Amino Group Of Glycine Research Articles

Analysis of Anodic Linear Sweep Voltammograms Considering Insufficient Lability of Cu|Cu(II), Glycine System

Anodic LS voltammograms of the alkaline Cu|Cu(II), glycine system were converted into mass-transport corrected Tafel plots considering that the glycinate anion L− takes part in the first stage of copper ionization. The anodic current density was normalized relative to the surface concentration of L− species, which was determined using the mass transfer model of chemically interacting species. The lability of the system was assessed based on available kinetic characteristics and specific experimental data. To linearize the Tafel plots, corrections were made to account for the insufficient mobility of the proton attached to glycine amino group. Obtained Tafel constants indicate that the second step of copper ionization, involving the oxidation of the intermediate copper(I)-glycine complex, is the rate-determining step.

Photocatalytic degradation of methylene blue and rhodamine B using one-pot synthesized nickel oxide grafted glycine (NiO @GLY) nanostructured: Oxygen vacancies effect

A venerable challenge in environmental and materials science is the degradationof organic contaminants from wastewater using visible-light irradiation. The nickel oxide nanocomposite was synthesized using the facile one-pot combustion method at 550 °C. XRD, TEM, and N2 Sorption analysis confirmed the existence of mesoporous textured surfaces. Both spherical and hexagonal nanocrystals were produced with particle sizes ranging from 30 to 56 nm. The hexagonal nanocrystals appeared by increasing the glycine loading. The particle size of as-synthesized NiO @GLY was about 5–16 nm, with spherical morphology. The as-prepared hybrid composites were used to degrade harmful dyes. These produced systems seem to be governed by the interaction involving negatively charged nickel oxide nanoparticles and the amino group of glycine, as evidenced by zeta potential management. The degradation mechanism was found to follow the pseudo-first-order kinetics. S4 shows a promising result with degradation efficiency of 99 % methylene blue, 96 % rhodamine B, and 93 % for the mixed dye. The enhancement is related to oxygen vacancies, which support the photocatalyst's activity and stability.

Kinetic and structural evidence that Asp-678 plays multiple roles in catalysis by the quinoprotein glycine oxidase

PlGoxA from Pseudoalteromonas luteoviolacea is a glycine oxidase that utilizes a protein-derived cysteine tryptophylquinone (CTQ) cofactor. A notable feature of its catalytic mechanism is that it forms a stable product-reduced CTQ adduct that is not hydrolyzed in the absence of O2 Asp-678 resides near the quinone moiety of PlGoxA, and an Asp is structurally conserved in this position in all tryptophylquinone enzymes. In those other enzymes, mutation of that Asp results in no or negligible CTQ formation. In this study, mutation of Asp-678 in PlGoxA did not abolish CTQ formation. This allowed, for the first time, studying the role of this residue in catalysis. D678A and D678N substitutions yielded enzyme variants with CTQ, which did not react with glycine, although glycine was present in the crystal structures in the active site. D678E PlGoxA was active but exhibited a much slower kcat This mutation altered the kinetic mechanism of the reductive half-reaction such that one could observe a previously undetected reactive intermediate, an initial substrate-oxidized CTQ adduct, which converted to the product-reduced CTQ adduct. These results indicate that Asp-678 is involved in the initial deprotonation of the amino group of glycine, enabling nucleophilic attack of CTQ, as well as the deprotonation of the substrate-oxidized CTQ adduct, which is coupled to CTQ reduction. The structures also suggest that Asp-678 is acting as a proton relay that directs these protons to a water channel that connects the active sites on the subunits of this homotetrameric enzyme.

Acetyl Phosphate as a Primordial Energy Currency at the Origin of Life

Metabolism is primed through the formation of thioesters via acetyl CoA and the phosphorylation of substrates by ATP. Prebiotic equivalents such as methyl thioacetate and acetyl phosphate have been proposed to catalyse analogous reactions at the origin of life, but their propensity to hydrolyse challenges this view. Here we show that acetyl phosphate (AcP) can be synthesised in water within minutes from thioacetate (but not methyl thioacetate) under ambient conditions. AcP is stable over hours, depending on temperature, pH and cation content, giving it an ideal poise between stability and reactivity. We show that AcP can phosphorylate nucleotide precursors such as ribose to ribose-5-phosphate and adenosine to adenosine monophosphate, at modest (~2%) yield in water, and at a range of pH. AcP can also phosphorylate ADP to ATP in water over several hours at 50 °C. But AcP did not promote polymerization of either glycine or AMP. The amino group of glycine was preferentially acetylated by AcP, especially at alkaline pH, hindering the formation of polypeptides. AMP formed small stacks of up to 7 monomers, but these did not polymerise in the presence of AcP in aqueous solution. We conclude that AcP can phosphorylate biologically meaningful substrates in a manner analogous to ATP, promoting the origins of metabolism, but is unlikely to have driven polymerization of macromolecules such as polypeptides or RNA in free solution. This is consistent with the idea that a period of monomer (cofactor) catalysis preceded the emergence of polymeric enzymes or ribozymes at the origin of life.

