LYTIC ENZYMES OF SORANGIUM SP.: ISOLATION AND ENZYMATIC PROPERTIES OF THE α- AND β-LYTIC PROTEASES

1965 ◽  
Vol 43 (12) ◽  
pp. 1935-1954 ◽  
Author(s):  
D. R. Whitaker
Keyword(s):  
Substantial Part ◽  
Arthrobacter Globiformis ◽  
Lytic Enzymes ◽  
Trace Impurities ◽  
Citrate Buffer ◽  
Egg White Lysozyme ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Low Concentrations ◽  
Hydrolyze Casein

Procedures are described for the isolation of two lytic enzymes from culture filtrates of a species of Sorangium. The enzymes, designated α-lytic protease and β-lytic protease, are responsible for most of the filtrate's lytic activity towards Arthrobacter globiformis cells. The enzymes were adsorbed from the filtrate by Amberlite CG50, separated by displacement from the resin with citrate buffer containing a gradient of sodium citrate concentration, and refractionated on columns of the same resin. Trace impurities in the β-enzyme were removed by precipitation of the enzyme with ammonium sulfate. The β-enzyme has been crystallized.On electrophoresis in Tris buffer of pH 8.0, the α-enzyme migrates slightly faster than egg-white lysozyme, the β-enzyme slightly slower. The absorptivity of the α-enzyme at 280 mμ was estimated to be 0.89; that of the β-enzyme 2.05.Low concentrations of the β-enzyme lyse suspensions of Arthrobacter globiformis cells completely, and moderately higher concentrations lyse suspensions of Micrococcus lysodeikticus cells completely; corresponding concentrations of the α-enzyme lyse the suspensions incompletely. The concomitant changes in A660 of the suspensions are consistent with zero-order kinetics for the β-enzyme and first-order kinetics for the α-enzyme. Untreated and partially lysed suspensions of Arthrobacter cells show little difference in the dependence of their absorbances on wavelength; corresponding suspensions of Micrococcus cells show marked differences in this respect, and the nature of the change suggests that the breakup of clumps of cells is responsible for a substantial part of the change in absorbance measured during lysis of suspensions of Micrococcus cells. Phase-contrast photomicrographs of cells undergoing lysis show that individual cells vary greatly in their rates of lysis; swelling and decreases in the refractive index precede fragmentation of the cell and may contribute appreciably to the change in absorbance of the suspension.Both enzymes hydrolyze casein. The α-enzyme has the greater activity towards this substrate.

scholarly journals The Kinetics of Clearance from the Circulation of Man of Heparin and a Semi-Synthetic Heparin Analogue

1977 ◽  
Author(s):  
D. A. Lane ◽  
R. Michalski ◽  
V. V. Kakkar
Keyword(s):  
High Specificity ◽  
Antithrombotic Agent ◽  
First Order ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Low Concentrations ◽  
Equal Dose ◽  
Rapid Clearance ◽  
The Difference ◽  
High Concentrations

A study has been made of a low molecular weight semi-synthetic heparin analogue, (SSHA) that may be clinically useful as an antithrombotic agent because of itsreported high specificity for potentiating antithrombin III activity. The clearance from the circulation of both heparin and the analogue has been studied in man following intravenous injection. Heparin obeyed almost zero order kinetics when assayed using a specific anti-Xa assay and first order kinetics when measured with KCCT. At high concentrations the heparin analogue was cleared with first order kinetics when assayed both with the anti-Xa assay and with KCCT. At low concentrations the analogue produced between one half and two-thirds of the anti-Xa activity of an equal dose of heparin, producing only a small prolongation of KCCT. With increasing dose, the more specific anti-Xa potentiating effect of SSHA decreased in part because of the difference in kinetic behaviour between heparin and SSHAbut largely because of a flattening of its anti-Xa dose response curve. Because of the initial more rapid clearance of higher doses of heparin from plasma when it is measured by the KCCT, these results suggest that the use of KCCT can cause a small underestimate of circulating heparin anti-thrombotic activity.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

scholarly journals Stress Degradation Studies and Kinetic Determinations of Duloxetine Enteric-Coated Pellets by HPLC

2010 ◽  
Vol 93 (6) ◽  
pp. 1829-1835 ◽  
Author(s):  
Patrícia Gomes ◽  
Nathalie R Wingert ◽  
Clésio S Paim ◽  
Elfrides E S Schapoval ◽  
Martin Steppe
Keyword(s):  
Degradation Products ◽  
Potassium Phosphate ◽  
Assay Method ◽  
Pharmaceutical Dosage Form ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Stress Degradation ◽  
Enteric Coated ◽  
Uv C

