Rapidreaction between unifunctional molecules and molecules unifunctional at one position and n-functional at another

1957 ◽  
Vol 10 (2) ◽  
pp. 99 ◽  
Author(s):  
HG Higgins
Keyword(s):  
The Other ◽  
Rate Equations ◽  
Amino Group

Rate equations for the reaction between A and B, where B is unifunctional, and A is unifunctional at one and n-functional at the other of two independent positions, lead to expressions for the final relative concentrations of the reactants and products in terms of the initial concentrations of A and B, the ratio of the velocity constants at the two positions on A, and the functionality n. These results are applied to the reaction of tryptophane with p-diazobenzenesulphonic acid, in which it appears that the indole group reacts somewhat faster than the amino group.

A polycentric growth model of gallium arsenide epitaxial layers from the gas phase with simultaneous diffusion, adsorption and chemical reaction

1988 ◽  
Vol 53 (12) ◽  
pp. 2995-3013
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Surface Reaction ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Impact Interaction ◽  
Partial Pressures

For a quantitative description of the epitaxial growth rate of gallium arsenide, two models are proposed including two rate controlling steps, namely the diffusion of components in the gas phase and the surface reaction. In the models considered, the surface reaction involves a reaction triple - or quadruple centre. In both models three mechanisms are considered which differ one from the other by different adsorption - and impact interaction of reacting particles. In every of the six cases, the pertinent rate equations were derived, and the models have been confronted with the experimentally found dependences of the growth rate on partial pressures of components in the feed. The results are discussed with regard to the plausibility of individual mechanisms and of both models, and also with respect to their applicability and the direction of further investigations.

Two ubiquitin-like conjugation systems that mediate membrane formation during autophagy

2013 ◽  
Vol 55 ◽  
pp. 39-50 ◽  
Author(s):  
Hitoshi Nakatogawa
Keyword(s):  
Light Chain ◽  
Membrane Dynamics ◽  
The Other ◽  
Aminobutyric Acid ◽  
Amino Group ◽  
Autophagosome Formation ◽  
Acid Receptor ◽  
Receptor Associated Protein ◽  
Atg Proteins ◽  
C Terminus

In autophagy, the autophagosome, a transient organelle specialized for the sequestration and lysosomal or vacuolar transport of cellular constituents, is formed via unique membrane dynamics. This process requires concerted actions of a distinctive set of proteins named Atg (autophagy-related). Atg proteins include two ubiquitin-like proteins, Atg12 and Atg8 [LC3 (light-chain 3) and GABARAP (γ-aminobutyric acid receptor-associated protein) in mammals]. Sequential reactions by the E1 enzyme Atg7 and the E2 enzyme Atg10 conjugate Atg12 to the lysine residue in Atg5, and the resulting Atg12–Atg5 conjugate forms a complex with Atg16. On the other hand, Atg8 is first processed at the C-terminus by Atg4, which is related to ubiquitin-processing/deconjugating enzymes. Atg8 is then activated by Atg7 (shared with Atg12) and, via the E2 enzyme Atg3, finally conjugated to the amino group of the lipid PE (phosphatidylethanolamine). The Atg12–Atg5–Atg16 complex acts as an E3 enzyme for the conjugation reaction of Atg8; it enhances the E2 activity of Atg3 and specifies the site of Atg8–PE production to be autophagy-related membranes. Atg8–PE is suggested to be involved in autophagosome formation at multiple steps, including membrane expansion and closure. Moreover, Atg4 cleaves Atg8–PE to liberate Atg8 from membranes for reuse, and this reaction can also regulate autophagosome formation. Thus these two ubiquitin-like systems are intimately involved in driving the biogenesis of the autophagosomal membrane.

