Enzymatic Activity and Photo-Kinetic Study of Cr(III), Mn(II), Co(II), Ni(II) and Cu(II) Complexes with Tetradentate

The Photo kinetic studies for five metal complexes of tetradentate Schiff base ligand were studied. These complexes were Chrome, Manganese, Cobalt, Nickle and Copper complexes. The kinetic values were achieved for the photoreaction and it referred to first order by in terms of complexes concentration. Three concentrations of these complexes to determined rate constant value which were determined by calculation the slope (-k) of relationship between radiation time on X-axis and natural logathirm of concentration changing on Y-axis. Values of rate constant were (0.0317min-1) for Cr-complex, (0.054min-1) for Mn-complex, (0.0706min-1) for Co-complex, (0.133min-1) for Ni-complex and (0.1211min-1) for Cu-complex. Relation between concentration on Y-axis and radiation time were showed the decreasing of concentration with time. Enzymatic study for the five complexes were achieved and showed that Cr-complex and Mn-complex showed competitive reactions and uncompetitive for Co-complex, Ni-complex and Cu-complex.

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Photocatalytic and Photoelectrocatalytic Degradation of Methyl Orange Using Graphite/PbTiO3 Composite

Indonesian Journal of Chemistry ◽

10.22146/ijc.21152 ◽

2018 ◽

Vol 16 (3) ◽

pp. 347

Author(s):

Candra Purnawan ◽

Sayekti Wahyuningsih ◽

Pramudita Putri Kusuma

Keyword(s):

Methyl Orange ◽

Rate Constant ◽

Order Reaction ◽

First Order Reaction ◽

Methyl Orange Degradation ◽

First Order ◽

Photoelectrocatalytic Degradation ◽

Methyl Orange Concentration ◽

Degradation Reaction ◽

Radiation Time

Synthesis of graphite/PbTiO3 composite as a catalyst in photodegradation and photoelectrodegradation process of methyl orange have been conducted. The purposes of this research are to study the effect of radiation time, composition of composite, voltage and pH of solution for methyl orange degradation. Photodegradation process of methyl orange was carried out for 5; 10; 15; 20; 25 and 30 min. Ratio of graphite : PbTiO3 (w/w) were varied at 1:3; 1:2; 1:1; 2:1 and 3:1. Meanwhile, the applied voltages were 7.5; 10 and 12.5 V and the photoelectrodegradation was conducted under pH condition of 3; 7; and 11, respectively. The result showed that optimum composition of graphite/PbTiO3 in the methyl orange photodegradation was obtained at 1:1 ratio for 30 min with degradation up to 90.43% ± 0.062. The degradation reaction follows first order reaction with a rate constant of 0.0688 min-1. The optimum voltage is 10 V, in which it reduced the methyl orange concentration up to 92.65% ± 0 with a rate constant 0.0941 min-1 for first order reaction. The optimum pH is pH = 11, that provide methyl orange reduction up to 95.28% ± 0.082.

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Kinetic studies of the reduction of neutrophil cytochrome b-558 by dithionite

Biochemical Journal ◽

10.1042/bj2370567 ◽

1986 ◽

Vol 237 (2) ◽

pp. 567-572 ◽

Cited By ~ 5

Author(s):

I Aviram ◽

M Sharabani

Keyword(s):

Cytochrome B ◽

Rate Constant ◽

Reaction Rate ◽

Kinetic Studies ◽

Order Rate Constant ◽

First Order ◽

Order Rate ◽

Ionic Detergent ◽

Activated Neutrophils ◽

Membrane Bound

The reduction with dithionite of neutrophil cytochrome b-558, implicated in superoxide generation by activated neutrophils, was investigated by a stopped-flow technique in non-ionic-detergent extracts of the membranes and in crude membrane particles. The dependence of the pseudo-first-order rate constants on the concentration of dithionite was consistent with a mechanism of reduction that involves the dithionite anion monomer SO2.- as the reactive species. The estimated second-order rate constant was 7.8 × 10(6) M-1 × S-1 for Lubrol PX-solubilized cytochrome b-558 and 5.1 × 10(6) M-1 × S-1 for the membrane-bound protein. The similarity of the kinetic constants suggests that solubilization did not introduce gross changes in the reactive site. Imidazole and p-chloromercuribenzoate, known as inhibitors of NADPH oxidase, did not affect significantly cytochrome b-558 reduction rates. The reaction rate of cytochrome b-558 with dithionite exhibited a near-zero activation energy. The first-order rate constant for reduction decreased with increasing ionic strength, indicating a positive effective charge on the reacting protein.