Abstract A stability-indicating HPLC assay method was developed for the quantitative determination of duloxetine (DLX) in a pharmaceutical dosage form in the presence of its degradation products, and kinetic determinations were evaluated in acid conditions and UV-C radiation exposure. Chromatographic separation was achieved by use of an ACE<sup/> C18 column (250 4.0 mm id, 5 m particle size). The mobile phase was prepared by mixing aqueous 50 mM potassium phosphate buffer (pH 6.0 containing 0.3 triethylamine) and acetonitrile (60 40, v/v). DLX was rapidly degraded in an acid medium and in the presence of hydrogen peroxide and UV-C radiation; it was more stable in alkaline medium. The described method was linear over a range of 4.014.0 g/mL for determination of DLX (r = 0.9998). The precision was demonstrated by the RSD of intraday (0.791.07) and interday (0.85) studies. The mean recovery was found to be 100.56. The acid degradation of DLX in 0.1 M HCl solution showed an apparent zero-order kinetics (k = 0.177 g/mL/min), and the photodegradation demonstrated an apparent first-order kinetics (k = 0.082 g/mL/min). The developed method was found to be simple, specific, robust, linear, precise, and accurate for the determination of DLX in enteric-coated pellets.

scholarly journals Iron-transport characteristics of vesicles of brush-border and basolateral plasma membrane from the rat enterocyte

1977 ◽  
Vol 164 (2) ◽  
pp. 289-294 ◽  
Author(s):  
E J Eastham ◽  
J I Bell ◽  
A P Douglas
Keyword(s):  
Small Intestine ◽  
Plasma Membrane ◽  
Brush Border ◽  
Membrane Vesicles ◽  
Enzyme Assays ◽  
Facilitated Diffusion ◽  
First Order ◽  
First Order Kinetics ◽  
Low Concentrations ◽  
Basolateral Plasma Membrane

Vesicles of brush-border and basolateral plasma membrane were prepared from enterocytes of the rat small intestine. The separateness of these two varieties of plasma membrane was confirmed by appropriate enzyme assays. The uptake of Fe2+ by these membrane vesicles was studied, and the results suggest differences between the two types of membrane in both the amount of Fe2+ taken up and in the rate of uptake. At low (up to 3 micrometer) concentrations of Fe2+, uptake by both membrane types showed evidence of saturation and could be blocked with the thiol inactivator N-ethylmaleimide. The studies suggest that Fe2+ is taken into an osmotically active space by a process of facilitated diffusion at low concentrations, but that at higher concentrations the process appeared to obey first-order kinetics. The data provide further evidence for the existence of functional polarity in the epithelial cell of the small intestine.

scholarly journals Thermal and photo-stability of the antioxidant potential of Spirulina platensis powder

2016 ◽  
Vol 77 (2) ◽  
pp. 332-339 ◽  
Author(s):  
L. M. Colla ◽  
C. D. Bertol ◽  
D. J. Ferreira ◽  
J. Bavaresco ◽  
J. A. V. Costa ◽  
...  
Keyword(s):  
Spirulina Platensis ◽  
Storage Conditions ◽  
Antioxidant Potential ◽  
Photo Degradation ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Lipid System ◽  
Fluorescence Light ◽  
Photo Stability ◽  
Kinetics Of

Abstract This work aimed to evaluate the thermal and photo stability of the antioxidant potential (AP) of the Spirulina platensis biomass. Thermal stability was established at 25ºC, 40ºC and 50ºC for 60 days, in the dark, protected from light. Photo stability was evaluated using UV (15 W, λ = 265 nm) and fluorescent (20 W, 0.16 A, power factor FP > 0.5, 50/60 Hz, 60 lm/w, 1200 lm) light for 90 days in capsules, glass and Petri dishes, at room temperature. The AP of the biomass in these conditions was determined at intervals (every 7 and 30 days in the studies of thermal and photo stability, respectively) using the induction of the oxidation of a lipid system by heat and aeration. In this lipid system, the biomass submitted to degradation was used as an antioxidant. The kinetics of the reaction was determined by the Arrhenius method. Thermal degradation was found to follow zero order kinetics, whereas photo degradation followed first order kinetics. The AP decreased 50% after 50 days at 25°C. At 40°C and 50°C, the AP decreased more than 50% after 35 and 21 days of exposition, respectively. The decrease of the AP of Spirulina was more sensible to UV and fluorescence light. After 30 days of exposition, the AP decreased more than 50% in all storage conditions tested. The antioxidant potential of Spirulina platensis is easily degraded when the biomass is exposed to heat and light, indicating the need for care to be taken in its storage.

