scholarly journals Kinetics of the activation of rat liver pyruvate kinase by fructose 1,6-disphosphate and methods for characterizing hysteretic transitions

1974 ◽  
Vol 141 (1) ◽  
pp. 119-125 ◽  
Author(s):  
H. Olin Spivey ◽  
Wayne Flory ◽  
Benigno D. Peczon ◽  
John P. Chandler ◽  
Roger E. Koeppe
Keyword(s):  
Pyruvate Kinase ◽  
Active Form ◽  
Enzyme Concentration ◽  
Type I ◽  
Numerical Techniques ◽  
First Order ◽  
First Order Transition ◽  
Model Equations ◽  
Kinetics Of ◽  
Increasing Function

1. Kinetics of fructose 1,6-diphosphate activation of liver pyruvate kinase type I inhibited with MgATP and l-alanine are described as a function of enzyme and fructose 1,6-diphosphate concentrations. These results can be explained by a single pseudo-first-order transition of the enzyme into an active form, independent of the enzyme concentration. This rate constant, kapp.=0.24s-1 with 0.02mm-fructose 1,6-diphosphate (t0.9 ≃ 10s where t0.9 is the time for 90% conversion), is an increasing function of fructose 1,6-diphosphate concentration far beyond that needed to maximally activate enzyme equilibrated with fructose 1,6-diphosphate (about 20μm). 2. The model equations are best analysed with numerical techniques which are described. These techniques are useful in studying similar slow transients frequently observed in stopped-flow studies of enzymes. 3. Shorter transients (t0.9=0.5–1.5s) were observed in the kinetic response of the enzyme to the addition of MgATP or phosphoenolpyruvate, but were not further characterized.

Kinetics and mechanisms of oxidations by metal ions. Part IV. Oxidation of phenylphosphinic acid by aquavanadium(V) ions

1985 ◽  
Vol 63 (3) ◽  
pp. 663-666 ◽  
Author(s):  
Raj Narain Mehrotra
Keyword(s):  
Acidic Solution ◽  
Active Form ◽  
Equilibrium Mixture ◽  
Order Rate Constant ◽  
First Order ◽  
Inactive Form ◽  
Pseudo First Order ◽  
Independent Path ◽  
Kinetics Of ◽  
Vanadium Ion

The kinetics of the oxidation of phenylphosphinic acid by quinquevalent vanadium ion have been investigated in aqueous perchlorate media under pseudo-first order conditions (phenylphosphinic acid in excess). The reaction has a first order dependence in [V(V)] and [phenylphosphinic acid] and the observed pseudo-first order rate constant kobs is given by kobs = a + b[H+].The acid-independent path is considered to be due to the reaction between VO2+ (aq.) and C6H5P:(OH)2, the active form of phenylphosphinic acid, while the reaction between V(OH)32+ (aq.) and C6H5P(O)(OH)H, the inactive form of phenylphosphinic acid, is considered to explain the acid-dependent path. Phenylphosphinic acid in aqueous acidic solution is known to exist as an equilibrium mixture of the active and inactive forms. The composite activation and thermodynamic parameters associated with the constants a and b are reported.

A new calculation of the kinetics of the renneting reaction

1988 ◽  
Vol 55 (4) ◽  
pp. 521-528 ◽  
Author(s):  
Douglas G. Dalgleish
Keyword(s):  
Molecular Weight ◽  
Surface Layer ◽  
Analytical Solution ◽  
Enzyme Concentration ◽  
Detailed Calculation ◽  
Repulsive Potential ◽  
First Order ◽  
Coagulation Process ◽  
Kinetics Of

SummaryA detailed calculation of the growth of molecular weight during the renneting of milk is given, based on a first-order breakdown of κ-casein followed by development of instability caused either by a decrease in the intermicellar repulsive potential or by the formation of holes in the stabilizing surface layer of the micelles. Unlike most of the models which have been described, this model allows a complete analytical solution. The solution is, however, complex and difficult to use simply, although it is shown that the calculations are in accord with experimental observations of the dependence of the coagulation process upon the enzyme concentration and the concentration of the milk. The calculations are also compared with those from other models of the reaction.