Синтез та алкілування аміду, отриманого на основі N-фталоілгліцину та гідразиду ендикової кислоти

Himic acid hydrazide derivatives are promising in terms of practical use compounds due to their wide range of biological effects (primarily neurotropic activity) and their synthetic potential. Earlier investigated in detail the methods of synthesis of hydrazones, urea, amide and imide derivatives of himic acid hydrazide. Also known diverse biological action of N-Phthaloylglycine, which could serve as an effective protection for the amino group of glycine and has interesting structural features that contribute to the formation of supramolecular complexes. The methodology of synthesis of 2-(Phthalimidoyl)-N-benzyl-N-(4-azatricyclo[5.2.1.02-endo,6-endo]dec-8-ene-3,5-dione-4-yl)acetamide, including obtaining of 2-(Phthalimidoyl)-N-(4-azatricyclo[5.2.1.02-endo,6-endo]dec-8-ene-3,5-dione-4-yl)acetamide based on himic acid hydrazide acid and Phthalylglycyl chloride and alkylation of obtained product. Found that acceptable yield is observed during the alkylation reaction in boiling solution of anhydrous acetone in the presence of excess calcined potassium carbonate. The structure of obtained products was confirmed by analyzing the 1H NMR spectrum.

Removal of zinc(II) ion by graphene oxide (GO) and functionalized graphene oxide–glycine (GO–G) as adsorbents from aqueous solution: kinetics studies

The main purpose of this study is to explain the absorption of zinc from aqueous solution by grapheme oxide and functionalized grapheme oxide with glycine as the adsorbent surface. For confirmed functionalized graphene oxide, the glycine amino group was added to the surface of graphene oxide. The effects of the initial concentration of Zn(II) ions and contact time were studied. Results showed that with increasing initial concentration of Zn(II) ions, the adsorption capacity increased. The adsorption capacity did not show a large change after 50 min; therefore, for the study of kinetic parameters, the optimal time of 50 min was selected. The chemical structure of graphene oxide was confirmed by using FT-IR analysis. The adsorption process of Zn(II) ions graphene oxide and functionalized graphene oxide–glycine surfaces was fixed at 298 K and pH 6. The pseudo-first-order and the pseudo-second-order (types I, II, III and IV) kinetic models were tested for the adsorption process and the results showed that the kinetic parameters best fit type (I) of the pseudo-second-order model. A high R 2 was used to be the best match.

Synthetic and mechanistic insight into nosylation of glycine residues

The Fukuyama-Mitsunobu alkylation procedure is widely used to introduce alkyl substituents to amino groups in general and N-alkylation of peptides in particular. Here we have investigated the procedure in detail for N-alkylation of peptides with N-terminal glycine residues, based on the observation that standard conditions lead to substantial bis-nosylation of the glycine amino group. A systematic evaluation of this observation was carried out and it was demonstrated that for peptides with alanine, β-alanine or γ-aminobutyric acid (GABA) as N-terminal residues mono-nosylation was observed under the same conditions. Moreover, bis-nosylation was independent of the type of resin, neighboring amino acid and nature of the peptide. Calculations suggest that the reason for the bis-nosylation is the fact that the deprotonated mono-nosyl species is particularly stable in the case of the terminal Gly residue because the N(-) residue can become closer to the SO(2) unit. Finally, the mono-nosylated N-terminal glycine could be obtained by careful optimization of the procedure, adding only one equivalent of 2-nitrobenzenesulfonyl chloride.