Parameters Effect on Photocatalytic Reduction Kinetics of Bromate in Aqueous Dispersion of TiO2

2013 ◽  
Vol 779-780 ◽  
pp. 1658-1665
Author(s):  
Rong Shu Zhu ◽  
Fei Tian ◽  
Ling Ling Zhang ◽  
Ling Min Yu
Keyword(s):  
Aqueous Dispersion ◽  
Zero Order ◽  
Photocatalytic Reduction ◽  
Reduction Kinetics ◽  
First Order ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Experimental Parameters ◽  
Pseudo First Order ◽  
Kinetics Of

This paper studied the photocatalytic reduction kinetics of bromate in aqueous dispersion of TiO2 and investigated the effects of experimental parameters, including initial concentration of BrO3-, pH, TiO2 dosage, anion and cation. The results indicate that the process of photocatalytic reduction of bromate follows a zero-order kinetics. In all the investigated experimental parameters, the initial bromate concentration, pH and anion have great effect on the photocatalytic reduction kinetics. The processes of photocatalytic reduction of bromate show the pseudo first-order kinetics at initial bromate concentration of 0.39 μmolL-1, pH=5.0, or in presence of HCO3-/CO32-, NO3-, SO42-, respectively.

scholarly journals Evaluation of Kinetic Pseudo-Order in the Photocatalytic Degradation of Ofloxacin

Catalysts ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 24
Author(s):  
Giora Rytwo ◽  
Arye Lev Zelkind
Keyword(s):  
Half Life ◽  
Advanced Oxidation Processes ◽  
Degradation Kinetics ◽  
Simple Procedure ◽  
Life Time ◽  
Zero Order Kinetics ◽  
Low Concentrations ◽  
Antibiotic Drug ◽  
Kinetics Of ◽  
Additional Reduction

Ofloxacin is a highly efficient and widely used antibiotic drug. It is classified as a refractory pollutant due to its poor biodegradability. Consequently, it is commonly found in water sources, requiring efficient methods for its removal. Advanced oxidation processes (AOPs) offer efficient alternatives since those yield complete degradation not achieved in adsorption or membrane processes. Previous studies suggest ofloxacin degradation follows a pseudo-first or -second order processes, whereas for full removal of refractory pollutants—lower pseudo-orders are required. Monitoring the actual “pseudo-order” degradation kinetics of ofloxacin is needed to evaluate any proposed AOP process. This study presents a simple procedure to evaluate pseudo-orders of AOPs. Photolysis of 20 μM ofloxacin solutions follow pseudo-zero order kinetics, with half-life times (t1/2) of approx. 60 min. TiO2 heterogenous catalysts have been shown to have no influence at low concentrations (0.2 mg L−1), but a significant reduction of half-life time (t1/2 = 20 min) and increase in pseudo-order (0.8) is measured at 2.0 mg L−1. Similar results are obtained with homogenous catalysis by 2.0 mg L−1 H2O2. The combination of H2O2 and TiO2 catalysts shows additional reduction in half-time life with increase in the pseudo-order to 1.2. The conclusions are (1) heterogenous and homogenous photocatalysis can effectively degrade ofloxacin, (2) combined photocatalysis yields higher pseudo-order, being less prone to achieve full removal, and (3) analysis of specific pseudo-orders in AOPs of refractory pollutants helps to further elucidate the efficiency of the processes.

Inactivation of Toluene 2-Monooxygenase in Burkholderia cepacia G4 by Alkynes

1999 ◽  
Vol 65 (2) ◽  
pp. 632-639 ◽  
Author(s):  
Chris M. Yeager ◽  
Peter J. Bottomley ◽  
Daniel J. Arp ◽  
Michael R. Hyman
Keyword(s):  
Gas Phase ◽  
Burkholderia Cepacia ◽  
Dependent Manner ◽  
Inhibitory Effects ◽  
Specific Mechanism ◽  
Monooxygenase Activity ◽  
First Order Kinetics ◽  
Low Concentrations ◽  
High Concentrations ◽  
Dependent Growth

