- Cysteine-based fluorescence "turn-on" sensors for Cu2+and Ag+
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We designed and synthesized twometal ion binding molecules 3a and 3b based on cysteine. In 3a, pyrene is used as a fluorescent probe, while 3b contains tryptophan, which acts as a fluorescent probe as well as facilitates metal ion binding. Detailed spectroscopic, calorimetric, microscopic and computational studies revealed the binding mode and the plausible structures of the complexes.
- Haridas,Praveen Kumar,Suresh, Cherumuttathu H.
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- Asymmetric synthesis of S-alkyl-substituted (R)-cysteines via a chiral NiII complex of the Schiff's base of dehydroalanine with (S)-2-N-(N-benzylprolyl)aminobenzophenone
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An efficient procedure was developed for the asymmetric synthesis of S-alkyl derivatives of (R)-cysteine by nucleophilic addition of alkanethiols (BunSH, ButSH, or tert-C5H11SH) to the C=C bond of the dehydroalanine fragment in the Ni11 complex of the Schiff's base of Δ-Ala with (S)-2-N-(N-benzylprolyl)aminobenzophenone [(S)-BPB-Δ-Ala]Ni11. Under conditions of thermodynamic control of the reaction, the diastereomeric excess of the complexes with the (S,R)-configuration was 88 - 96%. After decomposition of the complexes, (R)-S-butylcysteine, (R)-S-tert-butylcysteine, and (R)-S-tert-pentylcysteine were isolated with an enantiomeric purity of >97%.
- Saghiyan,Geolchanyan,Djamgaryan,Vardapetyan,Tararov,Kuz'mina,Ikonnikov,Belokon',North
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- Asymmetric synthesis of β-lactams by intramolecular conjugate addition of serine and cysteine derivatives via memory of chirality
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– The 4-exo-trig cyclization of axially chiral enolates generated from L-serine and L-cysteine dervatives proceeded predominately over β-elimination to give chiral β-lactams with contiguous tri- and tetrasubstituted carbon centers in up to 96% ee. The key to smooth production of β-lactams is the use of Cs2CO3and CF3CH2OH as a base and a proton source, respectively. A strongly electron-withdrawing Michael acceptor in the substrates was also critical for high enantioselectivity of the β-lactam formation.
- Hyakutake, Ryuichi,Yoshimura, Tomoyuki,Ueda, Yoshihiro,Hayashi, Kazuhiro,Furuta, Takumi,Kawabata, Takeo
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p. 1128 - 1147
(2019/07/31)
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- Acylase I-catalyzed deacetylation of N-acetyl-L-cysteine and S-alkyl-N- acetyl-L-cysteines
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The aminoacylase that catalyzes the hydrolysis of N-acetyl-L-cysteine (NAC) was identified as acylase I after purification by column chromatography and electrophoretic analysis. Rat kidney cytosol was fractionated by ammonium sulfate precipitation, and the proteins were separated by ion-exchange column chromatography, gel-filtration column chromatography, and hydrophobic interaction column chromatography. Acylase activity with NAC and N-acetyl-L- methionine (NAM), a known substrate for acylase I, as substrates coeluted during all chromatographic steps. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the protein was purified to near homogeneity and had a subunit M(r) of 43 000, which is identical with the M(r) of acylase I from porcine kidney and bovine liver. n-Butylmalonic acid was a slow-binding inhibitor of acylase I and inhibited the deacetylation of NAC with a K(i) of 192 ± 27 μM. These results show that acylase I catalyzes the deacetylation of NAC. The acylase I-catalyzed deacetylation of a range of S-alkyl-N- acetyl-L-cysteines, their carbon and oxygen analogues, and the selenium analogue of NAM was also studied with porcine kidney acylase I. The specific activity of the acylase I-catalyzed deacetylation of these substrates was related to their calculated molar volumes and log P values. The S-alkyl-N- acetyl-L-cysteines with short (C0-C3) and unbranched S-alkyl substituents were good acylase I substrates, whereas the S-alkyl-N-acetyl-L-cysteines with long (>C3) and branched S-alkyl substituents were poor acylase I substrates. The carbon and oxygen analogues of S-methyl-N-acetyl-L-cysteine and the carbon analogue of S-ethyl-N-acetyl-L-cysteine were poor acylase I substrates, whereas the selenium analogue of NAM was a good acylase I substrate.
- Uttamsing, Vinita,Keller,Anders
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p. 800 - 809
(2007/10/03)
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