Conformational analysis of hexapseudopeptides mimicking reverse turn structures induced by a modified (S)-proline. A combined spectroscopic and molecular dynamics investigation. Part 4

Balducci, Daniele; Bottoni, Andreà; Calvaresi, Matteo; Porzi, Gianni

doi:10.1080/00268970902845339

Cited by 2 publications

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“…This hydrogen bond would stabilize a classic b-turn between the carbonyl oxygen of residue i and the amide hydrogen of residue i + 3 as it is oen present in bioactive peptides. 31 In conformation B a hydrogen bond between the isoleucine NH and the carbonyl oxygen of tryptophan was modeled (Fig. 3).…”

Section: Andmentioning

confidence: 99%

Structure determination of the bioactive depsipeptide xenobactin from Xenorhabdus sp. PB30.3

et al. 2013

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A new hexadepsipeptide called xenobactin (1) was isolated from Xenorhabdus sp. PB30.3. Structure elucidation was performed after isolation by extensive 1D-and 2D-NMR experiments. To determine the absolute configuration of the amino acids, modifications of the advanced Marfey's method were applied avoiding racemization and additionally allowing the stereochemical assignment of tryptophan.Moreover, the three dimensional structure was modeled by ROE derived constraints and molecular dynamics runs. The major conformation was verified by comparison of the modeled and experimentally predicted hydrogen bonds. Moreover, bioactivity testing of 1 revealed good antiprotozoal activity against Plasmodium falciparum and a specific antibiotic activity against the Gram positive bacterium Micrococcus luteus, whereas no cytotoxicity could be observed.

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Section: Andmentioning

confidence: 99%

Structure determination of the bioactive depsipeptide xenobactin from Xenorhabdus sp. PB30.3

et al. 2013

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Stereocontrolled Synthesis of Unnatural Tetrapeptides Containing L‐Valine Units. Part 3

Balducci

Porzi

2011

Helvetica Chimica Acta

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The stereoselective synthesis of the new nonproteinogenic branched tetrapeptides 9a -9d and 15a,b, containing two l-valine units and unnatural a-amino acids, was accomplished starting from the chiral synthon 1a, a monolactim ether easily obtained from l-valine.Introduction. -The present communication is a continuation of our studies directed at the stereoselective synthesis of pseudopeptides with the objective that the unnatural peptides, as some natural ones, could exhibit biological activity with the advantage of proteolytic stability. The presence of a-alkyl a-amino acids may influence the conformation of these unnatural peptides altering their properties [3]. Thus, we have focused our attention towards new peptidomimetic structures containing nonproteinogenic a-alkylated a-amino acids (modified proline or aspartic acid) and l-valine units [4]. This communication is connected with previous articles which addressed the stereocontrolled synthesis of unnatural tetrapeptides, C-terminal at both ends of the chain, containing l-valine units [1] [2]. Here, we report a versatile and simple approach to the stereoselective synthesis of branched unnatural tetrapeptides containing two lvaline units, one 2-methyl-d-aspartic acid and one other a-amino acid. The latter aamino acid was either (2R)-2,4-diaminobutanoic acid (in 9a), its (2R)-2-methyl (i.e., disovaline; in 9b), or its (2S)-2-methyl derivative (i.e., l-isovaline; in 15a), or dornithine (in 9c), its 2-methyl (in 9d), or the corresponding 2-methyl-l derivative (in 15b).The synthetic strategy adopted in the stereocontrolled synthesis of the title pseudotetrapeptides is based on the experience already acquired in previous approaches [1] [2] [4] making use of the chiral monolactim ether 1a, easily obtained from l-valine [5]. Schçllkopfs strategy, aimed to the asymmetric synthesis of nonproteinogenic dipeptides, was based on the use of the bis-lactim ether which is subsequently converted to the corresponding monolactim derivative [6].

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Conformational analysis of hexapseudopeptides mimicking reverse turn structures induced by a modified (S)-proline. A combined spectroscopic and molecular dynamics investigation. Part 4

Cited by 2 publications

References 50 publications

Structure determination of the bioactive depsipeptide xenobactin from Xenorhabdus sp. PB30.3

Structure determination of the bioactive depsipeptide xenobactin from Xenorhabdus sp. PB30.3

Stereocontrolled Synthesis of Unnatural Tetrapeptides Containing L‐Valine Units. Part 3

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