THE METABOLISM OF PUTRESCINE (1,4-DIAMINOBUTANE) BY MYCOBACTERIA ISOLATED FROM FISH: II. STUDIES WITH ARSENITE-INHIBITED CELLS AND CELL-FREE EXTRACTS

1967 ◽  
Vol 13 (5) ◽  
pp. 521-531 ◽  
Author(s):  
T. P. T. Evelyn
Keyword(s):  
Succinic Acid ◽  
Tricarboxylic Acid Cycle ◽  
Significant Proportion ◽  
Tricarboxylic Acid ◽  
The Other ◽  
Aminobutyric Acid ◽  
Succinic Semialdehyde ◽  
Amino Group ◽  
Intact Cells ◽  
Acid Cycle

Three mycobacterial strains isolated from fish degraded putrescine by a pathway in which γ-aminobutyraldehyde (Δ′-pyrroline), γ-aminobutyric acid, succinic semialdehyde, and succinic acid were intermediates. These results agree substantially with those of other workers using different microorganisms. Intact cells utilized γ-aminobutyric acid in a transaminase reaction with endogenously supplied α-ketoglutarate to produce succinic semialdehyde and glutamate. Studies with arsenite-poisoned cells showed that a significant proportion of putrescine was metabolized via pyruvate and alanine. When putrescine-1,4-14C was substrate, HCl extracts of cells contained radioactive aspartate and glutamate in addition to alanine. The further metabolism of succinate therefore proceeded in two directions: one yielding oxalacetate and α-ketoglutarate by way of the tricarboxylic acid cycle, and the other branching off the cycle to yield pyruvate. Studies with cell-free extracts suggested that putrescine nitrogen was assimilated via glutamate, which served as the amino-group donor to yield alanine and aspartate.

scholarly journals The antiseptic and trypanocidal action of certain styryl and anil quinoline carboxylamides.*

1932 ◽  
Vol 110 (767) ◽  
pp. 249-260
Keyword(s):  
Amide Group ◽  
The Other ◽  
Amino Group ◽  
Active Compounds ◽  
Basic Group ◽  
Urethane Group ◽  
Highly Active ◽  
Quaternary Compounds ◽  
Quinoline Series

In the case of quaternary compounds of the styryl quinoline series and of the analogous benzthiazole derivatives a powerful trypanocidal effect in vivo has been shown to depend on the presence in the substance of a free basic group in one of the nuclei, and anacylamino (especially acetyl) or urethane group in the other, and also on the styryl linkage—each playing a definite part in contributing to the action (Browning, Cohen, Ellingworth and Gulbransen, 1929, 1931). This is exemplified by 2( p -aminostyryl)-6 acetylamino quinoline methochloride (No. 8), 2( p -dimethylamino styryl)-6 acetylamino quinoline methochloride (No. 25), 2( p -acetylamino)-6 dimethylamino quinoline methochloride (No. 90) and 2( p -dimethylamino styryl) quinolyl (6) urethane (Me) methochloride (No. 125). The effect of acetylation of the amino group parallels that dis­covered by Ehrlich and his co-workers in the case of p -amino phenyl arsinic acid. Gough and King (1930) have recently made the important observation that in the latter series the introduction of an amide group converts the therapeutically inactive carboxylic and sulphonic acids into active compounds. Accordingly, the effect of substituting a carboxylamide group for the acylamino in compounds of the type of No. 25 and its anil analogue (No. 62) has been investigated. In addition, the position of the carboxylamide group has been varied. These substances were further examined for antiseptic action, the results being shown in the table. Trypanocidal properties have been tested on T. brucei infections in mice as in previous work. The striking observation has been made that only those compounds with the carboxylamide group in the 6 position are therapeutically active, the anils being only slightly less effective than the styryl analogues ( cf . Nos. 410, 409 and 385, 403). This contrasts with what is found in the acetylamino derivatives, since the styryl compounds of the latter are highly active as compared with the corresponding anils. The carboxy-ethylamides (420, 419) are more toxic and less trypanocidal than the corresponding amides and methylamides.

scholarly journals Crystal structure of dichlorido{4-[(E)-(methoxyimino-κN)methyl]-1,3-thiazol-2-amine-κN3}palladium(II)

2015 ◽  
Vol 71 (1) ◽  
pp. m10-m11 ◽  
Author(s):  
Viktorita V. Dyakonenko ◽  
Olga O. Zholob ◽  
Svitlana I. Orysyk ◽  
Vasily I. Pekhnyo
Keyword(s):  
Bidentate Ligand ◽  
The Other ◽  
Mean Deviation ◽  
Amino Group ◽  
Methyl Group ◽  
Square Planar ◽  
The Mean ◽  
Van Der Waals Radii ◽  
Cl Atoms ◽  
Coordination Plane

