- Selenazolidine: A selenium containing proline surrogate in peptide science
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In the search for new peptide ligands containing selenium in their sequences, we investigated l-4-selenazolidine-carboxylic acid (selenazolidine, Sez) as a proline analog with the chalcogen atom in the γ-position of the ring. In contrast to proteinogenic selenocysteine (Sec) and selenomethionine (SeMet), the incorporation within a peptide sequence of such a non-natural amino acid has never been studied. There is thus a great interest in increasing the possibility of selenium insertion within peptides, especially for sequences that do not possess a sulfur containing amino acid (Cys or Met), by offering other selenated residues suitable for peptide synthesis protocols. Herein, we have evaluated selenazolidine in Boc/Bzl and Fmoc/tBu strategies through the synthesis of a model tripeptide, both in solution and on a solid support. Special attention was paid to the stability of the Sez residue in basic conditions. Thus, generic protocols have been optimized to synthesize Sez-containing peptides, through the use of an Fmoc-Xxx-Sez-OH dipeptide unit. As an example, a new analog of the vasopressin receptor-1A antagonist was prepared, in which Pro was replaced with Sez [3-(4-hydroxyphenyl)-propionyl-d-Tyr(Me)-Phe-Gln-Asn-Arg-Sez-Arg-NH2]. Both proline and such pseudo-proline containing peptides exhibited similar pharmacological properties and endopeptidase stabilities indicating that the presence of the selenium atom has minimal functional effects. Taking into account the straightforward handling of Sez as a dipeptide building block in a conventional Fmoc/tBu SPPS strategy, this result suggested a wide range of potential uses of the Sez amino acid in peptide chemistry, for instance as a viable proline surrogate as well as a selenium probe, complementary to Sec and SeMet, for NMR and mass spectrometry analytical purposes.
- Cordeau,Cantel,Gagne,Lebrun,Martinez,Subra,Enjalbal
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- Synthesis of selenocystine derivatives from cystine by applying the transformation reaction from disulfides to diselenides
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A stepwise conversion of a disulfide (SS) to a diselenide (SeSe) bond through the corresponding iodide intermediate was implemented and was applied to the synthesis of selenocystamine and l-selenocystine derivatives from cystamine and l-cystine, respectively, in moderate yields.
- Iwaoka, Michio,Haraki, Chie,Ooka, Ryuta,Miyamoto, Masahiro,Sugiyama, Ai,Kohara, Yumiko,Isozumi, Noriyoshi
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- Reactivity of Selenocystine and Tellurocystine: Structure and Antioxidant Activity of the Derivatives
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l-Selenocystine (5) and l-tellurocystine (6) have been prepared and the reactivity of these amino acids, i.e., oxidation of 5 and 6, has been performed at various pH values. Hydrogen peroxide was used as an oxidant and it was treated with 5 and 6 in excess in acidic and basic media. Compound 5, upon oxidation, afforded SeIV and SeVI products. Selenocysteic acid [HO3SeCH2CH(NH2)COOH] 9, a novel SeVI compound, was isolated and characterised by single-crystal X-ray diffraction studies. In contrast, l-tellurocystine, upon oxidation with H2O2, afforded TeII and TeIV products. Zwitterionic organotellurolate(IV), [TeCl3CH2CH(NH3)COOH] 13, was isolated and characterised by NMR and IR spectroscopy, mass spectrometry and elemental analysis. Compound 13 crystallizes in an orthorhombic space group. l-Tellurocystine, when reduced with NaBH4, produced the desired tellurolate intermediate, which was trapped with bromoacetic acid. Furthermore, l- and d-tellurocysteine derivatives, [(RTeCH2CH(NH2)COOH) R=phenyl, substituted phenyl and naphthyl (24–39)] were synthesised and evaluated for their glutathione peroxidase (GPx)-like activities. The results show that l-tellurocysteine derivatives have higher activity than their D-tellurocysteine analogues. DFT calculations for l-tellurocysteine derivatives provided information about the bond lengths and bond angles. This study reveals that the introduction of naphthyl substituents (35–38) leads to twisted conformation of the amino acid derivatives.
- Satheeshkumar, Kandhan,Raju, Saravanan,Singh, Harkesh B.,Butcher, Ray J.
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- Selenium and sulfur in exchange reactions: A comparative study
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Cysteamine reduces selenocystamine to form hemiselenocystamine and then cystamine. The rate constants are k1 = 1.3 × 105 M-1 s-1; k-1 = 2.6 × 107 M-1 s-1; k2 = 11 M-1 s-1; and k-2 = 1.4 × 103 M-1 s-1, respectively. Rate constants for reactions of cysteine/selenocystine are similar. Reaction rates of selenium as a nucle'phile and as an electrophile are 2-3 and 4 orders of magnitude higher, respectively, than those of sulfur. Sulfides and selenides are comparable as leaving groups.
