scholarly journals The effect of quaternary structure on the kinetics of conformational changes and nanosecond geminate rebinding of carbon monoxide to hemoglobin.

1988 ◽  
Vol 85 (7) ◽  
pp. 2151-2155 ◽  
Author(s):  
L. P. Murray ◽  
J. Hofrichter ◽  
E. R. Henry ◽  
M. Ikeda-Saito ◽  
K. Kitagishi ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Conformational Changes ◽  
Quaternary Structure ◽  
Kinetics Of

scholarly journals Effect of pH on the Hydrolytic Kinetics of Gamma-Glutamyl Transferase fromBacillus subtilis

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sharath Balakrishna ◽  
Asmita Prabhune
Keyword(s):  
Conformational Changes ◽  
Quaternary Structure ◽  
Gamma Glutamyl Transferase ◽  
Effect Of Ph ◽  
Gamma Glutamyl ◽  
Steady State Kinetics ◽  
Kinetic Transformation ◽  
Ph Range ◽  
Glutamyl Transferase ◽  
Kinetics Of

The effect of pH on the steady state kinetics of gamma-glutamyl transferase (GGT) fromBacillus subtiliswas examined using glutamyl-(3-carboxyl)-4-nitroanilide as the chromogenic reporter substrate. The enzyme was active in the pH range 7.0–11.0 with the optimum activity at pH 11.0. We noticed a pH dependent transformation in the nature of substrate consumption kinetics. The substrate saturation curves were hyperbolic in the pH range 7.0–9.0 but changed into sigmoid form at pH 10.0 and 11.0. Hill’s coefficients were >1. We also analysed the effect of pH on the structure of the enzyme. The circular dichroism spectra of the enzyme sample at pH 9.0 and 11.0 were coincidental in both far and near UV regions indicating conservation of the secondary and tertiary structures, respectively. The molecular weight of the enzyme sample was the same in both pH 7.0 and 11.0 indicating conservation of the quaternary structure. These results show that the kinetic transformation does not involve significant conformational changes. Cooperative binding of multiple substrate molecules may not be the basis for the sigmoid kinetics as only one substrate binding site has been noticed in the reported crystal structures ofB. subtilisGGT.

The conformational changes of haemoglobin on its binding to haptoglobin

1981 ◽  
Vol 46 (5) ◽  
pp. 1288-1295
Author(s):  
Barbora Dvořánková ◽  
Zdeněk Pavlíček
Keyword(s):  
Thin Layer ◽  
Conformational Changes ◽  
Peroxidase Activity ◽  
Quaternary Structure ◽  
Analogue Computer ◽  
Gel Chromatography ◽  
Human Haemoglobin ◽  
T State ◽  
Kinetics Of

The binding of human haemoglobin to human haptoglobin has been found to alter the conformation of haemoglobin. Spectrophotometric measurements, measuring of peroxidase activity, thin-layer gel chromatography and modelling on an analogue computer led to the conclusion that the binding of haemoglobin to haptoglobin was associated with a change in the quaternary structure of haemoglobin, with a transition from the R state to the T state. The kinetics of the conformational changes had an autocatalytic character.

Electron Microscopy and image reconstruction reveal the structural basis for spectrin's elastic properties

1992 ◽  
Vol 50 (1) ◽  
pp. 510-511
Author(s):  
Amy M. McGough ◽  
Robert Josephs
Keyword(s):  
Electron Microscopy ◽  
Elastic Properties ◽  
Conformational Changes ◽  
Quaternary Structure ◽  
Three Dimensional ◽  
Membrane Skeleton ◽  
Projection Algorithm ◽  
Structural Basis ◽  
Iterative Approximation ◽  
Membrane Skeletons

The remarkable deformability of the erythrocyte derives in large part from the elastic properties of spectrin, the major component of the membrane skeleton. It is generally accepted that spectrin's elasticity arises from marked conformational changes which include variations in its overall length (1). In this work the structure of spectrin in partially expanded membrane skeletons was studied by electron microscopy to determine the molecular basis for spectrin's elastic properties. Spectrin molecules were analysed with respect to three features: length, conformation, and quaternary structure. The results of these studies lead to a model of how spectrin mediates the elastic deformation of the erythrocyte.Membrane skeletons were isolated from erythrocyte membrane ghosts, negatively stained, and examined by transmission electron microscopy (2). Particle lengths and end-to-end distances were measured from enlarged prints using the computer program MACMEASURE. Spectrin conformation (straightness) was assessed by calculating the particles’ correlation length by iterative approximation (3). Digitised spectrin images were correlation averaged or Fourier filtered to improve their signal-to-noise ratios. Three-dimensional reconstructions were performed using a suite of programs which were based on the filtered back-projection algorithm and executed on a cluster of Microvax 3200 workstations (4).

