scholarly journals PHYSICOCHEMICAL PROPERTIES OF THE PROTEOLYTIC ENZYME FROM THE LATEX OF THE MILKWEED, ASCLEPIAS SPECIOSA TORR. SOME COMPARISONS WITH OTHER PROTEASES

1940 ◽  
Vol 23 (3) ◽  
pp. 289-300 ◽  
Author(s):  
Theodore Winnick ◽  
Alva R. Davis ◽  
David M. Greenberg
Keyword(s):  
Reaction Rate ◽  
Enzyme Concentration ◽  
Second Order ◽  
Urea Solution ◽  
Reaction Products ◽  
Clotting Time ◽  
Milk Clotting ◽  
Enzyme Substrate ◽  
Asclepias Speciosa ◽  
Kinetics Of

1. The kinetics of milk clotting by asclepain, the protease of Asclepias speciosa, were investigated. At higher concentrations of enzyme, the clotting time was inversely proportional to the enzyme concentration. 2. The digestion of casein and hemoglobin in 6.6 M urea by asclepain follows the second order reaction rate. The rate was roughly second order for casein in water. 3. Evaluation of the nature of the enzyme-substrate intermediate indicates that one molecule of asclepain combines with one molecule of casein or hemoglobin in urea solution. 4. Inhibition by the reaction products was deduced from the fact that the digestion velocity of hemoglobin in urea solution varied with the asclepain concentration in agreement with the Schütz-Borissov rule.

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 oxidation of cis-bis(ethylenediamine)isothiocyanatonitrocobalt(III) ion with peroxodisulphate

1979 ◽  
Vol 44 (12) ◽  
pp. 3588-3594 ◽  
Author(s):  
Vladislav Holba ◽  
Olga Volárová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Oxidation Kinetics ◽  
Reaction Rate ◽  
Salt Effect ◽  
Activation Parameters ◽  
Reaction Products ◽  
Kinetics Of Oxidation ◽  
Thermodynamic Activation Parameters ◽  
Kinetics Of

The oxidation kinetics of cis-bis(ethylenediamine)isothiocyanonitrocobalt(III) ion with peroxodisulphate was investigated in the medium of 0.01 M-HClO4 in dependence on the ionic strength and temperature and the reaction products were identified. Extrapolated values of thermodynamic activation parameters were determined from the temperature dependence of the rate constants extrapolated to zero ionic strength. The distance of the closest approach was estimated for the reacting ions by evaluating the primary salt effect. To elucidate the mechanism, the influence of the cyclic polyether 18-crown-6 on the reaction rate was followed.

Kinetics and mechanism of bromination of styrenes

1967 ◽  
Vol 45 (2) ◽  
pp. 167-173 ◽  
Author(s):  
Keith Yates ◽  
W. V. Wright
Keyword(s):  
Activation Parameters ◽  
Second Order ◽  
Linear Free Energy Relationship ◽  
Reaction Products ◽  
Order Process ◽  
Third Order ◽  
Linear Free Energy ◽  
Reaction Constant ◽  
Relationship Of ◽  
Kinetics Of

The kinetics of bromination of six substituted styrènes (3-fluoro-, 3-chloro-, 3-bromo-, 3,4-dichloro-, 3-nitro-, and 4-nitro-) in anhydrous acetic acid have been investigated at several temperatures. At 25.3 °C the reactions follow the rate expression [Formula: see text]The rate constants for the second order process show a good linear free energy relationship of the log k versus σ type with ρ = − 2.24. (The value obtained at 35.3 °C is − 1.93.) No simple rate-substituent dependence is obtained for the more complex third order process. Activation parameters have been obtained for the second order brominations, the ΔS≠ values being large and negative. Bromination of styrene in the presence of a large excess of acetate or nitrate gives only two products in each case, the α,β-dibromide and the α –acetoxy β-bromide or α -nitrato- β -bromide respectively.The magnitude of the reaction constant ρ, the values of ΔS≠, and the reaction products all support a mechanism involving a highly unsymmetrical bromonium ion intermediate.