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The polymerization of ethylene on chromium oxide catalysts I. Kinetic studies

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1972.0117 ◽

1972 ◽

Vol 329 (1579) ◽

pp. 361-373 ◽

Cited By ~ 13

Keyword(s):

Rate Constant ◽

Initial Pressure ◽

Kinetic Studies ◽

Order Rate Constant ◽

Polymerization Reaction ◽

First Order ◽

Ethylene Pressure ◽

Order Rate ◽

Chromium Vi ◽

Chromium Oxide Catalysts

The rates of polymerization of ethylene on a supported chromium (VI) oxide Phillips catalysts have been measured. Catalysts were calcined in air at 460 °C and activated by pretreatment with ethylene at 300 °C. With increasing pretreatment times the activity of the catalyst increased to a maximum, after which over-reduction occurred and the activity fell. The products of the pretreatment process were water, carbon dioxide and a trace of butenes. Rates of polymerization were first order in ethylene pressure over the temperature range studied ( – 95 to 150 °C). The first order rate constant was sensitive to the initial pressure of ethylene added to the catalyst at the temperature at which the polymerization reaction was carried out. The results are explicable in terms of the production of active centres in the catalyst surface during contact with ethylene at 300 °C. Subsequent evacuation at 300 °C produced from some of these centres sites which had to be reactivated by adsorption of ethylene at low temperatures. The extent of re-activation increased with increasing ethylene pressure. The variation of first order rate constant with temperature showed a maximum at ca . – 23 °C and an apparent activation energy of 0.8 kJ mol -1 for the range –95 to – 23 °C. At temperatures above 227 °C the rate of polymerization was extremely slow.

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Development of Sustained Release Multi-Component Microparticulate System of Diclofenac Sodium and Tizanidine Hydrochloride

International Journal of Pharmaceutical Sciences and Nanotechnology ◽

10.37285/10.37285/ijpsn.2008.1.1.9 ◽

1970 ◽

Vol 1 (1) ◽

pp. 97-105

Author(s):

Kamlesh Dashora ◽

Shailendra Saraf ◽

Swarnalata Saraf

Keyword(s):

Particle Size ◽

Sustained Release ◽

Cellulose Acetate ◽

Rate Constant ◽

Diclofenac Sodium ◽

Order Rate Constant ◽

Anomalous Transport ◽

First Order ◽

Sem Study ◽

Transport Type

Sustained released tablets of diclofenac sodium (DIC) and tizanidine hydrochloride (TIZ) were prepared by using different proportions of cellulose acetate (CA) as the retardant material. Nine formulations of tablets having different proportion of microparticles developed by varied proportions of polymer: drug ratio ‘’i.e.’’; 1:9 -1:3 for DIC and 1:1 – 3:1 for TIZ. Each tablet contained equivalent to 100 mg of DIC and 6mg of TIZ. The prepared microparticles were white, free flowing and spherical in shape (SEM study), with the particle size varying from 78.8±1.94 to 103.33±1.28 µm and 175.92± 9.82 to 194.94±14.28µm for DIC and TIZ, respectively. The first order rate constant K1 of formulations were found to be in the range of K1 = 0.117-0.272 and 0.083- 0.189 %hr-1for DIC and TIZ, respectively. The value of exponent coefficient (n) was found to be in the range of 0.6328-0.9412 and 0.8589-1.1954 for DIC and TIZ respectively indicates anomalous to non anomalous transport type of diffusions among different formulations

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Kinetic Studies of [4n+2]π-Thermal Cyclodimerization of 1-(3-Pyridazinyl)-3-oxidopyridinium Betaines

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19921951 ◽

1992 ◽

Vol 57 (9) ◽

pp. 1951-1959 ◽

Cited By ~ 2

Author(s):

Madlene L. Iskander ◽

Samia A. El-Abbady ◽

Alyaa A. Shalaby ◽

Ahmed H. Moustafa

Keyword(s):

Energy Gap ◽

Activation Parameters ◽

Kinetic Studies ◽

Cyclic Transition ◽

Concerted Mechanism ◽

First Order ◽

Thermodynamic Activation Parameters ◽

Cyclic Transition State ◽

Complete Dissociation ◽

Homo Lumo

The reactivity of the base induced cyclodimerization of 1-(6-arylpyridazin-3-yl)-3-oxidopyridinium chlorides in a pericyclic process have been investigated kinetically at λ 380 nm. The reaction was found to be second order with respect to the liberated betaine and zero order with respect to the base. On the other hand dedimerization (monomer formation) was found to be first order. It was shown that dimerization is favoured at low temperature, whereas dedimerization process is favoured at relatively high temperature (ca 70 °C). Solvent effects on the reaction rate have been found to follow the order ethanol > chloroform ≈ 1,2-dichloroethane. Complete dissociation was accomplished only in 1,2-dichloroethane at ca 70 °C. The thermodynamic activation parameters have been calculated by a standard method. Thus, ∆G# has been found to be independent on substituents and solvents. The high negative values of ∆S# supports the cyclic transition state which is in favour with the concerted mechanism. MO calculations using SCF-PPP approximation method indicated low HOMO-LUMO energy gap of the investigated betaines.

