Presence Of Ammonium Ions Research Articles

Reaction Investigation of Metal Salts with Tetrakis(hydroxymethyl)phosphonium Sulfate and Chloride

The interaction of tetrakis(hydroxymethyl)phosphonium sulfate (THPS) and chloride (THPC) with water-soluble and water-insoluble metal compounds was investigated. We evaluated solutions of the phosphonium salts for dissolution of metal sulfides, and complexation of the THP moiety with Fe2+, Fe3+, Cu2+, Zn2+, Hg2+, and Pb2+. Scanning ultraviolet/visible spectroscopy was deployed to monitor complex formation. Applying mole ratios of 1–9 THP:1 M n+ (Fe3+, Hg2+, and Pb2+) revealed the formation of several complexes. THP did not appear to complex with Fe2+ and Zn+2 although isobestic points were maintained in the UV spectra. The results of this investigation did not confirm prior studies that showed complexation of Fe2+ with THP in the presence of ammonium ion. Results suggest that THPS and THPC dissolved metal sulfide precipitates at mildly acidic conditions, and THP often formed stable complexes of variable stoichiometry with the metal cations.

Influence of the concentrations of potassium, sodium, and ammonium ions on the cesium sorption with mixed nickel potassium ferrocyanide sorbent based on hydrated titanium dioxide

The effect of single-charged cations (Na+, K+, NH +4 ) on the cesium sorption with mixed nickel potassium ferrocyanide sorbent based on hydrated TiO2 was studied. The K+ and Na+ ions exert no effect at their concentrations of up to 0.5 M; the Cs+ distribution coefficients from KCl and NaCl solutions are (1.1 ± 0.5) × 105 and (8 ± 3) × 104 mL g−1, respectively. The sorbent is highly specific to Cs+ in the presence of ammonium ions. The sorption mechanisms were studied. The concentration ranges in which Cs+ and NH +4 are sorbed by independent mechanisms (Cs+, by the ferrocyanide phase; NH +4 , by the phase of hydrated TiO2) and in which the Cs+ distribution coefficient decreases owing to competitive filling of the ferrocyanide phase with ammonium ions were determined. At cesium concentrations in solution exceeding 50 mg L−1, Cs+ and NH +4 are absorbed jointly owing to coprecipitation in the mixed ferrocyanide phase in the pore space of the sorbent.

Nanozeolites: New strategies for designing ultra small silicalite crystals with very few framework defects

Framework defect-free nanosized silicalite-1 crystals (ca. 150nm) have been obtained by post-synthesis modification of a zeolite prepared under alkaline pH conditions. Several methods have been proposed, all of them being based on dissolution/recrystallization processes that keep the size of the zeolite crystals unchanged. Treatment of as-made zeolites with NH4F led to a significant decrease in the density of siloxy framework defects but silanol groups could not be totally eliminated, even after calcination. On the other hand, a succession of treatments in TPAOH and NH4F led to materials with very few framework defects and more or less regular hollow structures. The best solids were obtained when treatments were performed on calcined zeolites with solid NH4F. Under such conditions, zeolites were first dissolved following a mechanism similar to that observed under alkaline pH conditions but hollow structures thus obtained could not be stabilized and they progressively disappeared with time. Despite that, the crystallinity remained unaltered and treated zeolites were characterized by highly resolved 29Si NMR spectra, characteristic of defect-free all-silica frameworks. Modifications of the crystal shape with time have been explained by a partial recrystallization of the zeolite in the presence of ammonium ions.

A comparative study of ORR at the Pt electrode in ammonium ion-contaminated H2SO4 and HClO4 solutions

Poisoning of the poly-Pt electrode by low concentration ammonium ion was investigated in H2SO4 and HClO4 solutions and a significant poisoning was observed in H2SO4 solution. An extraordinary recovery of the poisoned electrode was achieved in HClO4 solution by cycling the electrode potential between the onset potentials of the hydrogen and oxygen evolution. The extent of recovery was marked using the oxygen reduction reaction (ORR) as a probing reaction. Ammonium ion poisoning of the electrodes in H2SO4 caused a significant contribution of the two-electron reduction of O2 to hydrogen peroxide, as indicated by the rotating ring-disk voltammetry. The Tafel slopes at the low and high current densities were also affected by the presence of ammonium ion in H2SO4 solution and an increase in the Tafel slope was recognized with increasing the concentration of ammonium ion. However, the Tafel slopes at the low and high current densities were hardly affected by the ammonium ion in HClO4 solution.

