scholarly journals Chemical structure and biodegradability of halogenated aromatic compounds. Substituent effects on 1,2-dioxygenation of catechol

1978 ◽  
Vol 174 (1) ◽  
pp. 85-94 ◽  
Author(s):  
E Dorn ◽  
H J Knackmuss
Keyword(s):  
Chemical Structure ◽  
Substituent Effects ◽  
Alcaligenes Eutrophus ◽  
Reaction Rates ◽  
Pseudomonas Sp ◽  
Substituent Constant ◽  
Binding Studies ◽  
Km Value ◽  
Michaelis Constants ◽  
Halogenated Aromatic Compounds

1. The influence of halogen substituents on the 1,2-dioxygenation of catechols was investigated. The results obtained with the two isoenzymes pyrocatechase I and pyrocatechase II from the haloarene-utilizing Pseudomonas sp. B 13 and the pyrocatechase from benzoate-induced cells of Alcaligenes eutrophus B.9 were compared. 2. Substituents on catechol were found to interfere with O2 binding by the two isoenzymes from Pseudomonas sp. B 13, whereas the Km value for catechol kept constant at different O2 concentrations. 3. Electron-attracting substituents decreased the Km values for catechols. 4. Results from binding studies with substituted catechols demonstrated narrow stereospecificities of pyrocatechase I from pseudomonas sp. B 13 and the pyrocatechase from alcaligenes eutrophus B.9. In contrast, a low steric hindrance by substituents in the binding of catechols with pyrocatechase II was observed. 5. Low pK′1 values of substituted catechols resulted in low Michaelis constants. 6. Electron-attracting substituents such as halogen decreased the reaction rates of catechol 1,2-dioxygenation. The correlation of the Vmax. values observed with pyrocatechase II from Pseudomonas sp. B 13 with the substituent constant sigma+ (Okamoto–Brown equation) was distinctly greater than with Hammett's sigma values. The corresponding logVmax. against sigma+ correlation for pyrocatechase I was considerably disturbed by steric influences of the substituents.

scholarly journals Chemical structure and biodegradability of halogenated aromatic compounds. Conversion of chlorinated muconic acids into maleoylacetic acid

1980 ◽  
Vol 192 (1) ◽  
pp. 339-347 ◽  
Author(s):  
E Schmidt ◽  
H J Knackmuss
Keyword(s):  
Aromatic Compounds ◽  
Chemical Structure ◽  
Pseudomonas Sp ◽  
Muconic Acid ◽  
Low Activity ◽  
Muconate Cycloisomerase ◽  
Halogenated Aromatic Compounds

1. An enzyme for the cycloisomerization of 2- and 3-chloro-cis, cis-muconic acid was isolated from 3-chlorobenzoate-grown cells of Pseudomonas sp. B13. It was named muconate cycloisomerase II, because it could it clearly be differentiated by its Km and Vmax. values from an ordinary muconate cycloisomerase, which functioned in benzoate catabolism and exhibited low activity with the chlorinated substrates. 2-Chloro-cis, cis-muconic acid was converted into trans- and 3-chloro-cis, cis–muconic acid into cis-4-carboxymethylenebut-2-en-4-olide together with dehalogenation. 2. An enzyme was isolated from chlorobenzoate-grown cells, which converted the 4-carboxymethylenebut-2-en-4-olides into maleoylacetic acid.

scholarly journals Chemical structure and biodegradability of halogenated aromatic compounds. Halogenated muconic acids as intermediates

1980 ◽  
Vol 192 (1) ◽  
pp. 331-337 ◽  
Author(s):  
E Schmidt ◽  
G Remberg ◽  
H J Knackmuss
Keyword(s):  
Chemical Structure ◽  
Acidic Solution ◽  
Pseudomonas Sp ◽  
Trans Form ◽  
Solution Ph ◽  
Muconic Acid ◽  
Acidic Solutions ◽  
Ph Conditions ◽  
Ylacetic Acid ◽  
Halogenated Aromatic Compounds

