- Synthesis and catalytic activity of histidine-based NHC ruthenium complexes
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Main-chain C,N-protected histidine has been successfully alkylated at both side-chain nitrogens. The corresponding histidinium salt was metallated with ruthenium(ii) by a transmetalation procedure, thus providing histidine-derived NHC ruthenium complexes. These bio-inspired complexes show appreciable activity in the catalytic transfer hydrogenation of ketones. The Royal Society of Chemistry 2011.
- Monney, Angele,Venkatachalam, Galmari,Albrecht, Martin
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- Chemically Fueled Dissipative Self-Assembly that Exploits Cooperative Catalysis
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In living systems, dissipative processes are driven by the endergonic hydrolysis of chemical fuels such as nucleoside triphosphates. Now, through a simple model system, a transient self-assembled state is realized by utilizing the catalytic effect of histidine on the formation and breaking of ester bonds. First, histidine facilitates the ester bond formation, which then rapidly co-assembles to form a self-supporting gel. An out-of-equilibrium state is realized owing to the cooperative catalysis by the proximal histidines in the assembled state, driving the second pathway and resulting in disassembly to sol. Cooperative effects that use the dual role of imidazoles as nucleophile and as proton donor is utilized to achieve transient assemblies. This simple system mimics the structural journey seen in microtubule formation where the substrate GTP facilitates the non-covalent assembly and triggers a cooperative catalytic process, leading to substrate hydrolysis and subsequent disassembly.
- Bal, Subhajit,Das, Krishnendu,Ahmed, Sahnawaz,Das, Dibyendu
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- The study of the effect of histidine derivatives as a novel antinociceptive and anti-inflammatory activity
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This study explains the biochemical activity of histidine derivatives The compounds were identified by CHN analysis, FT-IR and H1 NMR. The results certified that the chemical structures of the prepared compounds. The anti-inflammatory and antinociceptive activity was studied by two different tests; the hot plate test and writhing test for analgesic activity and two tests for anti-inflammatory activity they are formalin induced inflammation test and carrageen an induced inflammation test. The histidine derivatives were found to have potent activity as anti-inflammatory and antinociceptive. The active compounds were tested to acute toxicity. It was found that they are safety to the dose 5 g/kg orally in mice without any mortality. Copyright E-Journal of Chemistry 2004-2011.
- Ramadhan, Usama H.,Al-Salihi, Niran J.
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- Synthesis, spectroscopic and X-ray characterization of various pyrazine-bridged platinum(II) complexes:1H NMR comparative study of their catalytic abilities in the hydrolysis of methionine- and histidine-containing dipeptides
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Four pyrazine (pz)-bridged Pt(II) complexes, [{Pt(1,3-pd)Cl}2(μ-pz)]Cl2·LiCl (1) (1,3-pd = 1,3-propylenediamine), [{Pt(2,2-diMe-1,3-pd)Cl}2(μ-pz)]Cl2·2[Li(H2O)4]Cl·2H2O (2) (2,2-diMe-1,3-pd = 2,2-dimethyl-1,3-propylenediamine), [{Pt(1,3-pnd)Cl}2(μ-pz)](ClO4)2·H2O (3) (1,3-pnd = (±)-1,3-pentanediamine) and [{Pt(1,3-pnd)Cl}2(μ-pz)]Cl2·2[Pt(1,3-pnd)Cl2]·2H2O (4) have been synthesized. NMR and UV-Vis spectroscopic characterization has been performed for compounds 1-3, while single-crystal X-ray analysis has been carried out for complexes 2 and 4. Atomic distribution in the crystals of 4 indicated a disorder which could be attributed to the presence at the same crystallographic site of four distinct stereoisomers of the [{Pt(1,3-pnd)Cl}2(μ-pz)]2+complex cation. The presence of four stereoisomeric products was also observed in complex 3 by13C NMR spectroscopy. Complexes 1-3 were converted into the corresponding aqua complexes, [{Pt(X)(H2O)}2(μ-pz)]4+(X is 1,3-pd, 2,2-diMe-1,3-pd and 1,3-pnd, respectively), and1H NMR spectroscopy was applied for comparison of their catalytic activities with those of the analogous mononuclear [Pt(X)(H2O)2]2+and pyrazine-bridged [{Pt(en)(H2O)}2(μ-pz)]4+complexes in the hydrolysis of the N-acetylated l-methionylglycine (Ac-l-Met-Gly) and l-histidylglycine (Ac-l-His-Gly). All reactions were performed in the pH range 2.0-2.5 at 37 °C. It was found that all investigated dinuclear Pt(II)-aqua