- Steinmann, Daniel,Nauser, Thomas,Koppenol, Willem H.
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- Studies on the reaction between reduced riboflavin and selenocystine
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Selenocysteine (Sec) is a crucial component of mammalian thioredoxin reductase (TrxR) where it serves as a nucleophile for disulfide bond rupture in thioredoxin (Trx). Generation of the reduced state of Sec in TrxR requires consecutive two electron transfer steps, namely: (i) from NADPH to flavin adenine dinucleotide, (ii) from reduced flavin to the disulfide bond Cys59-S-S-Cys64, and finally (iii) from Cys59 and Cys64 to the selenosulfide bond Cys497-S-Se-Sec498. In this work, we studied the reaction between reduced riboflavin (RibH2) and selenocystine (Sec-Sec), an oxidized form of Sec. The interaction between RibH2 and Sec-Sec proceeded relatively slowly in comparison with its reverse reaction, that is, reduction of riboflavin (Rib) by Sec. The rate constant for the reaction between RibH2 and Sec-Sec was (7.9?±?0.1)?×?10?2?M?1 s?1 (pH 7.0, 25.0°C). The reaction between Rib and Sec proceeded via two steps, namely, a rapid reversible binding of Rib to Sec having a protonated selenol group to form a Sec-Rib complex, followed by nucleophilic attack of Sec-Rib by a second Sec molecule harboring a deprotonated selenol group. The equilibrium constant for the overall reduction process of Rib by Sec is (1.2?±?0.1)?×?106?M?1 (25.0°C). The finding that the interaction of RibH2 with oxidized selenol is reversible with its equilibrium favored toward the reverse reaction provides an additional explanation for the exceptional mechanism of the mammalian Trx/TrxR system involving transient reduction of a disulfide bond.
- Dereven'kov, Ilia A.,Makarov, Sergei V.,Molodtsov, Pavel A.,Makarova, Anna S.
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p. 146 - 153
(2020/09/21)
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- Diphosphoric acid compounds, and preparation method and application thereof
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The invention discloses compounds disclosed as Formula II. In the Formula II, R is disclosed in the specification, wherein R1 is H, OH or halogen; R2 is disclosed in the specification, n1=0-10, n2=0-10, and n3=0-10; Ar is aryl, arylidene, R99-substituted aryl or R99-substituted arylidene; at least one of R3, R4, R5 and R6 is selenium or sulfur atom, and the rest is carbon or nitrogen atom; and R3, R4, R5 and R6 are connected through a single bond or double bond. As for old patients with osteoporosis, the compounds can keep the osteocyte bone formation and bone destroy at an ideal dynamic balance.
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Paragraph 0137; 0159
(2016/10/31)
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- Preparation method for L-selenocysteine
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The invention belongs to the field of chemical synthesis, and concretely relates to a synthetic method for L-selenocysteine. The method comprises the following steps: a, chloridizing L-serine hydrochloride to obtain 3-chloro-L-alanine hydrochloride; b, performing seleno-reaction of 3-chloro-L-alanine hydrochloride prepared by step a under alkaline condition to obtain L-selenocystine; and c, performing reduction reaction of L-selenocystine to obtain L-selenocysteine. The method has simple steps, high yield, low cost, and good application prospect.
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Paragraph 0030; 0031
(2016/12/26)
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- Role of substrate reactivity in the glutathione peroxidase (gpx) activity of selenocystine
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Selenocystine (CysSeSeCys), a diselenide, exhibits glutathione peroxidase (GPx) activity, where it catalyses the reduction of hydroperoxides using a thiol co-factor. To understand the relative reactivity of the two substrates, enzymekinetic parameters, i.e., the turnover number (kcat) and the relative reactivity parameters toward thiol (φG) and hydroperoxide (H), were determined by applying Dalziel kinetics for a bi-substrate model in the presence of hydrogen peroxide (H2O 2), t-butyl hydroperoxide, or α-cumyl hydroperoxide and glutathione or dithiothreitol (DTTred). The intermediates formed during the reaction of CysSeSeCys with H2O2 and DTT red were characterized by 77SeNMR spectroscopy. Ab initio calculation at HF/6-31G(d) indicated that the reactions with H2O2 are exothermic, while those with DTTred are endothermic. Based on these studies, the GPx activity of CysSeSeCys is likely to be initiated by the reaction with hydroperoxide and in the catalytic cycle, the reaction with thiol is the rate-determining step.
- Singh, Beena G.,Bag, Partha P.,Kumakura, Fumio,Iwaoka, Michio,Priyadarsini, K. Indira.
