scholarly journals Production of 6-Phenylacetylene Picolinic Acid from Diphenylacetylene by a Toluene-Degrading Acinetobacter Strain

2003 ◽  
Vol 69 (7) ◽  
pp. 4037-4042 ◽  
Author(s):  
Jim C. Spain ◽  
Shirley F. Nishino ◽  
Bernard Witholt ◽  
Loon-Seng Tan ◽  
Wouter A. Duetz
Keyword(s):  
Picolinic Acid ◽  
Complex Molecule ◽  
Normal Growth ◽  
Ammonium Hydroxide ◽  
Competitive Inhibitor ◽  
Growth Substrate ◽  
Oxidative Transformation ◽  
Ring Fission ◽  
Acinetobacter Strain ◽  
Picolinic Acids

ABSTRACT Several strategies for using enzymes to catalyze reactions leading to the synthesis of relatively simple substituted picolinic acids have been described. The goal of the work described here was to synthesize a more complex molecule, 6-phenylacetylene picolinic acid [6-(2-phenylethynyl)pyridine-2-carboxylic acid], for use as a potential endcapping agent for aerospace polymers. We screened 139 toluene-degrading strains that use a variety of catabolic pathways for the ability to catalyze oxidative transformation of diphenylacetylene. Acinetobacter sp. strain F4 catalyzed the overall conversion of diphenylacetylene to a yellow metabolite, which was identified as a putative meta ring fission product (2-hydroxy-8-phenyl-6-oxoocta-2,4-dien-7-ynoic acid [RFP]). The activity could be sustained by addition of toluene at a flow rate determined empirically so that the transformations were sustained in spite of the fact that toluene is a competitive inhibitor of the enzymes. The overall rate of transformation was limited by the instability of RFP. The RFP was chemically converted to 6-phenylacetylene picolinic acid by treatment with ammonium hydroxide. The results show the potential for using the normal growth substrate to provide energy and to maintain induction of the enzymes involved in biotransformation during preliminary stages of biocatalyst development.

Molecular characterization of prophenoloxidase-1 (PPO1) and the inhibitory effect of kojic acid on phenoloxidase (PO) activity and on the development ofZeugodacus tau(Walker) (Diptera: Tephritidae)

2018 ◽  
Vol 109 (2) ◽  
pp. 236-247 ◽  
Author(s):  
H.-H. Zhang ◽  
M.-J. Luo ◽  
Q.-W. Zhang ◽  
P.-M. Cai ◽  
A. Idrees ◽  
...  
Keyword(s):  
Kojic Acid ◽  
Normal Growth ◽  
Competitive Inhibitor ◽  
Inhibitory Effect ◽  
Pupal Weight ◽  
Mrna Levels ◽  
Melanin Biosynthesis ◽  
Horticultural Pest ◽  
Inhibition Experiment

AbstractPhenoloxidase (PO) plays a key role in melanin biosynthesis during insect development. Here, we isolated the 2310-bp full-length cDNA of PPO1 fromZeugodacus tau, a destructive horticultural pest. qRT-polymerase chain reaction showed that theZtPPO1transcripts were highly expressed during larval–prepupal transition and in the haemolymph. When the larvae were fed a 1.66% kojic acid (KA)-containing diet, the levels of theZtPPO1transcripts significantly increased by 2.79- and 3.39-fold in the whole larvae and cuticles, respectively, while the corresponding PO activity was significantly reduced; in addition, the larval and pupal durations were significantly prolonged; pupal weights were lowered; and abnormal phenotypes were observed. Anin vitroinhibition experiment indicated that KA was an effective competitive inhibitor of PO inZ. tau. Additionally, the functional analysis showed that 20E could significantly up-regulate the expression ofZtPPO1, induce lower pupal weight, and advance pupation. Knockdown of theZtPPO1gene by RNAi significantly decreased mRNA levels after 24 h and led to low pupation rates and incomplete pupae with abnormal phenotypes during the larval-pupal interim period. These results proved that PO is important for the normal growth ofZ. tauand that KA can disrupt the development of this pest insect.