Substituted muconic acids were prepared from the corresponding catechols by pyrocatechase II from Pseudomonas sp. B13. The stabilities of substituted muconic acids were compared under different pH conditions. 3-Substituted cis, cis-muconic acids cycloisomerized readily in slightly acidic solutions, whereas 2-chloro- and 2-fluoro-cis, cis-muconic acids were stable under these conditions and could be isolated as crystalline compounds. They were isomerized to the cis, trans-form in highly acidic solution (pH 1), particularly when heated to 80 degrees C. Cycloisomerization of 2-chloro-cis, cis-muconic acid in 75% (v/v) H2SO4 yields 4-carboxymethyl-2-chloro-but-2-en-4-olide (4-chloro-2,5-dihydro-5-oxo-3H-furan-2-ylacetic acid). THe cis, cis-configuration of 2-chloromuconic acid was certified by 1H n.m.r. spectroscopy and by enzymic cycloisomerization. Although the cis, cis-configuration of 2-fluoromuconic acid was confirmed by corresponding spectroscopic data, it was not cycloisomerized by crude extracts or cycloisomerase II preparations from Pseudomonas sp. B13.

scholarly journals Chemical structure and biodegradability of halogenated aromatic compounds. Two catechol 1,2-dioxygenases from a 3-chlorobenzoate-grown pseudomonad

1978 ◽  
Vol 174 (1) ◽  
pp. 73-84 ◽  
Author(s):  
E Dorn ◽  
H J Knackmuss
Keyword(s):  
Heavy Metals ◽  
Aromatic Compounds ◽  
Chemical Structure ◽  
Specific Activity ◽  
Pseudomonas Sp ◽  
Ph Optimum ◽  
Molecular Weights ◽  
Halogenated Aromatic Compounds

1. Two catechol 1,2-dioxygenases, pyrocatechase I and pyrocatechase II, were found in 3-chlorobenzoate-grown cells of Pseudomonas sp. B 13. The latter enzyme showed high relative activities with 3- and 4-chlorocatechol compared with catechol. 2. In benzoate-grown cells, only pyrocatechase I was induced. It was purified 29-fold with a final specific activity of 20 mumol of catechol oxygenated/min per mg of protein and an overall yield of 22%. Because of the instability of pyrocatechase II on chromatography and dialysis, no increase of specific activity was obtained during the purification experiments. 3. Molecular weights of pyrocatechase I and pyrocatechase II were 82000 and 67000 respectively. 4. For both pyrocatechases the pH optimum was found to be at 8.0.5. Inhibitions of the two pyrocatechases by Cu2+ and Hg2+ ions and p-chloromercuribenzoate were different. The effect on pyrocatechase I after incubation for 20 h with the heavy metals was decreased by addition of 1 mM-2-mercaptoethanol to the reaction mixture. The inhibition of pyrocatechase II was even enhanced under these conditions. 6. Extradiol cleavage of 3-methylcatechol in addition to intradiol fission at a ratio of 1:14 was observed only with pyrocatechase I.

Chemometric Analysis of Substituent Effects. VIII. Alternative Interpretation of Substituent Effects (AISE)

1995 ◽  
Vol 60 (9) ◽  
pp. 1502-1528 ◽  
Author(s):  
Oldřich Pytela
Keyword(s):  
Multiple Bond ◽  
Substituent Effects ◽  
Alternative Interpretation ◽  
Class I ◽  
Reaction Centre ◽  
Correlation Equations ◽  
Class Iii ◽  
Substituent Constant ◽  
Chemical Models ◽  
The Individual

Alternative interpretation of substituent effects (AISE) starts from the presumption that a substituent only possesses a single property described by a single substituent constant. This property is transmitted to the reaction centre by three different ways depending on the interaction type in the triad reaction centre - basic skeleton - substituent. For interpretation it is substantial whether or not the substituent has p electrons at the atom adjacent to the basic skeleton. If it has none, the substituent belongs to class I and operates only by its basic effect described by the mentioned single substituent constant. Substituents of class II possess a free electron pair at the atom adjacent to the basic skeleton, and those of class III have a multiple bond between the first and the second atoms which is polarized in the direction from the basic skeleton. Substituent effects in class I are described by a substituent constant identical with σI constant. Substituents in classes II and III show additional effects proportional to the same constant. Hence, a separate treatment of substituent effects in the individual classes provides three straight lines intersecting in a common point. Mathematically, the description of substituent effects in this approach is expressed by a family of lines with a single explaining variable. The point of intersection, which is referred to as the iso-effect point, is not identical with the classic standard substituent - hydrogen - but is near to CN substituent. The approach given has the advantage of adopting a single substituent constant whose scale can be adjusted relatively precisely. Its drawback (like in the case of the correlation equations derived from the principle of separation of substituent effects) lies in a more extensive set of substituents needed for a correlation. The AISE principle has been applied to 318 series of experimental data describing effects of 32 substituents in a large variety of chemical models (aliphatic, alicyclic, aromatic, heteroaromatic, with or without direct conjugation between reaction centre and substituent) in both chemical reactions and equilibria. A comparison with two other correlation relations with two and three substituent constants for interpretation of substituent effects based on the principle of separation of the individual substituent effects showed that the closeness of AISE based correlations is comparable with that of the correlation equations currently used. It was somewhat less successful in the models with direct conjugation between reaction centre and substituent but the AISE principle can be used even in these cases.

