KINETICS OF THE ENZYMICALLY-CATALYZED OXIDATION OF INDOLEACETIC ACID

1956 ◽  
Vol 34 (6) ◽  
pp. 1233-1250 ◽  
Author(s):  
G. A. Maclachlan ◽  
E. R. Waygood
Keyword(s):  
Indoleacetic Acid ◽  
Aryl Radical ◽  
Reaction Sequence ◽  
Final Reaction Product ◽  
Final Reaction ◽  
A Chain ◽  
Kinetics Of ◽  
Catalyzed Oxidation

A study of the kinetics of the enzymically-catalyzed decarboxylation and oxidation of indoleacetic acid has provided evidence that it is a chain autoxidation initiated and propagated by two enzyme-controlled peroxidations. The following reaction sequence occurs:[Formula: see text]where S—COOH = indoleacetic acid; S∙ = skatole radical; SO2∙ = oxidized skatole radical or indole peroxide; SO2H = final reaction product; ROH = phenolic cofactor, i.e., resorcinol; RO∙ = semiquinol or aryl radical.

KINETICS OF THE ENZYMICALLY-CATALYZED OXIDATION OF INDOLEACETIC ACID

1956 ◽  
Vol 34 (1) ◽  
pp. 1233-1250 ◽  
Author(s):  
G. A. Maclachlan ◽  
E. R. Waygood
Keyword(s):  
Indoleacetic Acid ◽  
Aryl Radical ◽  
Reaction Sequence ◽  
Final Reaction Product ◽  
Final Reaction ◽  
A Chain ◽  
Kinetics Of ◽  
Catalyzed Oxidation

A study of the kinetics of the enzymically-catalyzed decarboxylation and oxidation of indoleacetic acid has provided evidence that it is a chain autoxidation initiated and propagated by two enzyme-controlled peroxidations. The following reaction sequence occurs:[Formula: see text]where S—COOH = indoleacetic acid; S∙ = skatole radical; SO2∙ = oxidized skatole radical or indole peroxide; SO2H = final reaction product; ROH = phenolic cofactor, i.e., resorcinol; RO∙ = semiquinol or aryl radical.

THE ENZYMICALLY CATALYZED OXIDATION OF INDOLEACETIC ACID

1956 ◽  
Vol 34 (6) ◽  
pp. 905-926 ◽  
Author(s):  
E. R. Waygood ◽  
Ann Oaks ◽  
G. A. Maclachlan
Keyword(s):  
Indoleacetic Acid ◽  
Maleic Hydrazide ◽  
Organic Peroxide ◽  
Horse Radish Peroxidase ◽  
Reaction Sequence ◽  
Leaf Extracts ◽  
Naturally Occurring ◽  
Wheat Leaf ◽  
Wheat Leaves ◽  
Catalyzed Oxidation

Dialyzed wheat leaf extracts, catalase, and horse-radish peroxidase catalyze the decarboxylation and oxidation of indoleacetic acid at pH 5.0–6.0 in the presence of critical concentrations of manganese and monohydric phenols or resorcinol. The equivalent of 1 mole of carbon dioxide is liberated and 1 mole of oxygen consumed per mole of substrate. Manganic ions formed by a phenol–peroxidase–peroxide system initiate the decarboxylation and oxidation. A naturally occurring ether soluble factor from wheat leaves, and maleic hydrazide, can substitute for the active phenols. Catechol, hydroquinone, pyrogallol, seopoletin, and riboflavin, etc. competitively inhibit the oxidation. The nature of the active peroxide is discussed and a reaction sequence involving an organic peroxide or radical rather than hydrogen peroxide is submitted as being a possibility.

Cinétique de la formation de la métalloporphyrine Cu(II)—dérivé tétra éthylènediamino de la protoporphyrine IX (ENP) en milieu aqueux

1979 ◽  
Vol 57 (22) ◽  
pp. 2916-2922 ◽  
Author(s):  
Guy Paquette ◽  
Miklos Zador
Keyword(s):  
New Species ◽  
Reaction Kinetics ◽  
Side Chains ◽  
Mixed Complex ◽  
Final Reaction Product ◽  
Final Reaction ◽  
Kinetics Of Formation ◽  
Degree Of Association ◽  
Kinetics Of ◽  
A New Species