Tripodal trisamides based on nicotinic and picolinic acid derivatives

1998 ◽  
Vol 76 (4) ◽  
pp. 414-425 ◽  
Author(s):  
H R Hoveyda ◽  
Veranja Karunaratne ◽  
Christopher J Nichols ◽  
Steven J Rettig ◽  
Ashley KW Stephens ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Metal Ion ◽  
Dissociation Constants ◽  
Picolinic Acid ◽  
Direct Methods ◽  
Acid Dissociation ◽  
Coupling Reagent ◽  
Picolinic Acids ◽  
Metal Ion Chelation ◽  
Derivatives Of

A number of polydentate arylamide ligands have been prepared by coupling various acyclic tripodal or linear polyamines with derivatives of nicotinic and picolinic acids. Two synthetic procedures were utilized; tris{[(2-hydroxynicotinyl)carbonyl]-2-aminoethyl}amine (H3NICTREN) was prepared by Method A, the HOSu/DCC method, and the other arylamides in this study were prepared by Method B, the CDI method. Method A involved the reaction of N-hydroxysuccinimide with 2-hydroxynicotinic acid (in the presence of dicyclohexylcarbodiimide (DCC) as a dehydrative coupling reagent) to form the succinimide ester, followed by reaction with TREN to yield H3NICTREN. Method B involved reaction of a carboxylic acid (2-hydroxynicotinic, 3-hydroxypicolinic, nicotinic, or picolinic acids) with carbonyldiimidazole (CDI) to form the N-acylimidazolide, followed by reaction with the amine (TREN, TAME, spermidine, or TRPN) to yield the desired arylamide. The X-ray structure of 1,1,1-tris{[(3-hydroxypicolinyl)carbonyl]-2-aminomethyl}ethane (H3PICTAME) was determined; crystals of H3PICTAME are monoclinic, a = 10.257(2), b = 15.572(3), c = 15.208(2) Å, β = 96.124(15)°, Z = 4, space group P21/a. The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.041 and Rw = 0.038 for 2506 reflections with I >= 3 sigma (I). In the solid state, H3PICTAME contains an extensive hydrogen-bonding network, with eight intra- and one intermolecular H-bonds per molecule; the ligand is partially preorganized for metal ion chelation. The acid dissociation constants of H3NICTREN and those of 1,1,1-tris{[(2-hydroxynicotinyl)carbonyl]-2- aminomethyl}ethane (H3NICTAME) have been determined; pKa1 = 11.2 (10.68), pKa2 = 10.7 (10.58), pKa3 = 10.0 (9.71), and pKa4 = 6.25 for H3NICTREN (H3NICTAME); the high phenolic pKa's are consistent with the hydrogen bonding observed in the solid state.Key words: arylamide, hydrogen bonding, preorganization.

scholarly journals Bacterial metabolism of 5-aminosalicylic acid. Initial ring cleavage

1992 ◽  
Vol 282 (3) ◽  
pp. 675-680 ◽  
Author(s):  
A Stolz ◽  
B Nörtemann ◽  
H J Knackmuss
Keyword(s):  
Bacterial Metabolism ◽  
Ring Cleavage ◽  
Pseudomonas Sp ◽  
Growth Substrate ◽  
Aminosalicylic Acid ◽  
Intact Cells ◽  
Cell Extracts ◽  
Ring Fission ◽  
Stoichiometric Reaction ◽  
Neutral Conditions

The metabolism of 5-aminosalicylate (5AS) by a bacterial strain, Pseudomonas sp. BN9, was studied. Intact cells of Pseudomonas sp. BN9 grown with 5AS oxidized 5AS and 2,5-dihydroxybenzoate (gentisate), whereas cells grown with gentisate oxidized only the growth substrate of all substituted salicylates tested. Cell extracts from Pseudomonas sp. BN9 catalysed the stoichiometric reaction of 1 mol of oxygen with 1 mol of 5AS to a metabolite with an intense u.v.-absorption maximum at 352 nm (pH 8.0). This metabolite was accumulated under neutral conditions, but was rapidly destroyed at acid pH. It was identified by m.s. and acid-catalysed deamination to fumarylpyruvate (trans-2,4-dioxohept-5-enedioic acid) as cis-4-amino-6-carboxy-2-oxohexa-3,5-dienoate, thus demonstrating direct cleavage of the monohydroxylated substrate 5AS to a non-aromatic ring-fission product. The enzyme responsible for conversion of 5AS was shown to be Fe(II)-dependent and to be distinct from gentisate 1,2-dioxygenase in strain BN9.

