scholarly journals THE USE OF DIFFERENT MEASURES OF REACTION VELOCITY IN THE STUDY OF THE KINETICS OF BIOCHEMICAL REACTIONS

1937 ◽  
Vol 120 (2) ◽  
pp. 555-574
Author(s):  
Oscar Bodansky
Keyword(s):  
Biochemical Reactions ◽  
Reaction Velocity ◽  
Kinetics Of

THE KINETICS OF CUPRENE GROWTH

1950 ◽  
Vol 28b (7) ◽  
pp. 358-372
Author(s):  
Cyrias Ouellet ◽  
Adrien E. Léger
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Carbon Monoxide ◽  
Apparent Activation Energy ◽  
Copper Catalyst ◽  
Maximum Velocity ◽  
Static System ◽  
Reaction Velocity ◽  
First Order ◽  
Kinetics Of

The kinetics of the polymerization of acetylene to cuprene on a copper catalyst between 200° and 300 °C. have been studied manometrically in a static system. The maximum velocity of the autocatalytic reaction shows a first-order dependence upon acetylene pressure. The reaction is retarded in the presence of small amounts of oxygen but accelerated by preoxidation of the catalyst. The apparent activation energy, of about 10 kcal. per mole for cuprene growth between 210° and 280 °C., changes to about 40 kcal. per mole above 280 °C. at which temperature a second reaction seems to set in. Hydrogen, carbon monoxide, or nitric oxide has no effect on the reaction velocity. Series of five successive seedings have been obtained with cuprene originally grown on cuprite, and show an effect of aging of the cuprene.

scholarly journals H. The Kinetics of Enzyme Cascade Systems General kinetics of enzyme cascades

1969 ◽  
Vol 173 (1032) ◽  
pp. 411-420 ◽  
Keyword(s):  
Product Formation ◽  
Coagulation Cascade ◽  
Lag Phase ◽  
Open Type ◽  
Reaction Velocity ◽  
Cascade Systems ◽  
Enzyme Cascade ◽  
Enzyme Cascades ◽  
Kinetics Of ◽  
Product Relation

The theory of the kinetics of enzyme cascades is developed. Two types of cascades are recognized, one in which the products are stable ( open cascades ) and another in which the products are broken down ( damped cascades ). It is shown that it is a characteristic of a cascade that the final product appears after a certain lag phase. After this lag phase, the velocity of product formation can be very rapid. It is shown that whereas open cascades will always show a complicated time–product relation, damped cascades can under certain circumstances resemble a simple enzymic reaction. Because the relation between the over-all reaction velocity in the extrinsic coagulation cascade and the concentration of any of the proenzymes in this cascade is a hyperbolic one, it is concluded that this cascade is of the damped type rather than the open type.

scholarly journals Kinetics of the base-catalyzed halogenation of some ketones and esters

1949 ◽  
Vol 198 (1054) ◽  
pp. 308-322 ◽  
Keyword(s):  
Charge Distribution ◽  
Ethyl Acetoacetate ◽  
Kinetic Data ◽  
Kinetic Measurements ◽  
Reaction Velocity ◽  
Halogen Atoms ◽  
Basic Catalysts ◽  
Kinetics Of ◽  
Large Substituent ◽  
Bromine Substitution

Kinetic measurements have been made at 25 ° C on the halogenation of benzoylacetone, acetylacetone, ethyl acetoacetate, ethyl α-bromoacetoacetate and diethyl bromomalonate. A method is described for analyzing the kinetic data and obtaining the rates of substitution of successive halogen atoms without isolating the partly halogenated derivatives. The reaction velocities measured are all independent of the halogen concentration, and represent the rates of ionization of the ketonic substances in presence of basic catalysts. The results obtained conform in general to the regularities previously found for this type of reaction, but anomalies are found in some instances; these are related to the interaction of large substituent groups in both substrate and anion catalyst. The effect of bromine substitution in increasing the reaction velocity is shown to decrease as the reactivity of the ketone increases, and this is explained in terms of the charge distribution in the anion of the substrate.

Levitated Drop Microreactors for Biochemical Kinetics

2012 ◽  
Vol 560-561 ◽  
pp. 395-400
Author(s):  
Alexander Scheeline ◽  
Woo Hyuck Choi ◽  
Edward T. Chainani ◽  
Khan T. Ngo
Keyword(s):  
Free Radicals ◽  
Chemical Analysis ◽  
Sample Preparation ◽  
Chemical Processes ◽  
Materials Processing ◽  
Biochemical Reactions ◽  
Biochemical Kinetics ◽  
Catalyzed Reactions ◽  
Enzyme Catalyzed Reactions ◽  
Kinetics Of

Ultrasonically-levitated drops have been widely studied for materials processing and for sample preparation for chemical analysis. We report on the development of such drops for study of kinetics of enzyme-catalyzed reactions and other chemical processes. We review how to simply and reliably levitate drops, discuss why such drops are desirable for studying biochemical reactions, especially those generating or consuming free radicals, and report progress towards routine kinetics measurements in microliter drops.

scholarly journals The kinetics of the combustion of methane

1936 ◽  
Vol 157 (892) ◽  
pp. 503-525 ◽  
Keyword(s):  
Induction Period ◽  
Time Curve ◽  
Kinetics Of Oxidation ◽  
Reaction Velocity ◽  
Oxidation Of Methane ◽  
Pressure Time ◽  
Reactive Mixture ◽  
A Chain ◽  
Combustion Processes ◽  
Kinetics Of