ABSTRACT High concentrations of acetylene (10 to 50% [vol/vol] gas phase) were required to inhibit the growth of Burkholderia cepaciaG4 on toluene, while 1% (vol/vol) (gas phase) propyne or 1-butyne completely inhibited growth. Low concentrations of longer-chain alkynes (C5 to C10) were also effective inhibitors of toluene-dependent growth, and 2- and 3-alkynes were more potent inhibitors than their 1-alkyne counterparts. Exposure of toluene-grownB. cepacia G4 to alkynes resulted in the irreversible loss of toluene- and o-cresol-dependent O2 uptake activities, while acetate- and 3-methylcatechol-dependent O2 uptake activities were unaffected. Toluene-dependent O2 uptake decreased upon the addition of 1-butyne in a concentration- and time-dependent manner. The loss of activity followed first-order kinetics, with apparent rate constants ranging from 0.25 min−1 to 2.45 min−1. Increasing concentrations of toluene afforded protection from the inhibitory effects of 1-butyne. Furthermore, oxygen, supplied as H2O2, was required for inhibition by 1-butyne. These results suggest that alkynes are specific, mechanism-based inactivators of toluene 2-monooxygenase inB. cepacia G4, although the simplest alkyne, acetylene, was relatively ineffective compared to longer alkynes. Alkene analogs of acetylene and propyne—ethylene and propylene—were not inactivators of toluene 2-monooxygenase activity in B. cepacia G4 but were oxidized to their respective epoxides, with apparentKs and V max values of 39.7 μM and 112.3 nmol min−1 mg of protein−1 for ethylene and 32.3 μM and 89.2 nmol min−1 mg of protein−1 for propylene.

Use of purified lyophilized human lactate dehydrogenase isoenzymes in a study of the measurement of lactate dehydrogenase activity.

1986 ◽  
Vol 32 (5) ◽  
pp. 758-762 ◽  
Author(s):  
D A Smith ◽  
G C Moses ◽  
A R Henderson
Keyword(s):  
Lactate Dehydrogenase ◽  
Zero Order ◽  
Lactate Dehydrogenase Activity ◽  
First Order ◽  
First Order Kinetics ◽  
Activity Concentrations ◽  
Zero Order Kinetics ◽  
Specific Activities ◽  
The Stability ◽  
Lactate Dehydrogenase Isoenzymes

Abstract We examined the stability of human lactate dehydrogenase (EC 1.1.1.27; LD) isoenzymes 1, 2, and 3--purified to specific activities of about 200 kU/g--when lyophilized in a buffered stabilized matrix of bovine albumin. Each isoenzyme was prepared at two activity concentrations and stored at -20, 4, 20, 37, and 56 degrees C for as long as six months. LD-1 activity decayed with zero-order kinetics, LD-2 and LD-3 with first-order kinetics. The extrapolated half-lives of these preparations at -20 degrees C varied between 80 and 530 years. Stability of reconstituted samples stored at 4 degrees C was excellent for LD-1 but poor for LD-2 and LD-3. We suggest that preparations of human LD-1 be further investigated as a possible reference material.

Investigations into the kinetics and stoichiometry of bacterial oxidation of covellite (CuS) using a polarographic oxygen probe

1978 ◽  
Vol 24 (8) ◽  
pp. 998-1003 ◽  
Author(s):  
Pamela A. D. Rickard ◽  
Donald G. Vanselow
Keyword(s):  
Oxygen Uptake Rate ◽  
Zero Order ◽  
Bacterial Oxidation ◽  
Kinetics Of Oxidation ◽  
First Order ◽  
Cupric Ion ◽  
First Order Kinetics ◽  
Zero Order Kinetics ◽  
Cupric Sulphate ◽  
Kinetics Of

"Oxygraph" apparatus was used to measure quantitatively the kinetics of oxidation of synthetic covellite (CuS) in the presence and absence of Thiobacillus species. The expected stoichiometric relationship between oxygen consumed and cupric sulphate produced was verified by atomic absorption assays of cupric ion and sulphate ion. Thiobacillus cultures markedly increased the oxidation rate.The dependence of each oxygen-uptake rate on oxygen concentration was also measured. Sterile controls and some bacterial cultures showed first-order kinetics while other cultures showed zero-order kinetics.Addition of biological inhibitors to reacting slurries revealed that cultures showing first-order kinetics did not oxidize CuS itself but merely oxidized elemental sulphur formed by non-enzymic oxidation of CuS. Cultures showing zero-order kinetics oxidized CuS in a way that resulted in all oxygen reduction being enzymic. This mechanism possibly involves the cyclic oxidation and reduction of soluble iron.

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