scholarly journals Kinetics of the reaction between oxygen and haemoglobin bound to haptoglobin (Short Communication)

1973 ◽  
Vol 133 (1) ◽  
pp. 205-207 ◽  
Author(s):  
Emilia Chiancone ◽  
Eraldo Antonini ◽  
Maurizio Brunori ◽  
Annette Alfsen ◽  
Françoise Lavialle
Keyword(s):  
Short Communication ◽  
Temperature Jump ◽  
Second Order ◽  
Stopped Flow ◽  
O2 Concentration ◽  
Kinetics Of

The kinetics of the reaction between O2 and haemoglobin bound to haptoglobin 1–1 were investigated by the stopped-flow and temperature-jump techniques. The reaction, which follows second-order kinetics in the lower concentration range, becomes independent of O2 concentration above about 150μm-O2.

scholarly journals Kinetics of Reduction of Fe(III) Complexes by Outer Membrane Cytochromes MtrC and OmcA of Shewanella oneidensis MR-1

2008 ◽  
Vol 74 (21) ◽  
pp. 6746-6755 ◽  
Author(s):  
Zheming Wang ◽  
Chongxuan Liu ◽  
Xuelin Wang ◽  
Matthew J. Marshall ◽  
John M. Zachara ◽  
...  
Keyword(s):  
Redox Potential ◽  
Outer Membrane ◽  
Kinetic Data ◽  
Shewanella Oneidensis ◽  
Reorganization Energy ◽  
Second Order ◽  
Metal Species ◽  
Stopped Flow ◽  
Kinetics Of ◽  
Kinetics Of Reduction

ABSTRACT Because of their cell surface locations, the outer membrane c-type cytochromes MtrC and OmcA of Shewanella oneidensis MR-1 have been suggested to be the terminal reductases for a range of redox-reactive metals that form poorly soluble solids or that do not readily cross the outer membrane. In this work, we determined the kinetics of reduction of a series of Fe(III) complexes with citrate, nitrilotriacetic acid (NTA), and EDTA by MtrC and OmcA using a stopped-flow technique in combination with theoretical computation methods. Stopped-flow kinetic data showed that the reaction proceeded in two stages, a fast stage that was completed in less than 1 s, followed by a second, relatively slower stage. For a given complex, electron transfer by MtrC was faster than that by OmcA. For a given cytochrome, the reaction was completed in the order Fe-EDTA > Fe-NTA > Fe-citrate. The kinetic data could be modeled by two parallel second-order bimolecular redox reactions with second-order rate constants ranging from 0.872 μM−1 s−1 for the reaction between MtrC and the Fe-EDTA complex to 0.012 μM−1 s−1 for the reaction between OmcA and Fe-citrate. The biphasic reaction kinetics was attributed to redox potential differences among the heme groups or redox site heterogeneity within the cytochromes. The results of redox potential and reorganization energy calculations showed that the reaction rate was influenced mostly by the relatively large reorganization energy. The results demonstrate that ligand complexation plays an important role in microbial dissimilatory reduction and mineral transformation of iron, as well as other redox-sensitive metal species in nature.

Etude cinétique des systèmes Cu(II)•Adénosine et Cu(II)•D-Ribose

1972 ◽  
Vol 50 (19) ◽  
pp. 3117-3123 ◽  
Author(s):  
G. Boivin ◽  
M. Zador
Keyword(s):  
Kinetic Parameters ◽  
Acidic Medium ◽  
Temperature Jump ◽  
Strong Acid ◽  
Basic Medium ◽  
Stopped Flow ◽  
Acid Solutions ◽  
Flow Method ◽  
Kinetics Of ◽  
Adenine Base

The kinetics of the formation and dissociation of Cu(II) complexes of adenosine have been determined in acidic and basic medium. In acidic medium, the complex is formed between the Cu(II) and the adenine base and the kinetic parameters have been obtained in this case using a temperature jump method. In basic medium, only the dissociation of the complexes could be studied by a stopped-flow method, by addition of EDTA or strong acid solutions. In these complexes, Cu(II) is bridged with ribose hydroxyls. Finally, D-ribose has also been studied for comparison in the same conditions. The mechanism of these reactions is discussed.

Absolute Light Scattering Calibration of the Stopped-Flow Spectrophotometer with Application to the Kinetics of Formation of Monodispersed Colloidal Hematite

1987 ◽  
Vol 41 (3) ◽  
pp. 402-407 ◽  
Author(s):  
Wan Peter Hsu ◽  
Ramesh C. Patel ◽  
Egon Matijevic
Keyword(s):  
Colloidal Silica ◽  
Temperature Jump ◽  
Scattered Light ◽  
Calibration Method ◽  
Stopped Flow ◽  
Flow Temperature ◽  
Hydrous Oxides ◽  
Solid Iron ◽  
Kinetics Of Formation ◽  
Kinetics Of

A calibration method based on absolute intensities of scattered light from colloidal silica was developed to standardize the stopped-flow temperature jump spectrophotometer (SFTJ). The need for such calibration was exemplified by the study of the temperature effect on the Rayleigh ratio changes during the formation of solid iron (hydrous) oxides.

scholarly journals Stopped-flow kinetics of oxygen uptake and release by embryonic red blood cells