Amelioration of photofermentative hydrogen production from molasses dark fermenter effluent by zeolite-based removal of ammonium ion

One of the challenges in the development of integrated dark and photofermentative biological hydrogen production systems is the presence of ammonium ions in dark fermentation effluent (DFE). Ammonium strongly inhibits the sequential photofermentation process, and so its removal is required for successful process integration. In this study, the removal of ammonium ions from molasses DFE using a natural zeolite (clinoptilolite) was investigated. The samples were treated with batch suspensions of Na-form clinoptilolite. The ammonium ion concentration could be reduced from 7.60 mM to 1.60 mM and from 12.30 mM to 2.40 mM for two different samples. Photofermentative hydrogen production on treated and untreated molasses DFE samples were investigated in batch photobioreactors by an uptake hydrogenase deleted (hup−) mutant strain of Rhodobacter capsulatus. Maximum hydrogen productivities of 1.11 mmol H2/Lc·h and 1.16 mmol H2/Lc·h and molar yields of 79% and 90% were attained in the treated DFE samples, while the untreated samples resulted in no hydrogen production. The results showed that ammonium ions in molasses DFE could be effectively removed using clinoptilolite by applying a cost-effective, simple batch process.

Incorporation of 15N-Labeled Ammonia into Glutamine Amide Groups by Protein-Glutaminase and Analysis of the Reactivity for α-Lactalbumin

Protein-glutaminase (PG) is an enzyme that catalyzes the deamidation of protein-bound glutamine residues. We found that an enzyme labeling technique (ELT), which is a stable isotope labeling method based on transglutaminase (TGase) reaction, is applicable for PG. PG catalyzed incorporation of (15)N-labeled ammonium ions into reactive glutamine amide groups in α-lactalbumin similarly to TGase and deamidated the most reactive glutamine amide group once labeled with (15)N. Furthermore, we investigated the effect of ammonium ions on the PG activity by peptide mapping, and more reactive glutamine residues were detected than were detected by the ELT in the presence of ammonium ions. This is probably because ammonium ions are competitive inhibitors, causing decreased reactivity for glutamine residues. We propose the reaction scheme of PG in the presence of the (15)N-labeled ammonium ions and show that the ELT method with PG is useful for evaluating the activity of PG.

Effects of nitrogen sources on production and composition of sophorolipids by Wickerhamiella domercqiae var. sophorolipid CGMCC 1576

The effects of nitrogen sources on growth of sophorolipid-producing yeast, Wickerhamiella domercqiae var. sophorolipid CGMCC 1576 and on production and composition of sophorolipids were studied. Organic nitrogen sources are more favorable for accumulation of biomass than inorganic ones. Presence of ammonium ion from different inorganic nitrogen sources (except NH(4)HCO(3)) greatly inhibited the production of lactonic sophorolipids. However, when organic nitrogen sources were used, lactonic sophorolipid production was strongly increased. Production of crystalline lactonic sophorolipids from organic/inorganic nitrogen sources was enhanced with the increase of pH value adjusted by sodium hydroxide or sodium citrate solution. Fourier-transform infrared (FT-IR), gas chromatography mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), and mass spectra (MS) were employed to compare the composition of sophorolipid mixture obtained from different nitrogen sources. More than 15 acidic sophorolipid molecules and only 4 lactonic sophorolipid molecules were produced by using 1.27 g/l ammonium sulfate as nitrogen source; they were separated by preparative HPLC and their structures were elucidated by MS. These results suggest extraordinary regulatory effects of nitrogen source on growth and sophorolipid synthesis of W. domercqiae var. sophorolipid.

NH 4-smectite: Characterization, hydration properties and hydro mechanical behaviour

Leachates in waste landfills are characterized by the presence of ammonium ions in large excess. These ammonium ions can be exchanged with the interlayer cations in clay and modify the physical and chemical properties of clay geochemical barriers in waste landfills and drive to environmental problems. The purpose of this study was to understand the hydro-physical changes of a smectite in the presence of ammonium ions. An ammonium smectite was prepared by cation exchange from a natural montmorillonite (Wyoming). The samples were characterized and their properties were compared by the use of a set of complementary techniques (X-ray diffraction, infrared spectroscopy, N 2 adsorption–desorption BET technique, thermal analysis, and percolation experiments). The main effect was a modification of the porosity and its network, and reduced crystalline swelling. These effects changed the hydraulic conductivity and macroscopic swelling of the clay. The oedometer experiments, which allow simulating the pressure on small amounts of samples, proved the strong increase of the permeability of NH 4-smectite. This last point is of great importance in an environment point of view and raises questions on the impermeability behaviour on the long term of the clay geochemical barriers with the presence of ammonium ions in waste landfills.

