- Under-flame oxidation of amines and amino acids in an aqueous solution
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Flames from town gas-oxygen, hydrogen-oxygen, and ethylene-oxygen mixtures, when blown against the surface of an aqueous solution of amines and amino acids, induced an oxidation reaction in the aqueous phase, while an acetylene-oxygen flame failed to oxidize the compounds in solution. The hydrogen flame caused direct hydroxylation of the aromatic rings of phenylglycine homologs. The isomeric ratio of o-, m-, and p-hydroxyphenyl- amino acids produced was in accordance with that obtained by using the reaction systems of Fe2+-H2O2-EDTA and Fe2+-ascorbic acid-H2O2-EDTA, which are known to involve a hydroxyl radical as the agent for hydroxylating the aromatic rings. These results strongly suggest that the active species of flame-induced oxidation in an aqueous solution was the hydroxyl radical which was produced in the flames and extracted into the aqueous phase.
- Nomoto, Shinya,Shimoyama, Akira,Shiraishi, Susumu,Sahara, Denzo
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- Post-Translational Formation of Aminomalonate by a Promiscuous Peptide-Modifying Radical SAM Enzyme
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Aminomalonate (Ama) is a widespread structural motif in Nature, whereas its biosynthetic route is only partially understood. In this study, we show that a radical S-adenosylmethionine (rSAM) enzyme involved in cyclophane biosynthesis exhibits remarkable catalytic promiscuity. This enzyme, named three-residue cyclophane forming enzyme (3-CyFE), mainly produces cyclophane in vivo, whereas it produces formylglycine (FGly) as a major product and barely produce cyclophane in vitro. Importantly, the enzyme can further oxidize FGly to produce Ama. Bioinformatic study revealed that 3-CyFEs have evolved from a common ancestor with anaerobic sulfatase maturases (anSMEs), and possess a similar set of catalytic residues with anSMEs. Remarkably, the enzyme does not need leader peptide for activity and is fully active on a truncated peptide containing only 5 amino acids of the core sequence. Our work discloses the first ribosomal path towards Ama formation, providing a possible hint for the rich occurrence of Ama in Nature.
- Chen, Heng,Deng, Zixin,Ding, Wei,Ji, Xinjian,Li, He,Ma, Suze,Zhang, Qi
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- OXIDATIVE DEGRADATION OF HYDROXY AMINO ACIDS BY CONTACT GLOW DISCHARGE ELECTROLYSIS
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Oxidative degradation of several hydroxy amino acids was carried out in order to confirm the reaction pathway of the oxidative degradation of β- and γ-amino acids by contact glow discharge electrolysis.The results indicate that the reaction products from hydroxy amino acids support the hypothesis that the oxidative degradation of β- and γ-amino acids pass through hydroxy amino acids.
- Harada, Kaoru,Terasawa, Jun-ichi,Gunji, Hiromi
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- Thermodynamics of Protonation and Copper(II) Complex Formation of α-Aminomalonic acid
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The thermodynamic function (ΔG0, ΔH0 and ΔS0) for the protonation of α-aminomalonic acid were determined in aqueous solution (25 deg C, I=0.1 mol dm-3 NaCl).The basicity constants and enthalpy changes were evaluated from potentiometric and calorimetric data for both the primary amino and the carboxylate groups.On the basis of the thermodynamic changes a closed structure is hypothesized with the protonated amino nitrogen hydrogen-bonded to both the carboxylate groups to form two five-membered rings.The protonation of the CO2- groups provokes opening of the ring s.A relatively high stability constant for complexation with Cu2+ was determined, however in a narrow range of low pH.The co-ordination to the copper(II) occurs both with nitrogen and the two oxygen donor atoms, to form two five-membered chelate rings.
- Barbucci, Rolando,Casolaro, Mario,Fini, Adamo
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- Convenient method for reduction of C-N double bonds in oximes, imines, and hydrazones using sodium Borohydride-Raney ni system
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(Chemical Equation Presented) A practical method has been developed for reduction of C-N double bond in oximes, imines, and hydrazones with sodium borohydride catalyzed by Raney Ni. The reactions were carried out in basic aqueous solution, and the desired products were obtained in moderate yields after a simple procedure. This method can be applied to synthesize simpler aliphatic or aromatic amines and its analogs. Copyright Taylor & Francis Group, LLC.
- Yang, Yihua,Liu, Shouxin,Li, Junzhang,Tian, Xia,Zhen, Xiaoli,Han, Jianrong
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experimental part
p. 2540 - 2554
(2012/07/27)
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- RENIN INHIBITORS IV
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The invention concerns novel renin-inhibitory peptides which are useful for treating renin-assocated hypertension, hyperaldosteronism, and congestive heart failure. Processes for preparing the peptides, compositions containing them and methods of using them are included. Also included is a diagnostic method which uses the compounds to determine the presence of renin-associated hypertension or hyperaldosteronism.
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- OXIDATION REACTION OF AMINO ACIDS IN AQUEOUS SOLUTION INDUCED BY ARGON ARC PLASMA
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It was found that Argon arc plasma induced a powerful and clean stepwise oxidation reaction in aqueous solution containing various amino acids without using any oxidizing agent.
- Harada, Kaoru,Takasaki, Michiaki
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p. 4839 - 4842
(2007/10/02)
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