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supporting information; experimental part
p. 703 - 708
(2010/08/08)
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- Internally stabilized selenocysteine derivatives: Syntheses, 77Se NMR and biomimetic studies
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Selenocystine ([Sec]2) and aryl-substituted selenocysteine (Sec) derivatives are synthesized, starting from commercially available amino acid L-serine. These compounds are characterized by a number of analytical techniques such as NMR (1H, 13C and 77Se) and TOF mass spectroscopy. This study reveals that the introduction of amino/imino substituents capable of interacting with selenium may stabilize the Sec derivatives. This study further suggests that the oxidation-elimination reactions in Sec derivatives could be used for the generation of biologically active selenols having internally stabilizing substituents. The Royal Society of Chemistry 2005.
- Phadnis, Prasad P.,Mugesh
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p. 2476 - 2481
(2007/10/03)
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- Synthesis of a selenocysteine-containing peptide by native chemical ligation
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(equation presented) A new method for the synthesis of selenocysteine derivatives and selenocysteine-containing peptides is described. Fmoc-Se-p-methoxybenzylselenocysteine (1) was prepared and used for solid-phase synthesis of peptides with an N-terminal unprotected selenocysteine. Subsequent native chemical ligation with a peptide thioester provided a 17-mer that corresponds to the C-terminus of ribonucleotide reductase with selenocysteine in place of cysteine.
- Gieselman, Matt D.,Xie, Lili,Van Der Donk, Wilfred A.
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p. 1331 - 1334
(2007/10/03)
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- Selenazolidines as novel organoselenium delivery agents
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Two new classes of selenazolidine-4(R)-carboxylic acids (2-oxo and 2-methyl-SCAs) were synthesized and characterized. Both were designed as latent forms of selenocysteine, intended to provide a chemically superior delivery form for selenium. The prodrugs may be clinically useful when selenium supplementation at supranutritional levels is indicated, such as in cancer chemoprevention.
- Xie, Yang,Short, Megan D.,Cassidy, Pamela B.,Roberts, Jeanette C.
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p. 2911 - 2915
(2007/10/03)
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- Synthesis of L-selenocystine, L-[77Se]selenocystine and L-tellurocystine
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Synthetic routes for the synthesis of stable isotope labelled amino acids which contain either a selenium or a tellurium atom have been explored. L-Selenocystine, L-[77Se]selenocystine and L-tellurocystine have been constructed in four steps from commercially available methyl (2S)-2-[(tert-butoxycarbonyl)amino]-3-hydroxypropionate. The sequence of reactions has been successfully scaled up giving significant quantities of the chalcogen based amino acids in fair to good overall yield. Copyright 1997 by the Royal Society of Chemistry.
- Stocking, Emily M.,Schwarz, Jessie N.,Senn, Hans,Salzmann, Michael,Silks, Louis A.
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p. 2443 - 2447
(2007/10/03)
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- CONCISE SYNTHESES OF L-SELENOMETHIONINE AND OF L-SELENOCYSTINE USING RADICAL CHAIN REACTIONS
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L-Selenomethionine and L-selenocystine were prepared in high overall yields from protected L-glutamic and L-aspartic acid derivatives respectively.Irradiation of the mixed anhydrides (esters) derived from 4 (e.g. 15) in the presence of dimethyldiselenide provided the protected L-selenomethionine 16 directly.We have shown that triselenocyanide Se3(CN)2 can serve as an efficient selenocyanating agent for radicals; the selenocyanide group is a good precursor for the diselenide moiety of L-selenocystine.
- Barton, Derek H. R.,Bridon, Dominique,Herve, Yolande,Potier, Pierre,Thierry, Josiane,Zard, Samir Z.
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p. 4983 - 4990
(2007/10/02)
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- Synthesis of Selenocystine and Selenohomocystine with O-Acetylhomoserine Sulfhydrylase
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We descibe here the synthesis of selenium amino acids with O-acetylhomoserine sulfhydrylase, partially purified from baker's yeast.The enzyme was found to catalyze the synthesis of L-selenocystine and L-selenohomocystine from Na2Se2 with the corresponding acetyl-derivatives of serine and homoserine, respectively.L-Serine-O-sulfate also serves as a substrate of the β-replacement reaction.Na2Se2 is less efficient as a substituent donor than the physiological substrate, NaHS, and inhibits the enzyme at high concentrations.Therefore, limited amounts of Na2Se2 were added to the reaction mixture to increase the yield (50 to 60percent).This provides a facile method to produce optically active selenocystine and selenohomocystine.
- Chocat, Patrick,Esaki, Nobuyoshi,Tanaka, Hidehiko,Soda, Kenji
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p. 1143 - 1150
(2007/10/02)
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