In the title compound, [PdCl2(C5H7N3OS)], the PdIIatom adopts a distorted square-planar coordination sphere defined by two N atoms of the bidentate ligand and two Cl atoms. The mean deviation from the coordination plane is 0.029 Å. The methyl group is not coplanar with the plane of the metallacycle [torsion angle C—O—N—C = 20.2 (4)°]. Steric repulsion between the methyl group and atoms of the metallacycle is manifested by shortened intramolecular H...C contacts of 2.27, 2.38 and 2.64 Å, as compared with the sum of the van der Waals radii of 2.87 Å. The amino group participatesviaone H atom in the formation of an intramolecular N—H...Cl hydrogen bond. In the crystal, the other H atom of the amino group links moleculesviabifurcated N—H...(Cl,O) hydrogen bonds into chains parallel to [001].

Kinetics of rapid reactions involving two pairs of consecutive second order steps

1953 ◽  
Vol 6 (3) ◽  
pp. 195 ◽  
Author(s):  
HG Higgins ◽  
EJ Williams
Keyword(s):  
Molecular Structure ◽  
Second Order ◽  
The Other ◽  
Rate Equations ◽  
Special Cases ◽  
Kinetics Of ◽  
Initial Reactivity

An examination is made of the kinetics of the reaction between A and B, where both reactants are capable of unifunctional behaviour, and A is also capable of bifunctional behaviour, for the general case in which the two reactive sites on A are not equivalent. Solutions are given of the appropriate rate equations for the two pairs of consecutive stages, and it is shown that the final concentrations of reactants and products can be related to given values of the initial concentrations and the velocity constants of the four second order stages. Relatively simple relations are established between the final concentrations and the ratio of the velocity constants for the case in which reaction at one position on A does not affect the reactivity of the other position. Some special cases of interest are considered. The results are related to the authors' earlier treatment of the case In which the initial reactivity of the two positions on A is initially the same. The theory is applied, by way of example, to the coupling of histidine with p-diazobenzenesulphonic acid, which appears to conform to the assumption of the same initial reactivity. The implications of the method in the correlation of molecular structure and reactivity are briefly discussed.

scholarly journals Purification of the glycoprotein lectin from the broad bean (Vicia faba) and a comparison of its properties with lectins of similar specificity

1976 ◽  
Vol 155 (1) ◽  
pp. 127-135 ◽  
Author(s):  
A K Allen ◽  
N N Desai ◽  
A Neuberger
Keyword(s):  
Affinity Chromatography ◽  
Vicia Faba ◽  
Acid Derivative ◽  
Concanavalin A ◽  
Broad Bean ◽  
Soya Bean ◽  
Hexanoic Acid ◽  
The Other ◽  
Amino Group ◽  
Strong Inhibition

1. The lectin from the broad bean (Vicia faba) was purified by affinity chromatography by using 3-O-methylglucosamine covalently attached through the amino group to CH-Sepharose (an omega-hexanoic acid derivative of agarose). Its composition and the nature of its subunits were compared with concanavalin A and the lectins from pea and lentil. 2. Unlike the other three lectins, broad-bean lectin is a glycoprotein; a glycopeptide containing glucosamine and mannose was isolated from a proteolytic digest. 3. The mol.wt. is about 47500; the glycoprotein consists of two apprently identical subunits, held together by non-covalent forces. Fragments of the subunits, similar to those found in concanavalin A and soya-bean agglutinin, were found in active preparations. 4. Broad-bean lectin was compared with concanavalin A and the lectins from pea and lentil in an investigation of the inhibition of their action by a number of monosaccharides, methyl ethers of monosaccharides, disaccharides and glycopeptides. The most striking differences concern 3-O-substituted monosaccharides, which are strong inhibitors of the action of broad-bean, pea and lentil lectins but not of the action of concanavalin A. There is, however, no strong inhibition of the action of these lectins by 3-Olinked disaccharides.