Interaction of hypochlorous acid and myeloperoxidase with phosphatidylserine in the presence of ammonium ions

The close association of the heme enzyme myeloperoxidase to phosphatidylserine epitopes on the surface of non-vital polymorphonuclear leukocytes (PMNs) and other apoptotic cells at inflammatory sites favours modifications of this phospholipid by myeloperoxidase products. As detected by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, ammonium ions inhibit in a concentration-dependent manner the hypochlorous acid-mediated formation of aldehyde and nitrile products from 1,2-dipalmitoyl- sn-glycero-3-phosphoserine (DPPS). Concomitantly, the formation of monochloramine (NH 2Cl) raises with increasing NH 4 + concentrations. A transchlorination from monochlorinated O-phospho- l-serine to NH 4 + with the formation of NH 2Cl occurs only when extraordinary high NH 4 + concentrations are applied. Due to the low rate of 0.044 M − 1 s − 1 for this process, a transhalogenation reaction from transient chlorinated intermediates of the serine moiety to NH 4 + can be ruled out as an important process contributing to the HOCl-mediated formation of NH 2Cl. A significant formation of NH 2Cl by myeloperoxidase interacting with DPPS in the presence of ammonium ions takes only place at acidic pH values around 5, a scenario that may occur in phagosomes of macrophages after the uptake of apoptotic PMNs.

A Biotin-Coupled Bifunctional Enzyme Exhibiting Both Glutamine Synthetase Activity and Glutamate Decarboxylase Activity

Purpose: To purify and study native form and enzymatic activity of the 42 kDa biotin-coupled protein (p42), which is related to glutamate action in chick retina.Methods: p42 was purified using molecular filtration in the presence of 0.7 M sodium chloride. Purity and identification of p42 were studied by SDS-PAGE, 2D-PAGE, LC-MS/MS, and MALDI-TOF MS. The native form of p42 was investigated using native-PAGE and Ferguson plot. Biotin-coupled property was examined by Western blot analysis. Enzymatic actions of p42 were studied using glutamate as substrate in the presence or absence of glutamine.Results: p42 was successfully purified from chick retinal protein solution using the molecular filtration. Western blot analysis with avidin showed that p42 was a biotin-coupled protein. Using SDS-PAGE, 2D-PAGE, LC-MS/MS, and MALDI-TOF MS, purified p42 was identified as a glutamine synthetase with four isoforms. Native-PAGE, followed by Ferguson plot analysis, showed two molecular forms of p42 corresponding to homotetramers and homooctamers. Enzymatic reaction followed by paper chromatography showed that p42 catalyzed the synthesis of glutamine from glutamate in the presence of ammonium ion, ATP, and magnesium ion. At prolonged reaction time, γ-aminobutyric acid (GABA) was also formed. With glutamate and glutamine present at equal concentrations in the reaction mixture, GABA could be rapidly detected, but GABA could not be detected when glutamate concentration was more than four-fold that of glutamine. The results indicated that p42 also had glutamate decarboxylase activity. Both enzymatic activities were inhibited by avidin. High concentrations of Mn2+ inhibited synthetase activity of p42 but not decarboxylase activity.Conclusion: p42 was purified from chick retinal protein solution using molecular filtration in the presence of sodium chloride. The protein was a biotin-coupled bifunctional enzyme that contained glutamine synthetase activity and glutamate decarboxylase activity. Biotin was possibly involved in these activities. Mn2+ showed different effects on the two activities.

Effects of ammonium ion, acetate and aerobic conditions on hydrogen production and expression levels of nitrogenase genes in Rhodobacter sphaeroides O.U.001

In the present study, expression levels of nitrogenase encoding nifH and control genes nifA and prrA were examined at different physiological conditions in Rhodobacter sphaeroides O.U.001. In addition to variations in expression levels, changes in hydrogen production and growth were also investigated in response to different concentrations of ammonium source, acetate and aerobic conditions. In the present study, increasing concentration of ammonium chloride was found to be caused decrease in hydrogen production. Glutamate containing medium had the capacity for higher hydrogen production. Hydrogen production was observed even in aerobic conditions. The expression levels of nifH and nifA genes decreased with the increasing concentrations of ammonium chloride. Although the expression of nifA was present in the highest concentrations of NH 4Cl under anaerobic conditions, no expression was observed under aerobic conditions of the same culture conditions. This was likely due to transcriptional level inhibition of nitrogenase in the presence of ammonium ion. Negative correlation was observed between the expression levels of prrA gene and its target, nifA gene.