scholarly journals Inhibitor and substrate cooperate to inhibit amyloid fibril elongation of α-synuclein

2020 ◽  
Vol 11 (41) ◽  
pp. 11331-11337 ◽  
Author(s):  
Emil Dandanell Agerschou ◽  
Vera Borgmann ◽  
Michael M. Wördehoff ◽  
Wolfgang Hoyer
Keyword(s):  
Amyloid Fibril ◽  
Competitive Inhibitor ◽  
Dual Role ◽  
Growth Substrate

Amyloid fibril elongation of α-synuclein can be described with the Michaelis–Menten model, where α-synuclein monomer plays a dual role by serving as growth substrate as well as supporting the competitive inhibitor CC48 in blocking fibril ends.

Kinetics and mechanism of decarboxylation of some pyridinecarboxylic acids in aqueous solution. II

1977 ◽  
Vol 55 (8) ◽  
pp. 1342-1347 ◽  
Author(s):  
Gerald E. Dunn ◽  
Harald F. Thimm
Keyword(s):  
Lower Energy ◽  
Picolinic Acid ◽  
Critical Role ◽  
Bond Breaking ◽  
Carboxyl Group ◽  
Carboxylate Oxygen ◽  
Carbon Carbon Bond ◽  
Nitrogen Hydrogen Bond ◽  
Picolinic Acids ◽  
Pyridinecarboxylic Acids

Six 3-substituted picolinic acids were synthesized and decarboxylated in buffered aqueous solutions of ionic strength 1.0 at 150 and/or 95 °C. 3-Amino- and 3-hydroxypicolinic acids appear to decarboxylate by initial protonation, but the others fit the requirements of the Hammick mechanism for picolinic acid decarboxylation. Both electron-withdrawing and electron-releasing 3-substituents accelerate decarboxylation in picolinic acids but inhibit decarboxylation in their anions. Acceleration in the acids is considered to be the result of interference by 3-substituents with coplanarity of the carboxyl group and the aromatic nucleus. This reduces the order of the bond between the carboxyl group and the ring, thus facilitating bond breaking. In decarboxylation of the anions water appears to play a critical role, since picolinate ions have not been observed to decarboxylate in any other solvent, including ethylene glycol. It is proposed that water forms a hydrogen-bonded bridge between carboxylate oxygen and aromatic nitrogen, so that as the carbon–carbon bond breaks a nitrogen–hydrogen bond is formed. This may provide a lower energy path through an ylide intermediate than would be required if the picolinate ion were to decarboxylate to a 2-pyridyl carbanion.

Effect of competition from other metals on nickel complexation by α-isosaccharinic, gluconic and picolinic acids

2012 ◽  
Vol 76 (8) ◽  
pp. 3425-3434 ◽  
Author(s):  
N. D. M. Evans ◽  
S. Antón Gascón ◽  
S. Vines ◽  
M. Felipe-Sotelo
Keyword(s):  
Metal Ions ◽  
Gluconic Acid ◽  
Solid Phase ◽  
Picolinic Acid ◽  
Competition Effects ◽  
Solid Phases ◽  
The Many ◽  
Picolinic Acids ◽  
Isosaccharinic Acid ◽  
Competing Ions

AbstractThe effect of competition from other metal ions on the complexation of Ni with isosaccharinic acid, gluconic acid and picolinic acid, at high pH, is described. The competing metal ions used were divalent Co, trivalent Eu and tetravalent Th. In the majority of cases, competition from these metal ions followed the predicted pattern, with most anomalies seeming to be caused by sorption of Ni to the many different solid phases formed in presence of the competing ions. The Ni solid phase was shown to change with time during the course of the study. No major unexplained competition effects were found.