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Determination of exothermic batch reactor specific model parameters

MATEC Web of Conferences ◽

10.1051/matecconf/201929201063 ◽

2019 ◽

Vol 292 ◽

pp. 01063

Author(s):

Lubomír Macků

Keyword(s):

Rate Constant ◽

Reaction Rate ◽

Batch Reactor ◽

Specific Model ◽

Reaction Rate Constant ◽

Order Reaction ◽

First Order Reaction ◽

Model Parameters ◽

Reactor Model ◽

First Order

An alternative method of determining exothermic reactor model parameters which include first order reaction rate constant is described in this paper. The method is based on known in reactor temperature development and is suitable for processes with changing quality of input substances. This method allows us to evaluate the reaction substances composition change and is also capable of the reaction rate constant (parameters of the Arrhenius equation) determination. Method can be used in exothermic batch or semi- batch reactors running processes based on the first order reaction. An example of such process is given here and the problem is shown on its mathematical model with the help of simulations.

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The reaction of μ-oxo-bis(phthalocyaninato)iron(III) with hydrogen sulphide in the presence of pyridine: Evidence for axial coordination of dichloromethane

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424605000265 ◽

2005 ◽

Vol 09 (03) ◽

pp. 198-205 ◽

Cited By ~ 1

Author(s):

Fabrizio Monacelli ◽

Elisa Viola

Keyword(s):

Reaction Mechanism ◽

Linear Function ◽

Rate Constant ◽

Hydrogen Sulphide ◽

Stoichiometric Ratio ◽

First Order ◽

Axial Coordination ◽

Elementary Sulphur ◽

Increasing Function ◽

Limiting Value

The oxo-bridged complex ( py ) FePc - O - FePc ( py ) ( py = pyridine , Pc = phthalocyaninato dianion) reacts in dichloromethane with hydrogen sulphide giving elementary sulphur and the reduced ( py )2( FePc ) complex in the stoichiometric ratio 1:1. Under excess py and H2S , the reaction is first-order and the rate constant at a given py concentration is an increasing function of the reducing agent concentration, with asymptotic tendency to a limiting value. This latter depends on the pyridine concentration being higher the lower is the base concentration. When the reaction is carried out in pure pyridine, the rate constant is, instead, a strictly linear function of [ H2S ], with zero intercept. A reaction mechanism is proposed where the dichloromethane is directly involved in the axial coordination about the iron centers and H2S competes efficiently with both pyridine and solvent.

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Horse liver alcohol dehydrogenase. A study of the essential lysine residue

Biochemical Journal ◽

10.1042/bj1490627 ◽

1975 ◽

Vol 149 (3) ◽

pp. 627-635 ◽

Cited By ~ 17

Author(s):

S S Chen ◽

P C Engel

Keyword(s):