The effect of partial methylation of the glycine amino group on crystal structure inN,N-dimethylglycine and its hemihydrate

N,N-Dimethylglycine, C(4)H(9)NO(2), and its hemihydrate, C(4)H(9)NO(2)·0.5H(2)O, are discussed in order to follow the effect of the methylation of the glycine amino group (and thus its ability to form several hydrogen bonds) on crystal structure, in particular on the possibility of the formation of hydrogen-bonded `head-to-tail' chains, which are typical for the crystal structures of amino acids and essential for considering amino acid crystals as mimics of peptide chains. Both compounds crystallize in centrosymmetric space groups (Pbca and C2/c, respectively) and have two N,N-dimethylglycine zwitterions in the asymmetric unit. In the anhydrous compound, there are no head-to-tail chains but the zwitterions form R(4)(4)(20) ring motifs, which are not bonded to each other by any hydrogen bonds. In contrast, in the crystal structure of N,N-dimethylglycinium hemihydrate, the zwitterions are linked to each other by N-H···O hydrogen bonds into infinite C(2)(2)(10) head-to-tail chains, while the water molecules outside the chains provide additional hydrogen bonds to the carboxylate groups.

Characterization of non-enzymatic acylation of amino or thiol groups of bionucleophiles by the acyl-adenylate or acyl-CoA thioester of cholic acid

Acyl-adenylates and acyl-CoA thioesters of bile acids (BAs) are highly electrophilic acyl-linked metabolites which can undergo transacylation reactions with amino and thiol groups of nucleophilic groups on acceptor molecules such as amino acids, peptides, and proteins. Here, non-enzymatic acylation at pH 7.4 of glycine, taurine, glutathione (GSH), and N-acetylcysteine (NAC) by cholyl-adenylate (CA-AMP) was compared with that mediated by cholyl-CoA thioester (CA-CoA) using a 1:1 mixture of stable isotopically labeled CA-AMP and unlabeled CA-CoA. The transacylation products of these substrates were analyzed by liquid chromatography/electrospray ionization linear ion-trap mass spectrometry in negative-ion detection mode. CA-AMP was more reactive than CA-CoA with the amino group of glycine or taurine than with the thiol group of GSH or NAC. In contrast, CA-CoA was more reactive than CA-AMP with the thiol group of GSH or NAC and was far less reactive with the amino group of glycine or taurine. These differences in the reactivity of CA-AMP as compared with that of CA-CoA towards amino and thiol groups may be attributed to the electrophilicity of the carbonyl carbon of these acyl-linked cholic acid metabolites and the nucleophilicity of the amino and thiol group in the bionucleophiles that were studied.

Structure of [Pb(Gly-H)]+ and the Monosolvated Water and Methanol Solvated Species by Infrared Multiple-Photon Dissociation Spectroscopy, Energy-Resolved Collision-Induced Dissociation, and Electronic Structure Calculations

Infrared multiple-photon dissociation (IRMPD) spectroscopy, collision-induced dissociation mass spectrometry, and theoretical calculations are combined to provide new insights into the structure and dissociation of lead(II) complexed with the conjugate acid of the amino acid glycine ([Pb(Gly-H)](+)) in the presence and absence of solvent. Unexpectedly, these experiments show the main site of lead(II) coordination to be the deprotonated amino group of glycine, with additional coordination to the carbonyl group. In such a structure lead(II) can act as an effective conduit for proton/hydrogen shifts, making H(2)O loss competitive with that of CO in the [Pb(Gly-H)](+) complex and leading to solvent deprotonation and formation of [PbOR(Gly)](+) (R = H, CH(3)) ions when solvent is present in the complex. The structural assignments based on IRMPD spectroscopy are complemented with isotopic labeling experiments (H(2)(18)O) and experiments done on the ethyl ester of glycine.

Synthesis and characterization of heterotelechelic poly(ethylene glycol)s with amino acid at one end and hydroxyl group at another end

AbstractHeterotelechelic poly(ethylene glycol)s are widely used in the modification, conjugation, and crosslinking of biomacromolecules. A series of heterotelechelic PEGs with amino acid at one end and hydroxyl group at another end, including α‐glycine‐ω‐hydroxyl‐PEG, α‐proline‐ω‐hydroxyl‐PEG, and α‐phenylalanine‐ω‐hydroxyl‐PEG, were first synthesized in this study. The reaction proceeded at ambient temperature under alkaline conditions via an aqueous solution polymerization of ethylene oxide. Amino group of glycine, proline, and phenylalanine was the initiating center in the polymerizations, and carboxyl group of these amino acids was reserved as one of the active end groups of the obtained heterotelechelic PEG. Purification of the desired products was accomplished by silica gel column chromatography. The obtained heterotelechelic PEGs were characterized by means of FT‐IR, 1H NMR, 13C NMR, MS, and RP‐HPLC. They were in different forms depending on the type of initiating amino acid, e.g. α‐glycine‐ω‐hydroxyl‐PEG and α‐phenylalanine‐ω‐hydroxyl‐PEG are in branched form, and α‐proline‐ω‐hydroxyl‐PEG is linear. Amino acids were conjugated to PEG chains through the stable carbon–nitrogen bond. Compared with the traditional critical polymerization conditions, the advantage of this method is that various amino acid ended heterotelechelic PEGs can be designed and obtained by using different amino acid as the initiator through a much more convenient route, which proceeded in aqueous solution at ambient temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Novel synthesis of α-PNA monomers by U-4CR