complexes promote selective cleavage of the amide bond involving carboxylic group of the anchoring amino acid methionine in the Ac-l-Met-Gly or histidine in the Ac-l-His-Gly.1H NMR data indicate that neither the size of the chelated diamine ring (five-membered in ethylenediamine and six-membered in 1,3-propylenediamine) nor the bulky substituents incorporated into the 1,3-propylenediamine ligand have significant influence on the rate of hydrolysis of Ac-l-Met-Gly dipeptide. Meanwhile, the rate of hydrolysis of Ac-l-His-Gly depends on both of these factors and decreases in order en > 1,3-pd > 1,3-pnd > 2,2-diMe-1,3-pd. Moreover, it has been shown that all investigated dinuclear Pt(II)-aqua complexes are better catalytic agents in the hydrolysis of the dipeptides than the analogous mononuclear Pt(II)-aqua complexes. The present findings are expected to play a crucial role in the development of new Pt(II) complexes, which can act as effective catalytic reagents for the selective hydrolysis of peptides containing either methionine or histidine residues.
- Rajkovi?, Sne?ana,?ivkovi?, Marija D.,Warzajtis, Beata,Rychlewska, Urszula,Djuran, Milo? I.
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- Emergence of a Promiscuous Peroxidase Under Non-Equilibrium Conditions**
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Herein, we report the substrate induced generation of a transient catalytic microenvironment from a single amino acid functionalized fatty acid in presence of a cofactor hemin. The catalytic state accessed under non-equilibrium conditions showed acceleration of peroxidase activity resulting in degradation of the substrate and subsequently led to disassembly. Equilibrated systems could not access the three-dimensional microphases and showed substantially lower catalytic activity. Further, the assembled state showed latent catalytic function (promiscuity) to hydrolyze a precursor to yield the same substrate. Consequently, the assembly demonstrated protometabolism by exploiting the peroxidase-hydrolase cascade to augment the lifetime and the mechanical properties of the catalytic state.
- Bal, Subhajit,Das, Dibyendu,Pal, Sumit,Reja, Antara,Tikader, Baishakhi
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supporting information
(2021/12/06)
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- Effects of Imidazole and Its Derivatives on Radiation-Induced Dephosphorylation of Glycero-1-Phosphate in Deaerated Aqueous Solutions
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Abstract: The effect of imidazole, histamine, histidine, and their nitro derivatives on the radiation-induced transformations of glycero-1-phosphate and ethanol in deaerated aqueous solutions at pH 7 has been studied It has been found that the test substances in equimolar concentrations to glycero-1-phosphate inhibit the radiation-induced dephosphorylation by scavenging the radical products of water radiolysis. At an additive-to-substrate ratio of 1 : 100, the nitro derivatives of histidine and metronidazole efficiently inhibit the radiation-induced dephosphorylation of glycero-1-phosphate due to the interaction with its carbon-centered radicals with constants of (3.1–5.1) × 109 L mol–1 s–1. Using the radiolysis of a 1 M aqueous solution of ethanol, it was demonstrated that 5-nitroimidazoles quantitatively oxidize α-hydroxyethyl radicals; this manifested itself in the absence of 2,3-butanediol among the radiolysis products and a ~20-fold increase in the yield of acetaldehyde, as compared to that in a control experiment. Thus, metronidazole and the nitro derivatives of histidine are capable of suppressing the radiation-induced dephosphorylation of glycero-1-phosphate and, probably, glycerophospholipids due to the oxidation of their α-hydroxylcontaining carbon-centered radicals.
- Brinkevich,Maliborskii, A. Ya.,Melnichuk,Sverdlov,Grigor’ev, Yu. V.,Shadyro
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p. 155 - 164
(2021/04/22)
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- Synthesis of Imidazole and Histidine-Derived Cross-Linkers as Analogues of GOLD and Desmosine
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Amino acid derivatives with a central cationic heterocyclic core (e.g., imidazolium) are biologically relevant cross-linkers of proteins and advanced glycation end (AGE) products. Here, imidazolium-containing cross-linkers were synthesized from imidazole or histidine by N-alkylation employing aspartate- and glutamate-derived mesylates as key step. Biological investigations were carried out to probe the biocompatibility of these compounds.