Study on the Indirect Electrochemical Detection of Ammonium Ion with In Situ Electrogenerated Hypobromous Acid

AbstractThe electrochemical oxidation of bromide in the presence of ammonium ion (NH$\rm{ {_{4}^{+}}}$) was studied by cyclic voltammetry and UV‐vis spectroscopy. The experimental results suggested that the anodically generated bromine (Br2) would be hydrolyzed to hypobromous acid (HBrO) at the pH range of 5–7 and was further disproportionate to hypobromite anion (BrO−) when pH was larger than 7. Both HBrO and BrO− were confirmed to be participated in the following homogeneous chemical reaction with the coexisted ammonium ion. However, HBrO is electroactive whereas BrO‐ is electroinactive at carbon electrode. Based upon the reaction of HBrO with NH$\rm{ {_{4}^{+}}}$, an indirect electrochemical method was proposed for determination of NH$\rm{ {_{4}^{+}}}$ with dual‐electrode configuration in phosphate buffer solution (pH 7), where HBrO was produced at a generator electrode and the excess HBrO was subsequently detected at a collector electrode after a reaction with NH$\rm{ {_{4}^{+}}}$ in a batch solution or in a micro flow injection analytical (micro‐FIA) system by using an interdigitated array (IDA) Pt microelectrode and a carbon film ring‐disk electrode (CFRDE), respectively. The decreasing of reduction current at the collector electrode was proportional to the concentration NH$\rm{ {_{4}^{+}}}$ in both systems, with the detection limit below 3.0 μM. This approach shows the advantage of highly selectivity even in presence of a large amount of coexisted cations, and was successfully applied for the determination of NH$\rm{ {_{4}^{+}}}$ in environmental water samples.

Reaction of 2′-deoxycytidine with peroxynitrite in the presence of ammonium bromide

Peroxynitrite, a reactive nitrogen species generated from nitric oxide and superoxide anion radical, is an endogenous potential risk factor for human cancer. When 2′-deoxycytidine was incubated with peroxynitrite at neutral pH and 37 °C, the reaction was greatly enhanced by the addition of ammonium bromide. Both ammonium ion and bromide ion were required to exert the enhancing effect. In addition to ammonium ion, methylamine and dimethylamine exerted the enhancing effect in the presence of bromide ion. Two major products were identified as 5-hydroxy-2′-deoxycytidine and 5-bromo-2′-deoxycytidine. Hypochlorite solution and bromine water reacted with 2′-deoxycytidine generating 5-hydroxy-2′-deoxycytidine and 5-bromo-2′-deoxycytidine in the presence of ammonium bromide with the yields similar to those of the reaction of peroxynitrite with ammonium bromide. Fenton reaction of 2′-deoxycytidine was suppressed by the addition of ammonium bromide. Nitrogen dioxide gas did not react with 2′-deoxycytidine in the presence or the absence of ammonium bromide. These results suggest that in the presence of ammonium ion or amines, bromide ion interacts with peroxynitrous acid, which is a protonated form of peroxynitrite, but not with hydroxyl radical or nitrogen dioxide generated by homolysis of peroxynitrous acid, to form hypobromous acid. In the presence of ammonium ion or amines, bromide ion may play a role in enhancing the genotoxic effects of peroxynitrite in humans.

Molecular hydrogen production by nitrogenase of Rhodobacter sphaeroides and by Fe-only hydrogenase of Rhodospirillum rubrum

The genes coding for two PII-like proteins, GlnB and GlnK, which play key roles in repressing the nitrogenase expression in the presence of ammonium ion, were interrupted from the chromosome of Rhodobacter sphaeroides. The glnB–glnK mutant exhibits the less ammonium ion-mediated repression for nitrogenase compared with its parental strain, which results in more H 2 accumulation by the mutant under the conditions. Rhodospirillum rubrum produces H 2 by both nitrogenase and hydrogenase. R. rubrum containing the recombinant pRK415 with an insert of hydC coding for its own Fe-only hydrogenase showed twofold higher accumulation of H 2 in the presence of pyruvate under photoheterotrophic conditions, which was not observed in the absence of pyruvate. The same was true with R. rubrum containing the recombinant pRK415 cloned with hydA coding for Fe-only hydrogenase of Clostridium acetobutylicum. Thus, Fe-only hydrogenase requires pyruvate as an electron donor for the production of H 2.