scholarly journals Sources of ammonia for mammalian urea synthesis

1978 ◽  
Vol 176 (3) ◽  
pp. 733-737 ◽  
Author(s):  
H A Krebs ◽  
R Hems ◽  
P Lund ◽  
D Halliday ◽  
W W Read
Keyword(s):  
Glutamate Dehydrogenase ◽  
Initial Rate ◽  
Adenine Nucleotides ◽  
Rat Hepatocytes ◽  
The Other ◽  
Amino Group ◽  
Urea Synthesis ◽  
Purine Nucleotide ◽  
Carbamoyl Phosphate ◽  
Purine Nucleotide Cycle

The initial rate of incorporation of [15N]alanine into the 6-amino group of the adenine nucleotides in rat hepatocytes was about one-eighteenth of the rate of incorporation into urea. Thus the purine nucleotide cycle cannot provide most of the ammonia needed in urea synthesis for the carbamoyl phosphate synthase reaction (EC 2.7.2.5). On the other hand, contrary to the view expressed by McGivan & Chappell [(1975) FEBS Lett. 52, 1–7], the experiments support the view that hepatic glutamate dehydrogenase can supply the required ammonia.

ANNOTININE: THE REACTIONS OF THE CYCLIC ETHER FUNCTION

1954 ◽  
Vol 32 (3) ◽  
pp. 268-279 ◽  
Author(s):  
H. L. Meier ◽  
P. D. Meister ◽  
Léo Marion
Keyword(s):  
Chromic Acid ◽  
Cyclic Ether ◽  
The Other ◽  
Amino Group ◽  
Imino Group ◽  
Unsaturated Lactone ◽  
Clemmensen Reduction ◽  
Secondary Amino ◽  
Concentrated Solution ◽  
Chromous Chloride

Treatment of annotinine chlorohydrin with chromous chloride has been found to produce not only the already reported unsaturated lactone A (C16H21O2N), but also a second unsaturated lactone B (C16H21(23)O2N), and a hydroxylactone (C16H23O3N). Under the action of a concentrated solution of the same reagent the hydroxylactone is converted to the unsaturated lactone B. On hydrogenation the latter gives a dihydrolactone B which seems to contain a secondary amino group. Annotinine hydrate on treatment with thionyl chloride gives an unsaturated chlorolactone (C16H20O2NCl) which can be hydrogenated and subsequently dechlorinated to produce a third lactone C, different from either of dihydrolactones A or B, but which like the latter seems to contain an imino group. Oxidation of annotinine hydrate with chromic acid produces a hydroxyketone which can be converted into an oxime and, therefore, one of the hydroxyls of the hydrate is secondary while the other is probably tertiary. On the other hand, oxidation of annotinine with potassium permanganate gives rise to a lactam which by the Clemmensen reduction is converted to a mixture of lactam chlorohydrin and dihydrolactone A.

scholarly journals Studies on the mechanism and kinetics of the 2-oxoglutarate dehydrogenase system from pig heart

1977 ◽  
Vol 161 (3) ◽  
pp. 569-581 ◽  
Author(s):  
C L McMinn ◽  
J H Ottaway
Keyword(s):  
Initial Rate ◽  
Optimization Technique ◽  
Random Order ◽  
The Other ◽  
Rate Equations ◽  
Kinetic Properties ◽  
Ping Pong ◽  
System 2 ◽  
Dehydrogenase System ◽  
Oxoglutarate Dehydrogenase

1. The kinetic properties of the 2-oxoglutarate dehydrogenase system were investigated. To this end, initial-velocity studies were carried out by the method of Fromm [(1967) Biochim. Biophys. Acta 139, 221-230]. Reciprocal plots of the results did not agree with those expected for the Hexa Uni Ping Pong mechanism previously proposed for the system. 2. The measured initial velocities were fitted to initial-rate equations corresponding to several possible mechanisms by using a computer optimization technique. Statistical analyses performed on the results of the optimization studies indicated that one mechanism was a significantly better fit to the experimental data than the other mechanisms tested. This mechanism is one in which there is a random order of binding of NAD+ and CoA and release of succinyl-CoA, although the binding of 2-oxoglutarate and release of CO2 is still given a Ping Pong mechanism, which precedes the binding of the other substrates. These conclusions were supported by NADH-inhibition studies. 3. The usefulness of the method of fitting initial-rate data to rate equations and the applicability of the proposed enzymic mechanism to the enzyme complex are discussed.

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