Alcohol Dehydrogenase ◽

Rate Constant ◽

Lysine Residue ◽

Horse Liver Alcohol Dehydrogenase ◽

First Order ◽

Liver Alcohol Dehydrogenase ◽

Horse Liver ◽

Lysine Residues ◽

Modified Enzyme ◽

Covalent Complex

1. The inactivation of horse liver alcohol dehydrogenase by pyridoxal 5'-phosphate in phosphate buffer, pH8, at 10°C was investigated. Activity declines to a minimum value determined by the pyridoxal 5'-phosphate concentration. The maximum inactivation in a single treatment is 75%. This limit appears to be set by the ratio of the first-order rate constants for interconversion of inactive covalently modified enzyme and a readily dissociable non-covalent enzyme-modifier complex. 2. Reactivation was virtually complete on 150-fold dilution: first-order analysis yielded an estimate of the rate constant (0.164min-1), which was then used in the kinetic analysis of the forward inactivation reaction. This provided estimates for the rate constant for conversion of non-covalent complex into inactive enzyme (0.465 min-1) and the dissociation constant of the non-covalent complex (2.8 mM). From the two first-order constants, the minimum attainable activity in a single cycle of treatment may be calculated as 24.5%, very close to the observed value. 3. Successive cycles of modification followed by reduction with NaBH4 each decreased activity by the same fraction, so that three cycles with 3.6 mM-pyridoxal 5'-phosphate decreased specific activity to about 1% of the original value. The absorption spectrum of the enzyme thus treated indicated incorporation of 2-3 mol of pyridoxal 5'-phosphate per mol of subunit, covalently bonded to lysine residues. 4. NAD+ and NADH protected the enzyme completely against inactivation by pyridoxal 5'-phosphate, but ethanol and acetaldehyde were without effect. 5. Pyridoxal 5'-phosphate used as an inhibitor in steady-state experiments, rather than as an inactivator, was non-competitive with respect to both NADH and acetaldehyde. 6. The partially modified enzyme (74% inactive) showed unaltered apparent Km values for NAD+ and ethanol, indicating that modified enzyme is completely inactive, and that the residual activity is due to enzyme that has not been covalently modified. 7. Activation by methylation with formaldehyde was confirmed, but this treatment does not prevent subsequent inactivation with pyridoxal 5'-phosphate. Presumably different lysine residues are involved. 8. It is likely that the essential lysine residue modified by pyridoxal 5'-phosphate is involved either in binding the coenzymes or in the catalytic step. 9. Less detailed studies of yeast alcohol dehydrogenase suggest that this enzyme also possesses an essential lysine residue.

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Preparation, Solubility, Infrared Spectra and Radiolysis of Tetramethylammonium Hydrogenselenate Monohydrate and Lithium Tetramethylammonium Selenate Tetrahydrate

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20060411 ◽

2006 ◽

Vol 71 (3) ◽

pp. 411-422 ◽

Cited By ~ 2

Author(s):

David Havlíček ◽

Libor Turek ◽

Jiří Plocek ◽

Zdeněk Mička

Keyword(s):

Chemical Analysis ◽

Rate Constant ◽

Infrared Spectra ◽

Molecular Spectroscopy ◽

Anhydrous Salt ◽

First Order ◽

First Order Kinetics ◽

New Compounds

Solubility in the (Me4N)2SeO4-H2SeO4-H2O and (Me4N)2SeO4-Li2SeO4-H2O systems were studied. The new compounds, tetramethylammonium hydrogenselenate monohydrate ((Me4N)HSeO4·H2O) and lithium tetramethylammonium selenate tetrahydrate (Li(Me4N)SeO4·4H2O), have been found in these systems. Both substances were characterised by chemical analysis and IR molecular spectroscopy. Both of the title substances decompose under the influence of X-radiation and, thus, their structures cannot be determined. The radiolysis of both substances was studied in greater detail. Tetramethylammonium hydrogenselenate monohydrate is dehydrated by X-radiation to form the anhydrous salt. The reaction is controlled by first-order kinetics with a rate constant of 1.30(3) × 10-3 s-1.

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Spectrochemical Behavior of Carcinogenic Polycyclic Aromatic Hydrocarbons in Biological Systems. Part II: A Theoretical Rate Model for BaP Metabolism in Living Cells

Applied Spectroscopy ◽

10.1366/0003702963904782 ◽

1996 ◽

Vol 50 (11) ◽

pp. 1352-1359 ◽

Cited By ~ 8

Author(s):

Ping Chiang ◽

Kuang-Pang Li ◽

Tong-Ming Hseu

Keyword(s):

Rate Constant ◽

Living Cells ◽

Rate Model ◽

Number Density ◽

Order Process ◽

Irreversible Reaction ◽

First Order ◽

Metabolism Rate ◽

Polycyclic Aromatic ◽

Kinetics Of

An idealized model for the kinetics of benzo[ a]pyrene (BaP) metabolism is established. As observed from experimental results, the BaP transfer from microcrystals to the cell membrane is definitely a first-order process. The rate constant of this process is signified as k1. We describe the surface–midplane exchange as reversible and use rate constants k2 and k3 to describe the inward and outward diffusions, respectively. The metabolism is identified as an irreversible reaction with a rate constant k4. If k2 and k3 are assumed to be fast and not rate determining, the effect of the metabolism rate, k4, on the number density of BaP in the midplane of the microsomal membrane, m3, can be estimated. If the metabolism rate is faster than or comparable to the distribution rates, k2 and k3, the BaP concentration in the membrane midplane, m3, will quickly be dissipated. But if k4 is extremely small, m3 will reach a plateau. Under conditions when k2 and k3 also play significant roles in determining the overall rate, more complicated patterns of m3 are expected.

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