Ammonium ions inhibit nitrogen fixation but do not affect heterocyst frequency in the bloom-forming cyanobacterium Nodularia spumigena strain AV1

In the presence of ammonium ion, Nodularia spumigena strain AV1, a filamentous, heterocystous cyanobacterium isolated from the Baltic Sea, lost aerobic nitrogen-fixation activity while maintaining heterocyst frequency along the filaments. Real-time RT-PCR showed that the expression of nifH (encoding the dinitrogenase reductase component of the nitrogenase enzyme) was suppressed and the levels of NifH protein decreased dramatically in response to treatment with ammonium. On the other hand, ntcA (encoding the global nitrogen regulator in cyanobacteria) and hetR (the key regulatory gene in heterocyst differentiation) were expressed and their expression patterns were not affected by the treatment with ammonium. These data demonstrate that N. spumigena strain AV1 maintains heterocyst frequency along the filaments in the presence of ammonium and in the absence of detectable N2-fixation activity.

Comparison of the effects of acylation and amidation on the antimicrobial and antiviral properties of lactoferrin

To compare amidation and acylation of lactoferrin (LF) from bovine milk, as a means of enhancing its antimicrobial and antiviral properties. LF was chemically modified by amidation with a 1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide (EDC) in the presence of ammonium ions or by acylation with either succinic or acetic anhydride. In the test systems used, amidation substantially enhanced the activity of LF against Pseudomonas fluorescens in comparison with native LF. However, increasing the net negative charge of LF by acylation had no effect on the activity of LF against P. fluorescens, and abrogated the antimicrobial activity of LF against Bacillus subtilis and Saccharomyces cerevisiae. Increasing the net negative charges of LF by acylation eliminated its antimicrobial and antiviral effects against poliovirus and feline calicivirus (nonenveloped viruses). The addition of positive charges to LF via amidation enhanced antimicrobial properties in contrast to increasing the negative charges by acylation, which abolished both the antimicrobial and antiviral properties of LF. The effects of charge alteration of LF determined in this study provides a basis for further development of LF formulations with enhanced antimicrobial effectiveness for use in food process hygiene, veterinary and health-care applications.

The molecular characterisation and antimicrobial activity of amidated bovine lactoferrin

Chemical modification of bovine lactoferrin (LF) by amidation increased the net positive charge of the protein and markedly enhanced its activity against most Gram-positive and Gram-negative bacteria tested, but not against Saccharomyces cerevisiae or Penicillium candidum. Bovine lactoferrin was amidated with 1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide in the presence of ammonium ions. Mass spectrometric analysis of the modified protein confirmed that amidation converted aspartyl or glutamyl residues to asparaginyl or glutaminyl residues. The changes in net charge and electrophoretic mobility of amidated LF were confirmed by electrophoretic and chromatographic methods. Isoionic point titration was used to determine changes to net charges and ion exchange chromatography results confirmed that the increased positive charge played an important role in the antimicrobial action of the amidated protein. Thus, chemical amidation of LF introduced substantial structural changes in the LF molecule, reflected in amino acid composition and increased net positive charge, and enhanced biological activity.

Identification of molecular species of simple lipids by normal phase liquid chromatography–positive electrospray tandem mass spectrometry, and application of developed methods in comprehensive analysis of low erucic acid rapeseed oil lipids

