2906-28-7Relevant academic research and scientific papers
Completing the folate biosynthesis pathway in Plasmodium falciparum: P-aminobenzoate is produced by a highly divergent promiscuous aminodeoxychorismate lyase
Magnani, Giovanni,Lomazzi, Michela,Peracchi, Alessio
, p. 149 - 155 (2013)
Enzymes that produce or recycle folates are the targets of widely used antimalarial drugs. Despite the interest in the folate metabolism of Plasmodium falciparum, the molecular identification of ADCL (aminodeoxychorismate lyase), which synthesizes the p-aminobenzoate moiety of folate, remained unresolved. In the present study, we demonstrate that the plasmodial gene PF14-0557 encodes a functional ADCL and report a characterization of the recombinant enzyme.
Influence of PVP-PEG mixed aggregates and electrolytes on the rate of alkaline hydrolysis of benzocaine in aqueous and surfactant medium
Aazam, Elham,Al-Lohedan, H. A.,Aldhayan, Daifallah M.,Ali, Mohd Sajid,Rafiquee, M. Z. A.,Rahman, Farheen
, (2020)
The present work describes the effects of the interactions between the two water-soluble polymers poly(vinyl pyrrolidone) (PVP) and poly(ethylene glycol) (PEG) on the rate of the alkaline hydrolysis of benzocaine. The roles of the surfactants cetyltrimethylammonium bromide (CTABr) and sodium dodecyl sulfate (SDS) in the binding of benzocaine with PVP-PEG mixed systems has also been explored through changes in the reaction rate. Our results revealed that the reaction rate decreases with the increasing [PVP] when [PEG] is fixed. Similarly, the rate of hydrolysis also decreases on increasing [PEG] while [PVP] is fixed. The combined rate constant values for the hydrolysis of benzocaine in the aqueous and mixed PVP-PEG system (kΨ) increases with increasing [CTABr] in the lower concentration range, then decreases with further increase in [CTABr], giving a peaked profile for kΨ vs. [CTABr]. The increase in [SDS] in the mixed PVP-PEG system decreases the rate of hydrolysis. Accordingly, the observed results show that the binding constant values (i.e., the degree of association) of benzocaine with PVP-PEG in the presence of CTABr and SDS are lower. Furthermore, increasing the molecular weight of PEG in the surfactant-PVP-PEG complex decreases the binding constant values of the benzocaine-polymer complex due to the formation of less compact aggregates. The effects of electrolytes (CH3COONa, NaCl, Na2SO4, and NaNO3) were also investigated, and they were found to decrease reaction rate.
A Titanium-Organic Framework as an Exemplar of Combining the Chemistry of Metal- and Covalent-Organic Frameworks
Nguyen, Ha L.,Gándara, Felipe,Furukawa, Hiroyasu,Doan, Tan L. H.,Cordova, Kyle E.,Yaghi, Omar M.
, p. 4330 - 4333 (2016)
A crystalline material with a two-dimensional structure, termed metal-organic framework-901 (MOF-901), was prepared using a strategy that combines the chemistry of MOFs and covalent-organic frameworks (COFs). This strategy involves in situ generation of an amine-functionalized titanium oxo cluster, Ti6O6(OCH3)6(AB)6 (AB = 4-aminobenzoate), which was linked with benzene-1,4-dialdehyde using imine condensation reactions, typical of COFs. The crystal structure of MOF-901 is composed of hexagonal porous layers that are likely stacked in staggered conformation (hxl topology). This MOF represents the first example of combining metal cluster chemistry with dynamic organic covalent bond formation to give a new crystalline, extended framework of titanium metal, which is rarely used in MOFs. The incorporation of Ti(IV) units made MOF-901 useful in the photocatalyzed polymerization of methyl methacrylate (MMA). The resulting polyMMA product was obtained with a high-number-average molar mass (26 850 g mol-1) and low polydispersity index (1.6), which in many respects are better than those achieved by the commercially available photocatalyst (P-25 TiO2). Additionally, the catalyst can be isolated, reused, and recycled with no loss in performance.
Catalytic Oxidative Deamination by Water with H2Liberation
Tang, Shan,Rauch, Michael,Montag, Michael,Diskin-Posner, Yael,Ben-David, Yehoshoa,Milstein, David
supporting information, p. 20875 - 20882 (2020/12/23)
Selective oxidative deamination has long been considered to be an important but challenging transformation, although it is a common critical process in the metabolism of bioactive amino compounds. Most of the synthetic methods developed so far rely on the use of stoichiometric amounts of strong and toxic oxidants. Here we present a green and efficient method for oxidative deamination, using water as the oxidant, catalyzed by a ruthenium pincer complex. This unprecedented reaction protocol liberates hydrogen gas and avoids the use of sacrificial oxidants. A wide variety of primary amines are selectively transformed to carboxylates or ketones in good to high yields. It is noteworthy that mechanistic experiments and DFT calculations indicate that in addition to serving as the oxidant, water also plays an important role in assisting the hydrogen liberation steps involved in amine dehydrogenation.
Nueleophile specificity in anthranilate synthase, aminodeoxychorismate synthase, isochorismate synthase, and salicylate synthase
Ziebart, Kristin T.,Toney, Michael D.
experimental part, p. 2851 - 2859 (2011/02/26)
Anthranilate synthase (AS), aminodeoxychorismate synthase (ADCS), isochorismate synthase (IS), and salicylate synthase (SS) are structurally homologous chorismate-utilizing enzymes that carry out the first committed step in the formation of tryptophan, fo
Spectroscopic and kinetic properties of the radical zwitterion and related intermediates in the one-electron oxidation of p-aminobenzoic acid
Tripathi,Su, Yali
, p. 2235 - 2244 (2007/10/03)
The time-resolved resonance Raman spectra and acid-base properties of the transient prepared on the submicrosecond time scale by N3. oxidation of aqueous p-aminobenzoic acid (PABA) in near-neutral solutions identify it as the charge-neutral 4--O2C-aniline.+ radical. This zwitterion intermediate undergoes slow thermal dissociation (K ~ 2.4 x 103 s-1) by intramolecular electron transfer and CO2 elimination. It reacts with common bases, such as OH-, N3-, and HPO22- ions, at the rate constants of 1.9 x 1010, 2.7 x 106, and 2.2 x 108 M-1 s-1, respectively, and converts into the nondissociative anilino radical form (pK(a) 6.7). In the .OH oxidation, formation of the zwitterion radical occurs via OH adducts (hydroxycyclohexadienyl radicals) of p-aminobenzoate anion, at a rate of 1.4 x 105 s-1 which is independent of the base concentration. In strongly acidic solutions the OH adduct of p-aminobenzoic acid reacts with H+, at a rate constant of 4.7 x 108 M-1 s-1, to form the 4-HO2C-aniline cation radical (pK(a) 1.1). The benzidine cation radical, observed as one of the transient secondary products in Raman experiments, results from the reactions of p-aminophenyl radical produced on dissociation of the 4--O2C-aniline.+ radical. The marked pH dependence of the nature and yields of the photoproducts of p-aminobenzoic acid, observed in several recent studies, is explained in terms of the dissociative properties of the zwitterion radical and its base-catalyzed conversion into the anilino radical. A two-state model has been developed for the explanation of the intramolecular electron transfer and bond dissociation in the radical intermediates with structurally stable ground electronic state.