The kinetics of formation of the metalloporphyrin Cu(II)–ENP is dependent on the pH due to the protonation of the pyrrol nitrogen atoms and the protonation of the diamino groups of the side chains. The degree of protonation of these side chains also influences the degree of association of the prophyrin and the metalloporphyrin in solution. The order of reaction with respect to the porphyrin is not unity, a consequence of an inhibition by the reaction product; this inhibition operates via the formation of a new species, a mixed complex of porphyrin–metalloporphyrin of low reactivity.The order of reaction with respect to Cu(II) is also not unity, a consequence of the chelation of Cu(II) by the diamino groups of the side chains. The presence of Cu(II) ligands influence both the reaction kinetics and the nature of the final reaction product. [Journal translation]

THE KINETICS OF THE OXIDATION OF GASEOUS ACETALDEHYDE

1932 ◽  
Vol 7 (2) ◽  
pp. 149-161 ◽  
Author(s):  
W. H. Hatcher ◽  
E. W. R. Steacie ◽  
Frances Howland
Keyword(s):  
Carbon Dioxide ◽  
Formic Acid ◽  
Induction Period ◽  
Reaction Vessel ◽  
Oxidation Products ◽  
Main Reaction ◽  
Chain Mechanism ◽  
Subsequent Reaction ◽  
A Chain ◽  
Kinetics Of

The kinetics of the oxidation of gaseous acetaldehyde have been investigated from 60° to 120 °C. by observing the rate of pressure decrease in a system at constant volume. A considerable induction period exists, during which the main products of the reaction are carbon dioxide, water, and formic acid. The main reaction in the subsequent stages involves the formation of peroxides and their oxidation products. The heat of activation of the reaction is 8700 calories per gram molecule. The indications are that the reactions occurring during the induction period are heterogeneous. The subsequent reaction occurs by a chain mechanism. The chains are initiated at the walls of the reaction vessel, and are also largely broken at the walls.

Rheology of Thermoplastic Polyurethanes

2007 ◽  
Author(s):  
Chang Dae Han
Keyword(s):  
Rheological Behavior ◽  
Thermoplastic Polyurethane ◽  
Complete Characterization ◽  
Chain Extender ◽  
Reaction Sequence ◽  
Molecular Weights ◽  
Soft Segments ◽  
Hard Segments ◽  
A Chain ◽  
Long Chain

Thermoplastic polyurethane (TPU) has received considerable attention from both the scientific and industrial communities (Hepburn 1982; Oertel 1985; Saunders and Frish 1962). Applications for TPUs include automotive exterior body panels, medical implants such as the artificial heart, membranes, ski boots, and flexible tubing. Figure 10.1 gives a schematic that shows the architecture of TPU, consisting of hard and soft segments. Hard segments, which form a crystalline phase at service temperature, are composed of diisocyanate and short-chain diols as a chain extender, while soft segments, which control low-temperature properties, are composed of difunctional long-chain polydiols with molecular weights ranging from 500 to 5000. The soft segments form a flexible matrix between the hard domains. TPUs are synthesized by reacting difunctional long-chain diol with diisocyanate to form a prepolymer, which is then extended by a chain extender via one of two routes: (1) by a dihydric glycol chain extender or (2) by a diamine chain extender. The most commonly used diisocyanate is 4,4’-diphenylmethane diisocyanate (MDI), which reacts with a difunctional polyol forming soft segments, such as poly(tetramethylene adipate) (PTMA) or poly(oxytetramethylene) (POTM), to produce TPU, in which 1,4-butanediol (BDO) is used as a chain extender. There are two methods widely used to produce TPU: (1) one-shot reaction sequence and (2) two-stage reaction sequence. The reaction sequences for both methods are well documented in the literature (Hepburn 1982). It should be mentioned that MDI/BDO/PTMA produces ester-based TPU. One can also produce ether-based TPU when MDI reacts with POTM using BDO as a chain extender. TPUs are often referred to as “multiblock copolymers.” In order to have a better understanding of the rheological behavior of TPUs, one must first understand the relationships between the chemical structure and the morphology; thus, a complete characterization of the materials must be conducted. The rheological behavior of TPU depends, among many factors, on (1) the composition of the soft and hard segments, (2) the lengths of the soft and hard segments and the sequence length distribution, (3) anomalous linkages (branching, cross-linking), and (4) molecular weight.

scholarly journals Internalization and intracellular fate of anti-CD5 monoclonal antibody and anti-CD5 ricin A-chain immunotoxin in human leukemic T cells

Blood ◽  
1992 ◽  
Vol 79 (6) ◽  
pp. 1511-1517 ◽  
Author(s):  
S Ravel ◽  
M Colombatti ◽  
P Casellas
Keyword(s):  
Monoclonal Antibody ◽  
Direct Evidence ◽  
Intracellular Localization ◽  
Ricin A Chain ◽  
Golgi Compartment ◽  
Internalization Process ◽  
A Chain ◽  
Kinetics Of ◽  
Intracellular Fate ◽  
Ricin A