Mono-, di- and triacylglycerol (MAG, DAG, TAG), sterol ester (SE), free sterol (S) and free fatty acid (FFA) standards were analyzed in the presence of ammonium ions and ammonia by flow injection MS 2 and MS 3, and by normal phase-liquid chromatography (NP-LC) MS 2 positive electrospray ionization (ESI) mass spectrometry (MS). The MS data recorded for ammonium adducts ([ M + NH 4] +) of TAGs, DAGs, and MAGs were consistent with stepwise fragmentation mechanisms. In the first step, ammonium ion in [ M + NH 4] + donates proton to acylglycerol and ammonia is released. In the second step, FFA is cleaved from protonated TAG, water from protonated 1,3-DAG and MAG, both FFA and water from protonated 1,2-DAG, hence leading to formation of [DAG] + ion from TAG and 1,3-DAG, [DAG] + and [MAG] + ions from 1,2-DAG, and [MAG] + ion from MAG. In the third step, [DAG] + ion of TAG is fragmented to yield [Acyl] +, [Acyl + 74] +, [DAG − 74] + ions, [DAG] ion of 1,3-DAG to [Acyl] + ions, and [MAG] + ion of MAG to protonated FAs, which are decomposed to water and [Acyl] + ions in the fourth step. A stepwise mechanism for fragmentation of FFA was also evident from MS 2 and MS 3 data. Molecular species of low erucic acid rapeseed oil simple lipids were identified from characteristic ions produced in the NP-LC–ESI-MS 2 of [ M + NH 4] + ions. The percentage composition of the molecular species of each lipid class was calculated from integrated extracted ion chromatograms of [( M + NH 4)] + ions of SE, TAG, MAG, and FFA, of the sum of [( M + NH 4)] + and [( M + NH 4) − NH 3 − H 2O] + ions of both regioisomers of DAGs, and of sterol fragment ions of S.

Citrate inhibition-resistant form of 6-phosphofructo-1-kinase from Aspergillus niger.

Two forms of Aspergillus niger 6-phosphofructo-1-kinase (PFK1) have been described recently, the 85-kDa native enzyme and 49-kDa shorter fragment that is formed from the former by posttranslational modification. So far, kinetic characteristics have never been determined on the enzyme purified to near homogeneity. For the first time, kinetic parameters were determined for individual enzymes with respect to citrate inhibition. The native 85-kDa enzyme was found to be moderately inhibited by citrate, with the Ki value determined to be 1.5 mM, in the system with 5 mM Mg2+ ions, while increasing magnesium concentrations relieved the negative effect of citrate. An identical inhibition coefficient was determined also in the presence of ammonium ions, although ammonium acted as a strong activator of enzyme activity. On the other hand, the shorter fragment of PFK1 proved to be completely resistant to inhibition by citrate. Allosteric citrate binding sites were most probably lost after the truncation of the C-terminal part of the native protein, in which region some binding sites for inhibitor are known to be located. At near physiological conditions, characterized by low fructose-6-phosphate concentrations, a much higher efficiency of the shorter fragment was observed during an in vitro experiment. Since the enzyme became more susceptible to the positive control by specific ligands, while the negative control was lost after posttranslational modification, the shorter PFK1 fragment seems to be the enzyme most responsible for generating undisturbed metabolic flow through glycolysis in A. niger cells.

Thermally reactive phenylethynyl-terminated bis(benzylester) and bis(amide) monomers based on semi-enzymatically produced 6-phenylethynyl picolinic acid

The synthesis and isolation of 6-phenylethynyl picolinic acid (PEPCA; IUPAC name: 6-(2-phenylethynyl)pyridine-2-carboxylic acid) was first demonstrated when Acinetobacter sp. strain F4 was used to biotransform diphenylacetylene to the ring-fission product that underwent facile ring closure to form PEPCA in the presence of ammonium ions. Here, the structure and properties of PEPCA were confirmed by comparison with those of PEPCA that was chemically synthesized. In the chemical route, commercially available 6-bromopicolinic acid was first converted to methyl 6-bromopicolinate using methyl iodide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The resulting methylester was coupled with phenylacetylene by the palladium-catalyzed reaction to yield methyl 6-phenylethynyl picolinate, which was then hydrolyzed by sodium carbonate to afford PEPCA. Both enzymatically and chemically synthesized PEPCA were used to prepare its thermally reactive bis(benzylester) and bis(amide) derivatives. Thus, three phenylethynyl-terminated bis(amide) derivatives were synthesized by treating PEPCA with 1,3-phenylenediamine, 4,4′-oxydianiline or 4,4′-(hexafluoroisopropylidene)dianiline via dicyclohexylcarbodiimide (DCC)-mediated amidation. The bis(benzylester) derivative was prepared from PEPCA and α,α′-dibromo- p-xylene. All the intermediates and final products were characterized by FT-IR, NMR, MS and elemental analysis. The thermal properties of PEPCA and the reactive derivatives were characterized by DSC and TGA. The exothermic peaks of three bis(amide) derivatives were at least 20–40 °C lower than typically reported for the phenylethynyl compounds. Lowered reaction temperatures observed for the thermally-induced free radical polymerization of phenylethynyl groups were attributed to the strong electron-withdrawing capability of the pyridine moiety. Bis(amide) derivatives exhibited excellent thermal stability after previously cured at 300 °C for 30 min and 350 °C for 30 min.