- Sch?del, Nicole,Icik, Esra,Martini, Maike,Altevogt, Luca,Ramming, Isabell,Greulich, Andreas,Baro, Angelika,Bilitewski, Ursula,Laschat, Sabine
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supporting information
p. 2260 - 2268
(2021/03/04)
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- Peptide Tyrosinase Activators
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Peptides that increase melanin synthesis are provided. These peptides include pentapeptides YSSWY, YRSRK, and their variants. The peptides may activate the enzymatic activity of tyrosinase to increase melanin synthesis. The pharmaceutical, cosmetic, and other compositions including the peptides are also provided. The methods of increasing melanin production in epidermis of a subject are provided where the methods include administering compositions comprising an amount of one or more peptides effective to increase the melanin production. The methods also include treating vitiligo or other hypopigmentation disorders with compositions including one or more peptides.
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- A fundamental study of amadori rearrangement products in reducing sugar-amino acid model system by electrospray ionization mass spectrometry and computation
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It is crucial to characterize Amadori rearrangement products (ARPs) formed in the early stage of Maillard reaction, one of the most important modifications in food science. We setup a reaction model system using six selected amino acids (arginine, asparagines, glutamine, histamine, lysine and tryptophan) and their N-terminal acetylated forms with different reducing sugars for a fundamental study of Amadori rearrangement products. The effects on forming Amadori rearrangement products were studied by using electrospray ionization mass spectrometry (ESI-MS). The reaction rate was affected by reaction temperature, reaction time, property of sugars and amino acids and the fragmentation mechanism of Amadori rearrangement products was illustrated by tandem MS (MS2) with collision-induced dissociation. The proposed fragmentation mechanism of Amadori rearrangement products in MS2 was provided based on MS2 data and it was supported by their computational data of density functional theory (DFT) at the B3LYP/6-31++G(d,p) level.
- Zhang,Ruan,Wang,Ruan,Shao,Aalhus,Juárez
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p. 2941 - 2944
(2014/06/09)
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- PH-SENSITIVE IMAGING AGENTS
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Composition and method for surface-functionalized SPION-based agents. Such agents can provide highly pH-sensitive MRI contrast in tissue.
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Paragraph 0323; 0324
(2014/05/20)
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- Reactions of substituted aspirins with amino acids
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Acyl transfers are key reactions in biology and in the laboratory. In biological systems they are involved in energy transport, in the assembly of complex molecules and in the mechanisms of efficient action of many hydrolytic enzymes. We report a mechanistic and calculational study of the selective N-acylation reactions of amino acids by substituted aspirins, under mild conditions, in water at 25 °C. The acetylated amino-acid products of the reactions were identified by nuclear magnetic resonance, and the reaction steps were studied by density functional theory. Copyright
- Orth, Elisa S.,Medeiros, Michelle,Souza, Bruno S.,Caon, Natalia B.,Kirby, Anthony J.,Nome, Faruk
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supporting information
p. 939 - 945
(2014/01/06)
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- Kinetics and mechanism of thermal decomposition of kynurenines and biomolecular conjugates: Ramifications for the modification of mammalian eye lens proteins
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Thermal degradation reactions of kynurenine (KN), 3-hydroxykynurenine (3OHKN), and several adducts of KN, to amino acids and reduced glutathione (GSH) have been studied at physiological temperature. These compounds are all implicated in age-related mammalian eye lens cataract formation at the molecular level. The main reaction pathway for both KN and 3OHKN is deamination viaβ-elimination to carboxyketoalkenes CKA and 3OHCKA. These reactions show a weak pH dependence below pH values of ～8, and a strong pH dependence above this value. The 3OHKN structure deaminates at a faster rate than KN. A mechanism for the deamination reaction is proposed, involving an aryl carbonyl enol/enolate ion, that is strongly supported by the structural, kinetic, and pH data. The degradation of Lys, His, Cys and GSH adducts of the CKA moieties was also studied. The Lys adduct was found to be relatively stable over 200 h at 37 °C, while significant degradation was observed for the other adducts. The results are discussed in terms of known post-translational modification reactions of the lens proteins and compared to incubation studies involving KN and related compounds in the presence of proteins.