The kinetics of oxidation of methane at pressures comparable with atmospheric pressure presents many features of great interest and of considerable importance to the elucidation of the nature of combustion processes in general. The facts which have accumulated to date, though fairly precise and definite, require in some cases amplification and further study in view of the realization that combustion has the character of a chain reaction. It has been found that the temperature of ignition of methane, which lies in the region 700-800°C., is dependent on the composition and total pressure of the mixture. For equimolecular mixtures of CH 4 and O 2 , no lower limit phenomena of the kind associated with hydrogen or carbon monoxide ignition have been observed. Below the ignition limit there is a readily measurable reaction velocity, and it was shown by Fort and Hinshelwood that the pressure-time curve is comprised of three distinct parts: ( a ) an induction period of several seconds’ or minutes’ duration, during which almost no reaction can be detected; ( b ) a period of acceleration to a steady velocity, followed by ( c ) a gradual decline of the velocity to zero as the reactants are used up. Fort and Hinshelwood showed that the velocity during the reaction period was much more dependent on the pressure of methane than that of oxygen. They further established the fact that the reaction is almost completely inhibited by packing the vessel with pieces of quartz tubing. Bone and Allum showed that the most reactive mixture consists of methane and oxygen in the ratio 2:1, the induction period being shortest and the reaction velocity greatest for this proportion. It was further found that the reaction is subject to sensi­tization, small quantities of nitrogen peroxide, iodine, or formaldehyde practically removing the induction period and increasing the reaction rate. An analysis of the products of the reaction showed that it followed the general course: CH 4 + 1½ O 2 = 2H 2 O + CO. (I)

scholarly journals The kinetics of hæmoglobin. III.—The velocity with which oxygen combines with reduced hæmoglobin

1925 ◽  
Vol 107 (744) ◽  
pp. 654-683 ◽  
Keyword(s):  
Unit Volume ◽  
Salt Content ◽  
Hemoglobin Concentration ◽  
Spectroscopic Observation ◽  
Mixed Solution ◽  
Dissociation Curve ◽  
Reaction Velocity ◽  
Velocity Constant ◽  
Mixing Chamber ◽  
Kinetics Of

The velocity with which oxygen dissociates from its combination with hæmoglobin, and the factors upon which the velocity-constant of this reaction depends, have already been investigated by us in some detail in the second of the present series of papers (1). Since then we have been engaged in a similar inquiry into the velocity of the reverse reaction, i. e ., the combination of oxygen with reduced hæmoglobin. The scope of the investigation, which we are now about to describe, was as follows:— (α) To determine the order of the reaction between oxygen and hæmoglobin (see p. 663). (β) To compare the value of the velocity-constant for the combination of O 2 + Hb ______________________________________________________ the velocity-constant for the dissociation of O 2 .Hb→ with the value of the equilibrium-constant of the reaction as determined from the dissociation curve. (γ) To study the effect of (i) p H (ii) temperature, (iii) light, and (iv) salt content upon the velocity of the reaction between O 2 and hæmoglobin. The general methods adopted were similar to those used in studying the rate of dissociation of oxyhæmoglobin. One solution (I) consisted of water containing a considerable quantity of oxygen in solution, whereas the other solution (II) consisted of reduced hæmoglobin. These were driven by separate jets into the mixing chamber of the reaction velocity apparatus (2 and 3), and after mixing travelled steadily with known velocity down the observation tube. Spectroscopic observation of the ratio of oxyhæmoglobin to reduced hemoglobin concentration at various points of the tube, together with a knowledge of the rate of linear flow and of the total amount of (i) oxygen and (ii) hæmoglobin in unit volume of the mixed solution, gave us all the data required for the measurement of the velocity of the reaction.

scholarly journals KINETICS OF THE BIOLUMINESCENT REACTION IN CYPRIDINA. II

1922 ◽  
Vol 4 (5) ◽  
pp. 535-558 ◽  
Author(s):  
William R. Amberson
Keyword(s):  
Heterogeneous System ◽  
Decay Curve ◽  
Enzyme Concentration ◽  
Complete Agreement ◽  
Theoretical Expectation ◽  
Reaction Velocity ◽  
Monomolecular Reaction ◽  
Straight Line ◽  
Experimental Values ◽  
Kinetics Of

1. The decay curve of the light produced in the course of the luminescent reaction in Cypridina is, after the first second, in complete agreement with the theoretical expectation for a monomolecular reaction, if light intensity at any instant is assumed to be proportional to reaction velocity at that instant. It is shown that for such a reaction log I = - kt + log Ak and that the experimental values satisfy this equation. 2. The first second or two of the reaction is characterized by a brilliant initial flash, whose value is much too high to accord with the succeeding intensities and with the above formula. It is suggested that this initial high reaction velocity is an indication of a heterogeneous system. 3. Identical solutions run simultaneously give decay curves which check within the limits of the photographic error. 4. Stirring does not affect the reaction velocity or the form of the decay curve. 5. Reaction velocity is proportional to enzyme concentration, over the range of concentrations used in the study. 6. Changes in the concentration of the substrate do not affect the value of k, when all other factors are held constant. A diminution of luciferin concentration results only in a decrease in the value of the y-intercept, Log Ak, the two straight line plottings for two different concentrations being parallel. 7. The temperature coefficient is high, being about 4.5 for the 15–25° interval, and 3.0 for the 25–35° interval.

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