degradation could be effectively improved.

scholarly journals The kinetics of slow-binding and slow, tight-binding inhibition: the effects of substrate depletion

1993 ◽  
Vol 294 (1) ◽  
pp. 195-200 ◽  
Author(s):  
S G Waley
Keyword(s):  
Substrate Concentration ◽  
Dissociation Constants ◽  
Tight Binding ◽  
Slow Step ◽  
First Order ◽  
Initial Substrate ◽  
Binding Inhibition ◽  
Kinetics Of ◽  
Nanomolar Range ◽  
Step Mechanism

Inhibitors with dissociation constants in the micromolar to nanomolar range are important, but hard to characterize kinetically, especially when the substrate concentration in the assay is less than Km. When inhibition increases during the course of the assay (slow-binding inhibition) the concentration of substrate may decrease appreciably. Methods that take substrate depletion into account are described for analysing experiments in which the initial substrate concentration is below Km. Fitting progress curves gives the rate constants for the second (slow) step in a two-step mechanism. An approximate value for the overall dissociation constant may be determined from measurements of rates when the reaction is treated as a first-order process. When the concentrations of inhibitor and enzyme are comparable numerical methods are required. Procedures, suitable for implementation on a microcomputer, for the solution of the differential equations and the fitting of progress curves are described.

scholarly journals Kinetics of photocatalytic removal of 2-amino-5-chloropyridine from water

2004 ◽  
pp. 79-86 ◽  
Author(s):  
Biljana Abramovic ◽  
Vesna Anderluh ◽  
Andjelka Topalov ◽  
Ferenc Gaal
Keyword(s):  
Titanium Dioxide ◽  
Kinetic Model ◽  
Substrate Concentration ◽  
Zero Order ◽  
Direct Photolysis ◽  
Pyridine Moiety ◽  
Initial Substrate ◽  
Photocatalytic Removal ◽  
Kinetics Of ◽  
Initial Substrate Concentration

Titanium dioxide sensitized photocatalytic degradation of a pyridine pesticide analogue, 2-amino-5-chloropyridine, was investigated by monitoring the pyridine moiety degradation, as well as by monitoring the chloride generated in the process. Effect of the initial substrate concentration on the rate of its degradation is reported. Here we show that the kinetics of both reactions are of the zero-order in the entire investigated concentration range. The Langmuir-Hinshelwood kinetic model successfully described the influence of the initial substrate concentration on the rate of the pyridine moiety degradation. It was found that dechlorination of the substrate takes place by direct photolysis. The differences in the kinetics of pyridine moiety degradation and dechlorination were explained on the basis of the electrostatic potential for the investigated compound.

scholarly journals Comparative Study of Chemical Stability of Two H1Antihistaminic Drugs, Terfenadine and ItsIn VivoMetabolite Fexofenadine, Using LC-UV Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Anna Gumieniczek ◽  
Anna Berecka-Rycerz ◽  
Rafał Pietraś ◽  
Izabela Kozak ◽  
Karolina Lejwoda ◽  
...  
Keyword(s):  
Comparative Study ◽  
Chemical Stability ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of Degradation ◽  
Effects Of Temperature ◽  
High Doses ◽  
Antihistaminic Drugs ◽  
Kinetics Of

A comparative study of chemical stability of terfenadine (TER) and itsin vivometabolite fexofenadine (FEX) was performed. Both TER and FEX were subjected to high temperature at different pH and UV/VIS light at different pH and then quantitatively analyzed using new validated LC-UV methods. These methods were used to monitor the degradation processes and to determine the kinetics of degradation for both the compounds. As far as the effects of temperature and pH were concerned, FEX occurred more sensitive to degradation than TER. As far as the effects of UV/VIS light and pH were concerned, the both drugs were similarly sensitive to high doses of light. Using all stress conditions, the processes of degradation of TER and FEX followed the first-order kinetics. The results obtained for these two antihistaminic drugs could be helpful in developing their new derivatives with higher activity and stability at the same time.

scholarly journals Desensitization Contributes to the Synaptic Response of Gain-of-Function Mutants of the Muscle Nicotinic Receptor