Kinetics of the first-order transition in stage 1 rubidium graphite intercalation compound

1989 ◽  
Vol 34 (1-3) ◽  
pp. 323-328 ◽  
Author(s):  
Naoto Metoki ◽  
Hiroyoshi Suematsu ◽  
Youichi Murakami ◽  
Yasuhiro Ohishi ◽  
Yasuhiko Fujii
Keyword(s):  
Intercalation Compound ◽  
Order Transition ◽  
Graphite Intercalation Compound ◽  
First Order ◽  
Graphite Intercalation ◽  
First Order Transition ◽  
Stage 1 ◽  
Kinetics Of

scholarly journals Remediation of Crystal Violet Dye Aqueous Solution Using Agro Waste Based Activated Carbon: Equilibrium and Kinetics Studies

2020 ◽  
pp. 1-11
Author(s):  
Chukwunonso Chukwuzuloke Okoye ◽  
Okechukwu Dominic Onukwuli ◽  
Chinenye Faith Okey- Onyesolu ◽  
Ifeoma Amaoge Obiora- Okafo
Keyword(s):  
Aqueous Solution ◽  
Kinetic Data ◽  
Adsorption Process ◽  
Particle Diffusion ◽  
Type I ◽  
First Order ◽  
Equilibrium And Kinetics ◽  
Equilibrium Data ◽  
Intra Particle Diffusion ◽  
Kinetics Of

Remediation of crystal violet (CV) dye aqueous solution was attempted using acid activated raphia hookeri seeds (AARHS) as adsorbent. Adsorption equilibrium and kinetics of CV dye uptake onto AARHS were examined in series of experimental runs, and effects of contact time and initial CV dye concentrations were investigated at different solution temperatures (303 K, 313 K and 323 K). Equilibrium and kinetic data modeling of the adsorption process was performed using selected theoretical methods. Four different forms of Langmuir (type I, II, III and IV) and Freundlich isotherms were considered for fitting the equilibrium data while zero order, first order, pseudo-first order (PFO), second order, types I, II, III and IV pseudo-second order (PSO) and intra-particle diffusion models were selected to describe the kinetics of the adsorption process. Error functions including coefficient of determination (R2), root mean square error (RMSE), chi square (χ2) and average relative error (ARE) were employed to reveal model of best fit. Results obtained from error value computations show that the equilibrium data best followed Freundlich isotherm, which indicates multilayer adsorption of CV dye onto AARHS. The calculated Freundlich’s adsorption intensity values at different temperatures reveal the favourability of the adsorption process. PSO type I, II and IV best fitted the kinetic data compared to other investigated models. Intra-particle diffusion plots depict that the adsorption process of CV dye onto AARHS is a two-step process and also, intra-particle diffusion is not the only rate-limiting step.

Isotopic Effect on the Kinetic of Thermal Denaturation of Ceruloplasmin

1985 ◽  
Vol 40 (7-8) ◽  
pp. 551-554 ◽  
Author(s):  
L. Sportelli ◽  
A. Desideri ◽  
A. Campaniello
Keyword(s):  
Thermal Denaturation ◽  
Charge Transfer Band ◽  
Type I ◽  
Protein Solution ◽  
First Order ◽  
Irreversible Denaturation ◽  
Optical Density Change ◽  
Kinetics Of ◽  
Protein Active Site ◽  
Denaturation Process

Abstract The kinetics of thermal denaturation of ceruloplasmin in water and in water with different percentage of D20 in the temperature range 25 - 85 °C, following the optical density change of the 610 nm charge transfer band of the protein has been investigated. A temperature Tt ≃ 65 °C above which an irreversible denaturation process of the protein active site takes place has been found. The kinetics of the denaturation process of the protein are fitted by two first order reactions, which have been assigned to a different thermal denaturation behaviour of the two Cu2+ type I sites existing in the protein. Addition of D2O to the protein solution affects the two kinetics in a different way, i.e. the rate of one of them is increased whilst that of the other is decreased. The different effect of D2O on the kinetics of disruption of the two copper sites is discussed in terms of different location and degree of hydrophobicity of the two Cu2+ type I sites.

scholarly journals Kinetic properties of rat liver pyruvate kinase at cellular concentrations of enzyme, substrates and modifiers