A novel synthesis of alpha-PNA monomers was carried out by U-4CR, followed by photochemical cleavage of the 2-nitrobenzyl group and selective hydrolysis in the presence of 10% HCl in THF. Three of four functional components in the U-4CR were specially protected: cyclohexenyl isocyanide, Boc for protecting the amino group of glycine, and 2-nitrobenzyl group as a photocage (photoremovable protecting group) for ammonia. The amino group of aldehyde-containing adenine is too weak to interfere with the U-4CR, so that it is not necessary to be protected.

Characterization of DNA−Protein Cross-Links Induced by Oxanine: Cellular Damage Derived from Nitric Oxide and Nitrous Acid

Reactive nitrogen species are implicated in inflammatory diseases and cancers. Oxanine (Oxa) is a DNA lesion derived from the guanine base with nitric oxide, nitrous acid, or N-nitrosoindoles. It was shown by gel electrophoresis that oxanine mediated the formation of DNA-protein cross-links (DPCs) with DNA-binding proteins and in the cell extract. Although 2'-deoxyoxanosine was shown to react with amines including the N-terminal amino group of glycine, the structures of DNA-protein cross-links induced by oxanine have not been characterized. In this study, we find that the thiol group of the amino acid side chain is reactive toward oxanine, forming a thioester. Two reaction products of oxanine, namely, the thioester and the amide adducts, with the endogenous tripeptide glutathione (GSH) as a model protein were characterized on the basis of their UV, NMR (1H- and 13C-), and mass spectra. Interestingly, the disulfide GSSG also reacts with oxanine, forming the thioester adduct. The thioester and the amide adducts are generated when GSH and GSSG react with oxanine-containing calf thymus DNA, and they might be possible forms of cellular DPCs. Because the repair mechanism of DPCs is not extensively investigated, the characterization of oxanine-derived DPC structures should shed light on their detection in vivo and on their biological consequences.

Molecular Orbital Calculations on the Protonation of Hydrogen-Bonded Formamide Chains. Implications for Peptides

We report density functional studies of the protonation of H-bonded formamide chains containing up to 10 monomeric units. These chains contain H bonds that are similar to those in peptides and proteins. All structures considered were completely geometrically optimized at the B3LYP/D95** level of calculation. The proton affinities of the chains are greatest at the terminal CO oxygen atoms. They increase significantly with the length of the formamide chain from two to five formamides. Protonation of the terminal CO of chains containing five or more formamides results in the transfer of the NH proton of the terminal (protonated) monomer across the H bond to the adjacent formamide. Protonations at the NH2 termini of the formamide chains are generally unfavorable as they result in the rupture of the proximate H bond. The proton affinities at the CO's of formamide chains containing three or more monomers exceed that of the amino group of glycine, implying that peptides that contain such H-bonding chains might b...

Separation of structurally related peptides by open-tubular capillary electrochromatography using (metallo)porphyrins as the adsorbed stationary phase

Several (metallo)porphyrins, particularly the porphyrin derivative tetraphenylporphyrin, and complexes of porphyrin derivatives with metal ions (Zn 2+, Cu 2+, Ni 2+, Co 2+, Co 3+) have been employed as the stationary phase physically adsorbed onto the inner fused-silica capillary surface for open-tubular capillary electrochromatography, and applied for the separation of structurally related peptides. Four octapeptides, derivatives of the B23–B30 fragment of the B-chain of human insulin with minor changes in their sequences (presence of lysine or ornithine in position B-29, presence or absence of phenylacetyl protecting group on the amino group of lysine/ornithine or N-terminal amino group of glycine), were studied as model analytes. Separations were performed both in alkaline (pH 9.0) and in acidic (pH 2.25) background electrolytes, and the changes in the migration/retention behaviour of the model set of peptides were investigated with respect to the porphyrin periphery/central metal atom and the charge of the octapeptides modified. The key moment of successful separation of these peptides seems to be the accessibility of functional groups of the peptides to the interaction with the modifiers tested herein.