1989 ◽  
Vol 261 (3) ◽  
pp. 1009-1013 ◽  
Author(s):  
T Brittain ◽  
R Simpson
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Stopped Flow ◽  
Embryonic Cells ◽  
O2 Uptake ◽  
O2 Concentration ◽  
Time Courses ◽  
Early Mouse ◽  
Kinetics Of ◽  
Uptake And Release

The processes of O2 uptake and release by the three embryonic haemoglobins contained within early mouse embryonic red blood cells have been studied using dual-wavelength stopped-flow kinetic spectroscopy. The rate of O2 uptake in the pseudo-spherical, nucleated, embryonic red blood cells exhibits a greater than first-order dependence on O2 concentration. The time courses for the release from the red blood cells into dithionite-containing solutions tends towards a limiting rate at high dithionite concentrations. The rates of both the uptake and release processes observed in the embryonic cells are compared with those previously seen for adult mouse red blood cells. A new mathematical model is described which accurately simulates both uptake and release experimental data for the nucleated embryonic red blood cells.

Kinetics of the Reaction of Nickel(II) and 2,2′-Bipyridine in Ethanol

1973 ◽  
Vol 51 (23) ◽  
pp. 3975-3977 ◽  
Author(s):  
M. L. Sanduja ◽  
W. MacF. Smith
Keyword(s):  
Kinetic Parameters ◽  
Rate Constant ◽  
Order Rate Constant ◽  
Second Order ◽  
Stopped Flow ◽  
Ligand Specificity ◽  
Temperature Range ◽  
Kinetics Of Formation ◽  
The Difference ◽  
Kinetics Of

The kinetics of formation of the monobipyridine complex of nickel(II) in ethanol has been studied with stopped-flow methods over the temperature range 7 to 35 °C. The value of the second order rate constant kf at 25 °C of 6.6 × 10−3M−1 s1 and the values of ΔH≠ (10.1 ± 1.0 kcal mol−1) and of ΔS≠ (−7.3 ± 3.4 cal deg−1 mol−1) are close to the corresponding values for ethanol exchange on nickel(II) and suggest that the mechanism is dissociative interchange. However the difference in the values of the kinetic parameters of this reaction and those previously reported for the reactions involving the chemically similar phenanthroline imply a degree of ligand specificity for the reactions in ethanol which is considerably larger than is the case for reactions in water and methanol and that a common Id mechanism with monodentate formation being rate controlling is not applicable to both reactions.

Kinetics of the reaction between hexamethylenediisocyanate and 1-pentanol

1983 ◽  
Vol 48 (11) ◽  
pp. 3279-3286
Author(s):  
Slavko Hudeček ◽  
Miloslav Bohdanecký ◽  
Ivana Hudečková ◽  
Pavel Špaček ◽  
Pavel Čefelín
Keyword(s):  
Liquid Chromatography ◽  
Rate Constants ◽  
Reversed Phase ◽  
Order Reaction ◽  
Second Order ◽  
Second Order Reaction ◽  
Reversed Phase Liquid Chromatography ◽  
Consecutive Reactions ◽  
Phase Liquid ◽  
Kinetics Of

The reaction between hexamethylenediisocyanate and 1-pentanol in toluene was studied by means of reversed-phase liquid chromatography. By employing this method, it was possible to determine all components of the reaction mixture including both products, i.e. N-(6-isocyanate hexyl)pentylcarbamate and N,N'-bis(pentyloxycarbonyl)hexamethylenediamine. Relations for the calculation of kinetic constants were derived assuming a competitive consecutive second-order reaction. It was demonstrated that the reaction involved in this case is indeed a second-order reaction, and the rate constants of the first and second consecutive reactions were determined.

Evidence for general base catalysis by protic solvents in a kinetic study of alcoholyses and hydrolyses of 1-(phenoxycarbonyl)pyridinium ions under both solvolytic and non-solvolytic conditions

2009 ◽  
Vol 74 (1) ◽  
pp. 43-55 ◽  
Author(s):  
Dennis N. Kevill ◽  
Byoung-Chun Park ◽  
Jin Burm Kyong
Keyword(s):  
Second Order ◽  
Base Catalysis ◽  
Substitution Reactions ◽  
Third Order ◽  
Methoxy Derivative ◽  
First Order ◽  
General Base ◽  
Protic Solvents ◽  
Kinetics Of ◽  
Pyridinium Ions

The kinetics of nucleophilic substitution reactions of 1-(phenoxycarbonyl)pyridinium ions, prepared with the essentially non-nucleophilic/non-basic fluoroborate as the counterion, have been studied using up to 1.60 M methanol in acetonitrile as solvent and under solvolytic conditions in 2,2,2-trifluoroethan-1-ol (TFE) and its mixtures with water. Under the non- solvolytic conditions, the parent and three pyridine-ring-substituted derivatives were studied. Both second-order (first-order in methanol) and third-order (second-order in methanol) kinetic contributions were observed. In the solvolysis studies, since solvent ionizing power values were almost constant over the range of aqueous TFE studied, a Grunwald–Winstein equation treatment of the specific rates of solvolysis for the parent and the 4-methoxy derivative could be carried out in terms of variations in solvent nucleophilicity, and an appreciable sensitivity to changes in solvent nucleophilicity was found.

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