- Kopylova, Lyudmila V.,Snytnikova, Olga A.,Chernyak, Elena I.,Morozov, Sergey V.,Forbes, Malcolm D. E.,Tsentalovich, Yuri P.
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experimental part
p. 2958 - 2966
(2011/02/25)
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- A magnetic biomimetic nanocatalyst for cleaving phosphoester and carboxylic ester bonds under mild conditions
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As a result of the unique surface structure of nanospheres, Asp and His residues supported on a 12 nm maghemite nanoparticle worked collaboratively as a biomimetic nanocatalyst for hydrolyzing paraoxon (phosphoester) and 4-nitrophenyl acetate (carboxylic ester) in Milli-Q water (pH 7.0) at 37 °C, without employing extremes of pH or heavy metals. Our nanocatalyst could be facilely recovered via magnetic concentration. The isolated catalyst exhibited long-term stability, showing no significant loss of its catalytic activity for repeated uses after 3 months.
- Zheng, Yan,Duanmu, Chuansong,Gao, Yong
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p. 3215 - 3217
(2007/10/03)
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- New regioselectivity in the cleavage of histidine-containing peptides by palladium(II) complexes studied by kinetic experiments and molecular dynamics simulations
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Palladium(II) complexes promote hydrolytic cleavage of amide bonds in N- acetylhistidylglycine (AcHis-Gly), N-acetylhistidine (AcHis), and their derivatives methylated at the N-1 or N-3 atom of imidazole. Methylation controls coordination of imidazole to palladium(II) and allows stereochemical analysis of the reactions. The complex [PdCl4]2- regioselectively cleaves the amide bond involving the carboxylic group of histidine, the bond His- Gly; the rate constants of cleavage are virtually the same when the peptides coordinate to palladium(II) via the N-1 and the N-3 atom. The complex [Pd(H2O)4]2+ cleaves, at comparable rates, the amide bonds involving both the carboxylic (His-Gly) and the amino (AcHis) groups of histidine in the acetylated dipeptide. This unprecedented reactivity is examined by theoretical calculations in which molecular dynamics and solution of Poisson- Boltzmann equation are combined in a new way. When the Pd(H2O)32+ group is attached to the N-1 atom, both scissile bonds can be cleaved by internal delivery of aqua ligands. When the Pd(H2O)32+ group is attached to the N- 3 atom, both scissile bonds can be cleaved by internal delivery of aqua ligands and by external attack of water; in some conformers the two modes of cleavage may be combined in the reaction mechanism. In both N-1 and N-3 linkage isomers internal delivery seems to be assisted by weak hydrogen bonding. The rate constants for cleavage by [Pd(H2O)4]2+ are approximately 10 times greater than those for cleavage by [PdCl4]2-. This difference is explained semiquantitatively by consideration of the aquation equilibria involving [PdCl4]2-. This study shows that kinetics and regioselectivity of peptide cleavage may be controlled simply by choosing ligands in palladium(II) complexes. This is another step in our development of simple metal complexes as artificial metallopeptidases.
- Parac, Tatjana N.,Ullmann, G. Matthias,Kosti?, Nenad M.