Abstract We have investigated the entry and subsequent intracellular fate of T101 monoclonal antibody (MoAb) and T101-ricin A-chain (RTA) immunotoxin (IT) directed against the CD5 antigen (Ag) expressed on human leukemic CEM cells. We provide direct evidence for the internalization of T101 MoAb and the corresponding IT. Both the MoAb and IT were internalized at a relatively low rate. This slow internalization process could be related to the partial recycling of the MoAb/Ag or IT/Ag complexes. Analysis of the internalized molecules showed that their molecular weight was only partially altered after internalization and that no free A-chain could be found inside the cells, indicating that lysosomal degradation and cleavage of disulfide- linked conjugates is a quantitatively minor phenomenon compared with the localization of internalized anti-CD5 ITs in an endosomo-Golgi compartment, followed by their recycling to the cell surface. We believe that this is the major factor explaining the low efficacy of anti-CD5 IT when assayed in the absence of potentiating substances. Finally, we showed that the presence of ammonium chloride and monensin, which both dramatically enhance the kinetics of IT activity, did not affect the rate of internalization or the intracellular localization of the conjugate, suggesting that these activators could act at the postendocytotic level on a limited number of IT molecules.

Osmium(VIII) Catalyzed Oxidation of Acetone and Ethylmethyl Ketone by Chloramine-T

1972 ◽  
Vol 27 (10) ◽  
pp. 1161-1163 ◽  
Author(s):  
S. P. Mushran ◽  
R. Sanehi ◽  
M. C. Agraval
Keyword(s):  
Acidic Medium ◽  
Present Note ◽  
Alkaline Media ◽  
Alkaline Solutions ◽  
Slow Step ◽  
First Order ◽  
Chloramine T ◽  
Kinetics Of ◽  
Catalyzed Oxidation ◽  
High Redox Potential

The Osmium (VIII) catalyzed oxidation of acetone and ethylmethyl ketone by chloramine-T, in highly alkaline solutions showed first order dependence to chloramine-T and osmium (VIII). The order of the reactions with respect to alkali and ketone were found to be fractional, being ~-0.82 and 0.3 respectively. No effects of ionic strength were evident. The mechanism has been proposed on the basis of the formation of a complex between N-chlorotoluene-p-sulfonamide and osmium (VIII) in the slow step, which in turn oxidizes the enol anion of the reducing substrate in the fast step.During the study of the mechanism of oxidations by chloramine-T, the kinetics of the oxidation of α-hydroxy acids 1 in presence of osmium (VIII) as catalyst, glycerol2 in neutral and alkaline media, p-cresol3 in an acidic medium, hexacyanoferrate (II)4 in a feebly acidic medium (pH 6-7) and aliphatic aldehydes 5 in alkaline media have been investigated.Despite the high redox potential6 of the chloramine-T/toluene sulfonamide system (1.138 V at pH 12), the oxidation of acetone does not take place in absence of catalyst and that of ethylmethyl ketone proceeds only in highly alkaline solutions7 (NaOH>0.01 M). In the present note the kinetics of the osmium (VIII) catalyzed oxidation of acetone and ethylmethyl ketone have been recorded.

scholarly journals The influence of foreign gases on the lower critical oxidation pressure of carbon disulphide

1932 ◽  
Vol 137 (833) ◽  
pp. 511-519 ◽  
Keyword(s):  
Carbon Disulphide ◽  
Chemical Change ◽  
Energy Of Activation ◽  
Unimolecular Reaction ◽  
Total Change ◽  
Chain Reactions ◽  
A Chain ◽  
Kinetics Of

The study of gaseous reactions has recently acquired additional interest, since it has been found that a considerable number of reactions can be explained on the basis of a chain hypothesis. In 1923 Christiansen and Kramers studied the kinetics of a unimolecular reaction and found that explosion is possible if the total change of energy resulting from the reaction is greater than the energy of activation. Since that time the mechanism of chain reactions has been carefully investigated and some of the conditions for the continued propagation of the reaction have been ascertained. Thus, if we have two gases mixed together without any chemical change taking place, a reaction may commence when even a very small quantity of a third molecule is added, or if one of the original molecules receives energy of activation (from whatever cause). Designating the original molecules for simplicity by A and B and the new molecule by C, which we will suppose reacts with A, giving a fourth molecule D (and possibly other molecules also), we have A + C → D.

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