Study of nickel-molybdenum catalysts for methanation of carbon monoxide

1980 ◽  
Vol 45 (3) ◽  
pp. 783-790 ◽  
Author(s):  
Petr Taras ◽  
Milan Pospíšil
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Mixed Oxides ◽  
Minor Component ◽  
Fast Neutrons ◽  
Scanning Calorimetry ◽  
Low Concentrations ◽  
Γ Rays ◽  
Molybdenum Catalysts ◽  
Kinetics Of

Catalytic activity of nickel-molybdenum catalysts for methanation of carbon monoxide and hydrogen was studied by means of differential scanning calorimetry. The activity of NiMoOx systems exceeds that of carrier-free nickel if x < 2, and is conditioned by the oxidation degree of molybdenum, changing in dependence on the composition in the region Mo-MoO2. The activity of the catalysts is adversely affected by irradiation by fast neutrons, dose 28.1 Gy, or by γ rays using doses in the region 0.8-52 kGy. The system is most susceptible to irradiation in the region of low concentrations of the minor component (about 1 mol.%). The dependence of changes in catalytic activity of γ-irradiated samples on the dose exhibits a maximum in the range of 2-5 kGy. The changes in catalytic activity are stimulated by the change of reactivity of the starting mixed oxides, leading to different kinetics of their reduction and modification of their adsorption properties. The irradiation of the catalysts results in lowered concentration of the active centres for the methanation reaction.

Kinetics of catalytic reduction of nitrogen oxide by carbon monoxide on CuO/Al2O3 catalyst

1983 ◽  
Vol 48 (11) ◽  
pp. 3202-3208 ◽  
Author(s):  
Zdeněk Musil ◽  
Vladimír Pour
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxide ◽  
Rate Equation ◽  
Catalytic Reduction ◽  
Zero Order ◽  
Spectroscopic Measurements ◽  
First Order ◽  
Ir Spectroscopic ◽  
Kinetics Of ◽  
Al2o3 Catalyst

The kinetics of the reduction of nitrogen oxide by carbon monoxide on CuO/Al2O3 catalyst (8.36 mass % CuO) were determined at temperatures between 413 and 473 K. The reaction was found to be first order in NO and zero order in CO. The observed kinetics are consistent with a rate equation derived from a mechanism proposed on the basis of IR spectroscopic measurements.

Kinetics of carbon monoxide methanation on a Ni/SiO2 catalyst

1990 ◽  
Vol 55 (7) ◽  
pp. 1678-1685
Author(s):  
Vladimír Stuchlý ◽  
Karel Klusáček
Keyword(s):  
Carbon Monoxide ◽  
Reaction Rate ◽  
Catalyst Activity ◽  
Adsorbed Hydrogen ◽  
Reaction Products ◽  
Co Methanation ◽  
Molar Ratios ◽  
Rate Determining Step ◽  
Higher Temperature ◽  
Kinetics Of

Kinetics of CO methanation on a commercial Ni/SiO2 catalyst was evaluated at atmospheric pressure, between 528 and 550 K and for hydrogen to carbon monoxide molar ratios ranging from 3 : 1 to 200 : 1. The effect of reaction products on the reaction rate was also examined. Below 550 K, only methane was selectively formed. Above this temperature, the formation of carbon dioxide was also observed. The experimental data could be described by two modified Langmuir-Hinshelwood kinetic models, based on hydrogenation of surface CO by molecularly or by dissociatively adsorbed hydrogen in the rate-determining step. Water reversibly lowered catalyst activity and its effect was more pronounced at higher temperature.

Kinetics of γ-alumina chlorination by carbon monoxide and chlorine

1982 ◽  
Vol 52 (1-3) ◽  
pp. 211-215 ◽  
Author(s):  
A. Tóth ◽  
I. Bertóti ◽  
T. Székely
Keyword(s):  
Carbon Monoxide ◽  
Kinetics Of

scholarly journals The kinetics of hœmoglobin VI -The competition of carbon monoxide and oxygen for hœmoglobin

1934 ◽  
Vol 115 (795) ◽  
pp. 473-495 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Reverse Reaction ◽  
Experimental Part ◽  
Kinetics Of ◽  
Broad Outline

The experimental part of the research to be described below is given in two main sections. Of these Section 1 deals with the results obtained in measurements of the rate of displacement of oxygen from combination with hœmoglobin by carbon monoxide. Section 2 gives, in corresponding fashion, the results for the reverse reaction, namely, the displacement of carbon monoxide from combination with hœmoglobin by oxygen. The theoretical aspects of theses two reactions have already been dealt with in broad outline at the end of Part IV, with which it will be assumed that the reader is fully acquainted. Some further considerations, however, arise and these are given in Section 3 of the present paper.

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