Kinetics and thermodynamics of the reaction between thyroxine and antithyroxine antiserum under the conditions of radioimmunoanalysis

1982 ◽  
Vol 47 (8) ◽  
pp. 2077-2086
Author(s):  
Peter Talán ◽  
Juraj Mucha
Keyword(s):  
Reaction Rate ◽  
Serum Proteins ◽  
Relative Rate ◽  
Order Reaction ◽  
Second Order ◽  
Second Order Reaction ◽  
Reaction Enthalpy ◽  
Thermodynamics And Kinetics ◽  
Relative Rate Constants ◽  
Kinetics Of

Thermodynamics and kinetics of the reaction between thyroxine and antithyroxine antiserum has been studied using the concentration and temperature conditions usual in the radioimmunoanalysis. The reaction is assumed to be homogeneous and of the second order. Because of the initial concentrations of thyroxine and of the free bonds of the heterogeneous population of antibodies present in the used antiserum the rate constant equation for second-order reaction has been used in the integrated form. The relative rate constants have been obtained and the activation energy of the reaction in absence of the serum proteins in the reaction mixture or, respectively, in the presence of the euthyroidic serum has been calculated. The nature of the effect of so-called deblockators (J) (8-anilino-1-naphthalene sulphonic acid and tiomersal) on the reaction rate and on the change of the reaction enthalpy (or entropy) has also been investigated. The association constant of this reaction has been evaluated from the radioimmunoanalytical data transformed by the Scatchard relation, modified for the conditions of thyroxine radioimmunoanalysis.

scholarly journals Enzymatic Kinetics of Enzymatically Extruded Degerminated Maize Using Glucamylase

2018 ◽  
Vol 7 (2) ◽  
pp. 10 ◽  
Author(s):  
Chengye Ma ◽  
Shuangshuang Yu ◽  
Yuyan Fan ◽  
Shuhua Wu ◽  
Zhehao Zhang ◽  
...  
Keyword(s):  
Incubation Time ◽  
Reaction Rate ◽  
Reaction Rates ◽  
Enzyme Concentration ◽  
Kinetics Equation ◽  
Enzymatic Kinetics ◽  
Substrate Ph ◽  
Kinetics Of

In this study, the reaction rates of native degerminated maize, extruded degerminated maize and enzymatically extruded degerminated maize using glucoamylase were evaluated and the extrudate models were investigated. The effects of enzyme concentration, substrate pH, temperature and incubation time on the reaction rates were studied. The Lineweaver–Burk equation was used in order to obtain the parameters of the kinetics equation of catalysed hydrolysis. The results show that NDM’s vm is 0.0845g/(mL·min) and km is 0.0032, EDM’s vm is 0.6251g/(mL·min) and km is 0.0167, EEDM’s vm is 1.897g/(mL·min) and km is 0.0240. The reaction rate of EEDM is quicker than those of NDM and EDM. The kinetics equation of EEDM is in accordance with the Michaelis–Menten equation.

Kinetics of hydrolysis and rearrangements of S-acylthiouronium salts

1982 ◽  
Vol 47 (10) ◽  
pp. 2702-2710 ◽  
Author(s):  
Jaromír Kaválek ◽  
Jaroslav Novák ◽  
Vojeslav Štěrba
Keyword(s):  
Hydrochloric Acid ◽  
Dilute Hydrochloric Acid ◽  
Reaction Rate ◽  
Acetyl Derivative ◽  
Reaction Products ◽  
Acid Media ◽  
Hydroxyl Ion ◽  
Hydrochloric Acid Media ◽  
Kinetics Of ◽  
Acyl Derivatives

Kinetics of transformation of S-acetyl- and S-benzoylisothiouronium chlorides have been followed, and its reaction products in dilute hydrochloric acid media and aqueous buffers have been identified. In dilute hydrochloric acid the reaction rate is pH-independent, and the acetyl derivative reacts 8 times as rapidly as the benzoyl derivative. In acetate and phosphate buffers the decomposition rate of the both derivatives increases linearly with the buffer concentration. In acetate buffers the reaction rate is pH-independent, and acetate ion reacts as a nucleophile. In phosphate buffers the rate increases with increasing pH. The reaction catalyzed by the basic buffer component produces thiourea and carboxylic acid, that catalyzed by hydroxyl ion produces N-acetyl- or N-benzoylthiourea. The solvolysis rates of both S-acyl derivatives depend on percent composition of water-methanol solvent. The maximum solvolysis rate is reached in methanol with 25% (v/v) water.

scholarly journals Kinetics of an enzyme reaction in which both the enzyme-substrate complex and the product are unstable or only the product is unstable

1994 ◽  
Vol 303 (2) ◽  
pp. 435-440 ◽  
Author(s):  
C Garrido-del Solo ◽  
F García-Cánovas ◽  
B H Havsteen ◽  
E Valero ◽  
R Varón
Keyword(s):  
Computer Simulation ◽  
Data Analysis ◽  
Kinetic Data ◽  
Enzyme Reaction ◽  
Enzyme Concentration ◽  
Substrate Complex ◽  
Use Of Data ◽  
Enzyme Substrate ◽  
Experimental Errors ◽  
Kinetics Of

A kinetic analysis of the Michaelis-Menten mechanism has been made for the case in which both the enzyme-substrate complex and the product are unstable or only the product is unstable, either spontaneously or as the result of the addition of a reagent. This analysis allows the derivation of equations which under conditions of limiting enzyme concentration relate the concentration of all of the species to the time. A kinetic data analysis is suggested, which leads to the evaluation of the kinetic parameters involved in the reaction. The analysis is based on the equation which describes the formation of products with time and one's experimental progress curves. We demonstrate the method numerically by computer simulation of the reaction with added experimental errors and experimentally by the use of data from the kinetic study of the action of tyrosinase on dopamine.