Kinetics and mechanism of decarboxylation of some pyridinecarboxylic acids in aqueous solution. III. 3-Hydroxy- and 3-aminopyridine-2-carboxylic acids

1979 ◽  
Vol 57 (9) ◽  
pp. 1098-1104 ◽  
Author(s):  
Gerald E. Dunn ◽  
Harald F. Thimm ◽  
Rajani K. Mohanty
Keyword(s):  
Aqueous Solution ◽  
Isoelectric Point ◽  
Rate Constants ◽  
Picolinic Acid ◽  
Kinetic Isotope ◽  
Rate Maximum ◽  
Anthranilic Acids ◽  
Rate Profile ◽  
Picolinic Acids ◽  
Pyridinecarboxylic Acids

Pseudo-first-order rate constants for the decarboxylation of 3-hydroxy- and 3-amino- picolinic acids in aqueous solution at 150 °C were determined and plotted as a function of acidity. Each rate profile has a maximum at an acidity well above the isoelectric point and this is attributed to decarboxylation of an intermediate protonated at the 2-position, analogous to the intermediates involved in the decarboxylation of salicylic and anthranilic acids. There is also a shoulder on each rate profile at a lower acidity corresponding to the isoelectric point where the Hammick ylide mechanism has a rate maximum in most picolinic acid decarboxylations. It is concluded that 3-hydroxy- and 3-aminopicolinic acids decarboxylate by the ylide mechanism at low acidity and by the protonation mechanism at higher acidities. In agreement with this interpretation, the 13C kinetic isotope effect in 3-hydroxypicolinic acid decarboxylation is 2.0% on the ylide part of the curve, 1.3% where decarboxylation of the protonated intermediate is rate determining, and drops to 0.4% in the intermediate region. Comparison of the rate constants for ylide decarboxylation with those for other 3-substituted picolinic acids shows that 3-hydroxy and 3-amino substituents facilitate decarboxylation, probably by their inductive and field effects on the developing negative charge at the 2-position of the transition state.

Kinetics and Mechanism of Decarboxylation of some Pyridinecarboxylic Acids in Aqueous Solution

1972 ◽  
Vol 50 (18) ◽  
pp. 3017-3027 ◽  
Author(s):  
G. E. Dunn ◽  
Gordon K. J. Lee ◽  
Harold Thimm
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Exchange ◽  
Picolinic Acid ◽  
Substituent Effects ◽  
Kinetic Isotope ◽  
Rate Maximum ◽  
Isoelectric Ph ◽  
Picolinic Acids ◽  
Carboxyl Carbon ◽  
Pyridinecarboxylic Acids

The first-order rate constants for decarboxylation of picolinic and five substituted picolinic acids in buffered aqueous solution at 150° and ionic strength 1.0 increase as pH increases above 0, go through a maximum at pH near 1, then level off at about half the maximum. For quinolinic acid at 95° the rate maximum occurs at the isoelectric pH. It is therefore concluded that the anion decarboxylates about half as fast as the isoelectric species. Anion and isoelectric species show similar carboxyl-carbon kinetic isotope and substituent effects, so they probably decarboxylate by similar mechanisms. The methyl betaine of picolinic acid decarboxylates about 200 times faster than the anion. From these facts it is concluded that the isoelectric species which decarboxylates is probably zwitterion rather than neutral acid, and that anion and zwitterion decarboxylate by loss of carbon dioxide to form 2-pyridyl carbanion and ylid, respectively. The slower decarboxylation of isoelectric species compared to betaine suggests that only a small fraction of the isoelectric species is zwitterion. However, qualitative estimates from spectra of the fraction of zwitterion present in the isoelectric species at 150° suggest that this cannot be the whole explanation. The relative reactivities of the 2-and 4-positions are similar for decarboxylation and hydrogen exchange in pyridinium ions, but not in the unprotonated species.

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