Chemometric Analysis of Substituent Effects. VII. Inductive Effect as a Basic Substituent Effect. Isoeffect Substituent Constant

1995 ◽  
Vol 60 (8) ◽  
pp. 1316-1332 ◽  
Author(s):  
Oldřich Pytela ◽  
Aleš Halama
Keyword(s):  
Inductive Effect ◽  
Chemical Shifts ◽  
Quantitative Description ◽  
Substituent Effects ◽  
Intersection Point ◽  
Chemometric Analysis ◽  
Reaction Centre ◽  
Substituent Constant ◽  
Modified Method ◽  
Substituted Benzoic Acids

The paper deals with chemometric analysis of the inductive effect. The notion of inductive effect is discussed, and unambiguous definitions are given for the notions of triad: reaction centre-basic skeleton-substituent, and the therewith connected definitions of inductive effect. For a quantitative description of inductive effect 7 types of chemical models were selected including noncyclic compounds, cyclic, and bicyclic compounds, derivatives of quinuclidine, 3-substituted benzoic acids, sulfonamides and pyridines. Altogether 139 sets of experimental data from literature have been used including altogether 1 294 points (9.3 points per set, 5 points at least) reflecting substituent effects of 34 substituents. It has been found that for a standard model the dissociation of substituted bicycloalkanecarboxylic acids only is satisfactory, all the other models reflecting also the mesomeric effects to variable extent (up to 10%). A distinctly different substitution behaviour was observed with 19F and 13C NMR chemical shifts of 4-substituted 1-fluoro- or 1-methylbicyclo[2.2.2]octanes. The earlier suggested model of substituent effects based on different way of transmission of substituent effects (3 classes) has been used for separating the inductive and mesomeric effects: it is mathematically presented as a set of straight lines with the intersection point at the so-called isoeffect substituent constant. Using the modified method of conjugated deviations a chemometric scale has been created for the inductive effect which agrees very well with the conventional scales given in literature; the only differences were observed for F and CH=O substituents (which are overestimated and underestimated, respectively, in literature). In the context given the inductive effect appears as a fundamental quantity forming a basis for quantitative description of other effects transferred by electrons.

Substituent effects on polarographic reduction of some photographic color intermediates

1976 ◽  
Vol 54 (8) ◽  
pp. 1205-1210 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Bahgat E. El-Anadouli
Keyword(s):  
Dissociation Constants ◽  
Substituent Effects ◽  
Protonated Form ◽  
Acid Dissociation ◽  
Polarographic Reduction ◽  
Substituent Constant ◽  
Acid Dissociation Constants ◽  
Controlled Potential Electrolysis ◽  
Half Wave ◽  
Controlled Potential

Polarographic reduction of two series of benzoylacetanilides has been investigated in 40% (by volume) ethanolic Britton–Robinson buffers. One series (A) contains substituents on the anilide moiety, and the second (B) has substituents on both the anilide and benzoyl moieties. Polarographic controlled-potential electrolysis data indicate that the electroactive species in both series is the protonated form (ArCOCH2CONHAr′)H+. The reduction half-wave potentials of anilides of series A were found to be independent of the nature of the substituent, whereas those of series B show a good linear relationship when plotted vs. the σ substituent constant of the substituent on the benzoyl moiety (ρ = 0.284, r = 0.995). Values of the acid dissociation constants of the keto (K1) and enol (K2) tautomers of the anilides of series A were calculated; unlike their E1/2 values, the pK1 data show a linear correlation with the Hammett substituent constant, σ. The pK2 values show, however, little variation with σ.

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