1974 ◽  
Vol 141 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Wayne Flory ◽  
Benigno D. Peczon ◽  
Roger E. Koeppe ◽  
H. Olin Spivey
Keyword(s):  
Pyruvate Kinase ◽  
Rat Liver ◽  
Kinase Activity ◽  
Enzyme Concentration ◽  
Kinetic Properties ◽  
Type I ◽  
Enzyme Properties ◽  
Pyruvate Kinase Activity ◽  
Enzyme Substrates ◽  
Cellular Control

Kinetic properties of rat liver pyruvate kinase type I at pH7.5 and 6.5 were studied with physiological ranges of substrates, modifiers and Mg2+ concentrations at increasing enzyme concentrations, including the estimated cellular concentrations (approx. 0.1mg/ml). Enzyme properties appear unaffected by increased enzyme concentration if phosphoenolpyruvate, fructose 1,6-diphosphate and inhibitors are incubated with enzyme before starting the reaction with ADP. Our data suggest that minimum cellular concentrations of MgATP and l-alanine provide virtually complete inhibition of pyruvate kinase I at pH7.5. The most likely cellular control of existing pyruvate kinase I results from the strong restoration of enzyme activity by the small physiological amounts of fructose 1,6-diphosphate. Decreasing the pH to 6.5 also restores pyruvate kinase activity, but to only about one-third of its activity in the presence of fructose 1,6-diphosphate. Neither pyruvate nor 2-phosphoglycerate at cellular concentrations inhibit the enzyme significantly.

The kinetics of the rennin-casein reaction in abnormal cow's milk and milks of some other species and of the action of rennet substitutes on normal cow's milk

1962 ◽  
Vol 29 (3) ◽  
pp. 297-305 ◽  
Author(s):  
J. C. Oosthuizen
Keyword(s):  
Sodium Caseinate ◽  
Enzyme Concentration ◽  
Reaction Rate Constant ◽  
Cow’S Milk ◽  
Reaction Equation ◽  
Cow's Milk ◽  
First Order ◽  
First Order Kinetics ◽  
Constant Rate ◽  
Kinetics Of

SummaryIn earlier papers it was shown that the fall in viscosity of milk and caseinate solutions acted on by rennet, follows a first-order reaction equation. The reaction rate constant has been found to be independent of the source of the caseinate substrate used. This seems to be true not only for caseinate from normal cow's milk but also from colostrum, slow-clotting cow's milk and even the milk of buffaloes, sheep and probably goats.With solutions of caseinate from sow's milk the reaction kinetics and the proportional viscosity loss were similar to those of cow's caseinate but the rate constants were much lower. Rennet showed no measurable reaction with human, whale, mare or rhinoceros caseinates but produced a constant rate of fall in the viscosity of a camel caseinate for more than an hour from rennetting.Vegetable and microbiological rennet substitutes also produce a fall in the viscosity of sodium caseinate and the reactions follow first-order kinetics. They differ from cheese rennet in that the proteolysis involved is stronger and is not as limited as that of rennin since they attack at least twice as much of the casein ensemble. This might suggest a mixture of enzymes but since the proportionality between enzyme concentration and k1 was very close this seems unlikely.

scholarly journals KINETICS OF SOLID-STATE MULLITE SYNTHESIS FROM ACTIVATED PRECURSORS

2018 ◽  
Vol 59 (1) ◽  
pp. 36
Author(s):  
N.F. Kosenko ◽  
N.V. Filatova ◽  
Yu.V. Pimkov
Keyword(s):  
Solid State ◽  
Active Form ◽  
Effective Rate ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
First Order ◽  
Co Precipitation ◽  
Kinetics Of ◽  
Product Accumulation ◽  
Energy Activation

The solid-state synthesis kinetics of the mullite 3Al2O3∙2SiO2 from aluminium hydroxide and metasilicic acid was studied. Hydrated oxides obtained in an active form as a result of a mechanical activation or co-precipitation (precursors) were subjected to a high-temperature treatment. The reaction rate was described by the kinetic first-order equation. Effective rate constants and energy activation were determined. The positive action of mullite seed crystals on the product accumulation was confirmed.

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