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p. 3127 - 3135
(2007/10/03)
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- Cosmetic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamine derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- New selectivity and turnover in peptide hydrolysis by metal complexes. A palladium(II) aqua complex catalyzes cleavage of peptides next to the histidine residue
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This seems to be the first report that a transition-metal complex bonded to a histidine residue effects hydrolytic cleavage of a peptide next to this residue. Dipeptides AcHis-Aa in which the C-terminal amino acid designated Aa is Gly, Ala, Ser, Thr, Leu, Phe, and Tyr are completely hydrolyzed at 60 °C and 1.46 ≤ pD ≤ 2.61 in the presence of cis-[Pd(en)(H2O)2]-2+. The reaction is conveniently monitored by 1H NMR spectroscopy, and we report the kinetics. The reaction is unimolecular with respect to the palladium(II)-peptide complex. The cleavage is regioselective. In all the aforementioned dipeptides and in the tripeptide AcGly-His-Gly only the amide bond involving the carboxylic group of histidine is cleaved; the amide bond involving the amino group of histidine is not cleaved. When the carboxylic group of histidine is free, as in AcGly-His, cis-[Pd(en)(H2O)2]2+ does not effect hydrolysis. Lability of palladium(II) complexes and the acidic solution make possible a modest turnover in hydrolysis; the catalyst can cleave several equivalents of the dipeptide. The dipeptides AcHis-Aa, and also one product of their cleavage, AcHis, exist free and bound to the catalyst. They form similar palladium(II) complexes, five types of which are distinguishable by 1H NMR spectroscopy. The other products of cleavage, the amino acids Aa, exist free and in chelate complexes cis-[Pd(en)(N,O-Aa)]+. Partial binding of the catalyst to the peptide and to its cleavage products gives rise to an extended and complex equilibrium. Increase in pH favors catalytically-inactive palladium-(II)-peptide complexes, inhibits their conversion into catalytically-active complexes, and lowers the observed rate constant for hydrolysis. Because the equilibria are reversible, even the peptide bound in inactive complexes eventually becomes hydrolyzed. When palladium is removed as a diethyldithiocarbamate complex, the equilibria are abolished and only ethylenediamine, AcHis, and Aa remain. The rate constant for cleavage decreases as the steric bulk of the amino acid Aa increases and as intrapeptide hydrogen bonds mediated by water restrict the access of the palladium-(II) catalyst to the His-Aa bond. This hydrogen bonding is possible only when the amino acid Aa contains a hydroxyl group in a flexible side chain, as in Ser and Thr. The intrapeptide hydrogen bonding is impossible when a hydroxyl group is held relatively rigidly, as in Tyr, and, of course, when the hydroxyl group is absent, as in the other four amino acids. The kinetic effects of steric bulk and of specific hydrogen bonding may allow sequence selectivity in cleavage of peptides with palladium(II) complexes. This study points the way toward artificial metallopeptidases, coordination complexes with enzyme-like properties.
- Parac, Tatjana N.,Kosti?, Nenad M.
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- Cosmetic composition containing DOPA derivatives
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A composition for topical application to human hair or skin contains a chemical analogue of dihydroxyphenyl alanine (DOPA). This chemical analogue can be absorbed by skin or by a hair follicle and metabolised in-vivo, thus leading to the formation of melanin in skin or to the growth of melanin-pigmented hair. Consequently the composition can give controlled skin darkening to mimic sun-induced tanning or can bring about the growth of dar hair in place of the grey or white hair.
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- Cosmestic composition
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A composition suitable for topical application to mammalian skin and hair for inducing, maintaining or increasing hair growth comprises a hair growth promoter chosen from glutamic acid derivatives and salts thereof. The composition preferably also comprises an activity enhancer which may be chosen from hair growth stimulants, penetration enhancers and cationic polymers.
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- Hair growth composition containing citric acid esters
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Triesters of citric acid are used for inducing, maintaining or increasing hair growth. Compositions for topical application to mammalian hair or scalp comprise an effective amount of from 1% to 99% by weight of an ester of citric acid having the structure (1): where, R1, R2 and R3 each independently represent a branched or unbranched alkyl, alkenyl, aryl, alkylaryl or arylalkyl group, each said group having from 1 to 18 carbon atoms, R4 represents -H, or a branched or unbranched saturated or unsaturated acyl, alkyl, aryl, alkylaryl or aylalkyl group having from 1 to 18 carbon atoms, in the presence of a cosmetically acceptable vehicle for the citric acid ester and in the absence of solid absorbent for the ester;, said effective amount of said ester being sufficient to increase hair growth in the rat, when said composition is applied topically thereto over a period of no more than three months, by at least 10% more than that obtainable using a control composition from which the said ester has been omitted, in accordance with the Rat Hair Growth Test.
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- Acetylation under ultrasonic conditions: Convenient preparation of N-acetylamino acids
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An efficient and simple method of preparation of acetylamino acids from amino acids under ultrasonic conditions is described. The reactions proceed without racemization and the yields are almost quantitative.
- Veera Reddy,Ravindranath
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p. 257 - 264
(2007/10/02)
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