2006 ◽  
Vol 128 (5) ◽  
pp. 615-627 ◽  
Author(s):  
Sergio Elenes ◽  
Ying Ni ◽  
Gisela D. Cymes ◽  
Claudio Grosman
Keyword(s):  
Nicotinic Receptor ◽  
Dissociation Rate ◽  
Gain Of Function ◽  
Naturally Occurring ◽  
Channel Opening ◽  
Speed Up ◽  
High Concentrations ◽  
Dissociation Rate Constants ◽  
Kinetics Of ◽  
Peak Value

Although the muscle nicotinic receptor (AChR) desensitizes almost completely in the steady presence of high concentrations of acetylcholine (ACh), it is well established that AChRs do not accumulate in desensitized states under normal physiological conditions of neurotransmitter release and clearance. Quantitative considerations in the framework of plausible kinetic schemes, however, lead us to predict that mutations that speed up channel opening, slow down channel closure, and/or slow down the dissociation of neurotransmitter (i.e., gain-of-function mutations) increase the extent to which AChRs desensitize upon ACh removal. In this paper, we confirm this prediction by applying high-frequency trains of brief (∼1 ms) ACh pulses to outside-out membrane patches expressing either lab-engineered or naturally occurring (disease-causing) gain-of-function mutants. Entry into desensitization was evident in our experiments as a frequency-dependent depression in the peak value of succesive macroscopic current responses, in a manner that is remarkably consistent with the theoretical expectation. We conclude that the comparatively small depression of the macroscopic currents observed upon repetitive stimulation of the wild-type AChR is due, not to desensitization being exceedingly slow but, rather, to the particular balance between gating, entry into desensitization, and ACh dissociation rate constants. Disruption of this fine balance by, for example, mutations can lead to enhanced desensitization even if the kinetics of entry into, and recovery from, desensitization themselves are not affected. It follows that accounting for the (usually overlooked) desensitization phenomenon is essential for the correct interpretation of mutagenesis-driven structure–function relationships and for the understanding of pathological synaptic transmission at the vertebrate neuromuscular junction.

The Kinetics of Degradation of Chloramphenicol in Solution

1954 ◽  
Vol 43 (3) ◽  
pp. 129-134 ◽  
Author(s):  
Takeru Higuchi ◽  
Charles D. Bias ◽  
Arnold D. Marcus
Keyword(s):  
Kinetics Of Degradation ◽  
Kinetics Of

Analyzing the kinetics of degradation of Acid Red B dye through Fenton oxidation with online monitoring system

2021 ◽  
Vol 216 ◽  
pp. 412-422
Author(s):  
Aiguo Li ◽  
Xiaofeng Fang ◽  
Jiangyuan Sun ◽  
Qianpeng Liu ◽  
Yingying Lian ◽  
...  
Keyword(s):  
Monitoring System ◽  
Online Monitoring ◽  
Fenton Oxidation ◽  
Kinetics Of Degradation ◽  
Online Monitoring System ◽  
Kinetics Of

scholarly journals Evaluation of the kinetics of oxidation and removal of organic matter in the self-purification of a mountain river

DYNA ◽  
2015 ◽  
Vol 82 (191) ◽  
pp. 183-193 ◽  
Author(s):  
Jorge Virgilio Rivera Gutiérrez
Keyword(s):  
Water Quality ◽  
Water System ◽  
The Self ◽  
Organic Load ◽  
Mountain River ◽  
Kinetics Of Oxidation ◽  
Kinetic Rates ◽  
High Concentrations ◽  
Kinetics Of

The study is based on the determination of the kinetic rates and assessment of self-purification of the Frio River, due to the uptake of organic load. The kinetic rates were calculated by applying differential and logarithmic methods on concentrations of water quality determinants present in each of the (7) reach of the river. The water system easily recovers the amount of oxygen, k<sub>d</sub>= 0.4, k<sub>a</sub> 3.2 d<sup>-1</sup>, only receives 27.7 Ton. d<sup>-1</sup>, the organic load, making high concentrations of carbon, ammonium and remain sediment. The length Influence of discharges, LIV- BOD yielded a mean per tranche of 10 km, compared to 3 km each way, means that the river can´t self- purification that need more length of travel. The study illustrates the modeling of the determinants of quality, developed by the QUAL2K, using the calculated rates.

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