1,5-Anhydro-D-fructose, a New Material for Modification of Amino Groups as Demonstrated Using Amino Acid and Proteins.

1, 5-Anhydro-D-fructose (1, 5-anhydro-D-arabino-hexo-2-close, 1, 5-AF) reacted well with the amino group and seemed to be useful as a reagent for modification of the amino compounds. The rate of browning of 1, 5-AF by reaction with glycine was higher than those of glucose and xylose at 50°C and pH 7.5. Forty-five percent of the amino group of glycine was modified by the incubation of a lyophilized mixture of 1, 5-AF and glycine at 30°C for 48 h, whereas the degree of modification by glucose was less than 5%. This modification was applied to lysozyme. A mass spectrum indicated that the sugar moiety was incorporated into the lysozyme. The optimum pH values of the modified and unmodified lysozyme on glycolchitin were pH 4.5 and 5.0, respectively. On the other hand, the optimum pH of the modified enzyme on freeze-dried cells of Micrococcus lysodeikticus shifted from pH 7.8 to 6.0. Wheat proteins, gliadin and glutenin, were also modified. The modified gliadin had higher emulsification ability and solubility than the unmodified ones.

Synthesis of N-Boc and N-Fmoc dipeptoids with nucleobase residues as peptoid nucleic acid monomers

The synthesis of Boc and Fmoc protected peptoid nucleic acid monomers bearing thymine (4a, 4b), adenine (6a, 6b) or guanine (7a, 7b) on the side chain is described. These nucleobases were attached to the amino group of glycine via an ethylene linkage using the Mitsunobu reaction, except cytosine, which was attached using alkylation. After deprotection, these amino acids have been used for synthesizing N-Boc and N-Fmoc dipeptoids.

抱合反応の機構解析と構造決定

Glycine conjugation is the most important route of detoxification, not only of many xenobiotic carboxylic acids but also of endogenous acids. However, the first reaction of glycine conjugation in some cases is reported to involve a class of active intermediates implicated in toxicity. The pathway of glycine conjugation consists of two sequential reactions. To elucidate the factors that regulate glycine conjugation, benzoic acid derivatives, acyl-CoAs as the active intermediates and glycine conjugates were simultaneously determined by LC-ESI-MS. Three compounds were collected from the microdialysis probe immersed into mitochondrial incubation mixture. A rate-limiting step was found to be the linkage to the amino group of glycine in a reaction that is catalyzed by acyl-CoA glycine: N-acyltransferases. However, the medium chain acyl-CoA synthetase catalyzing the initial reaction of glycine conjugation was the rate-limiting enzyme. Further, it was suggested that the stability of acyl-CoAs is one of the factors that determine the metabolic fate of xenobiotics containing a carboxylic group.

Reactivity of 2'-deoxyoxanosine, a novel DNA lesion.

2'-Deoxyoxanosine (dOxo) is a novel DNA lesion produced from 2'-deoxyguanosine by the reaction with nitrous acid or nitric oxide. We found that dOxo reacted with glycine under physiological conditions. The product was identified by spectrometric data as an adduct between the six membered ring of dOxo and an amino group of glycine. The adduct was more stable than dOxo under physiological conditions. The incubation of an oligodeoxynucleotide containing dOxo with glycine gave also rise to the adduct. These results suggest that dOxo formed in DNA reacts with amino groups of various compounds around DNA in vivo resulting in the adduct.

Biological activities of oligoketide pigments of Monascus purpureus

Rubropunctatin (1), monascorubrin (2), monascin (3) and ankaflavin (4) were purified from the mycelium of Monascus purpureus by flash chromatography on silica gel or reversed phase. Their embryotoxicity towards chicken embryos decreased in the order 2> 1> 3> 4. The lower homologues 1 and 3 exhibited teratogenic effects on these organisms. Significant antibiotic activities against Bacillus subtilis and Candida pseudotropicalis were found with compounds 1 and 2. Immunosuppressive activity on mouse T-splenocytes was most pronounced with compounds 3 and 4. None of the compounds showed significant cytotoxic activity towards rat hepatocytes in vitro. Incubation of resting cells of M. purpureus with glycine afforded the dark-red compounds 5 and 6 where the pyran moiety of 1 and 2 changed into the N-substituted dihydropyridine moiety by replacement of the O-atom by the amino group of glycine. Compounds 5 and 6 were less biologically active than the major pigments 1 - 4.