Proteolytic and polymerase activity of thrombin

1960 ◽  
Vol 198 (1) ◽  
pp. 173-179 ◽  
Author(s):  
Ricardo H. Landaburu ◽  
Walter H. Seegers
Keyword(s):  
Fibrin Clot ◽  
Polymerase Activity ◽  
Urea Solution ◽  
Polymerization Time ◽  
Reaction Products ◽  
Clotting Time ◽  
Fibrin Monomer ◽  
As If

In addition to splitting peptides from fibrinogen, thrombin is necessary for the polymerization of fibrin monomer. Thrombin also uses fibrin as a substrate and eventually the clot may lyse. On the basis of these views, previous equations used to outline the events when thrombin and fibrinogen are mixed can be revised as follows: Proteolysis: F + T ⇆ f + P + T (1) Polymerization: Nf + T ⇆ NfT (2) (fibrin clot) Proteolysis: NfT → Inf + T + P2 (3) F is fibrinogen, T is thrombin, f is fibrin monomer, P is peptides and carbohydrates, N is any number, Inf is inactive fibrin monomer, and P2 is peptides or any reaction products. As the thrombin concentration increases the polymerization time becomes shorter. TAMe retards the polymerization time. For a given thrombin concentration the clotting time of fibrinogen may be inversely proportional to the concentration of fibrinogen. Most of the clotting time is accounted for as polymerization time, but the amount of thrombin required for the latter is relatively small. In 3 m urea solution thrombin may irreversibly lose its activity. When protected by a substrate such as TAMe, fibrinogen or fibrin, thrombin is active in urea solution. The activity then depends upon TAMe concentration under conditions when the enzyme behaves as if saturated with the substrate. To have this activity in urea solution the substrate must be in the urea before the thrombin is added. Esterase thrombin also uses fibrin as a substrate; it is, however, not a polymerase. It does not use fibrinogen as a substrate.

Decomposition of BrO studied by kinetic spectroscopy

1970 ◽  
Vol 48 (22) ◽  
pp. 3487-3490 ◽  
Author(s):  
J. Brown ◽  
George Burns
Keyword(s):  
Activation Energy ◽  
Total Pressure ◽  
Reaction Rate ◽  
Second Order ◽  
Kcal Mole ◽  
Kinetic Spectroscopy ◽  
Reaction Proceeds ◽  
One Step ◽  
Kinetics Of ◽  
Activated Complex

Kinetics of BrO decomposition was studied between 293 and 673 °K using the technique of kinetic spectroscopy. At 293 °K the reaction rate is second order with respect to BrO and is independent of [Br2], [O2], and total pressure of diluent gas. The activation energy for decomposition obtained from rate measurements between 293 and 450 °K is 0.65 ± 0.05 kcal/mole. Above 450 °K this activation energy appears to increase to 4.5 kcal/mole. It is shown that, although kinetically the ClO and BrO decompositions are similar, the mechanism for BrO decomposition below 450 °K is much simpler than that of ClO. The reaction proceeds, most likely, via one step: 2 BrO → 2 Br + O2, with Br2O2 being an activated complex, which has either linear or staggered configuration. ClO and BrO decomposition is compared with [Formula: see text] reaction.

Notizen:Kinetics of Ester-interchange between Methyl Acetate and Ethanol

1972 ◽  
Vol 27 (10) ◽  
pp. 1529-1530 ◽  
Author(s):  
T. Rao ◽  
B. Gandhe
Keyword(s):  
Reaction Rate ◽  
Methyl Acetate ◽  
Second Order ◽  
Energy Of Activation ◽  
Chromatographic Technique ◽  
Kcal Mole ◽  
Specific Reaction Rate ◽  
Ester Interchange ◽  
Specific Reaction ◽  
Kinetics Of

Abstract Kinetics of ester-interchange between methyl acetate and ethanol has been studied in the range 80 - 105°, using gas chromatographic technique. The reaction is of the second order, and the specific reaction rate is 29.6-10-8 l/mole-sec at 105°. The energy of activation is 16.7 kcal/mole and the en-tropy of activation is -44.3 cal/mole-deg.

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