Structure and molecular conformation of tert-butoxycarbonyl-L-prolyl-D-prolyl-L-prolyl-D-proline, C25H38N4O7, a tetraproline derivative with alternating configurations

Colapietro, Marcello; Santis, P. De; Nocilli, F.; Palleschi, A; Spagna, R.

doi:10.1107/s0108270185003006

Cited by 3 publications

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“…(iv) The ϕ , ψ conformation is strongly (≈9 : 1) biased in favor of the semi ‐extended [poly‐(Pro) n ] over the α ‐helix structure. Subsequently, only a few crystal structures of this type of peptides were reported . In general, the results fit nicely with those listed earlier.…”

Section: Introductionsupporting

confidence: 83%

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

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et al. 2014

J. Pept. Sci.

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In this article, we review the relevant results obtained during almost 60 years of research on a specific aspect of stereochemistry, namely handedness preference and switches between right-handed and left-handed helical peptide structures generated by protein amino acids or appropriately designed, side-chain modified analogs. In particular, we present and discuss here experimental and theoretical data on three categories of those screw-sense issues: (i) right-handed/left-handed α-helix transitions underwent by peptides rich in Asp, specific Asp β-esters, and Asn; (ii) comparison of the preferred conformations adopted by helical host-guest peptide series, each characterized by an amino acid residue (e.g. Ile or its diastereomer aIle) endowed with two chiral centers in its chemical structure; and (iii) right-handed (type I)/left-handed (type II) poly-(Pro)n helix transitions monitored for peptides rich in Pro itself or its analogs with a pyrrolidine ring substitution, particularly at the biologically important position 4. The unique modular and chiral properties of peptides, combined with their relatively easy synthesis, the chance to shape them into the desired conformation, and the enormous chemical diversity of their coded and non-coded α-amino acid building blocks, offer a huge opportunity to structural chemists for applications to bioscience and nanoscience problems.

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Section: Introductionsupporting

confidence: 83%

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

Crisma

Zotti

Formaggio³

et al. 2014

J. Pept. Sci.

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Cyclo(D‐Pro‐L‐Pro‐D‐Pro‐L‐Pro): Structural properties and cis/trans isomerization of the cyclotetrapeptide backbone

et al. 1989

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Ulm, Federal Republic of Gennany SynopsisCombinations of L-and D-proline residues are useful compounds for finding new structures and properties of cyclic peptides. This is demonstrated with one striking example, the cyclic tetrapep-For this molecule composed of strictly alternating D-and L-configurated residues, a highly symmetrical structure is expected, which should be an optically inactive meso-form. Cyclization of the enantiomeric pure linear precursor D-P~o-L-P~o-D-P~o-L-P~o, however, yields a racemic mixture of two enantiomeric cyclotetrapeptides, both with twofold symmetry and a cis-trans-cis-trans sequence of the peptide bonds. Remarkably, this formation of a racemate was not caused by racemization, but by &/trans isomerization of all peptide bonds in the ring. This procans may occur in the,linear precursor during the ring formation (cyclization of conformers with trans-cis-trans or cis-trans-cis arrangement of the amide bonds) as well as in the enantiomeric pure cyclic tetrapeptide at higher temperature. In the latter case, an all& structure should exist as the intermediate, which can form a cis-truns-cis-truns sequence in two equivalent ways, leading finally to two enantiomeric cyclotetrapeptides. In the first one, the cis peptide bonds are attributed to the L-residues and the trans peptide bonds to the &residues; in the second one, the cis bonds belong to the D and the trans bonds to the bresidues. The mixture of these two enantiomers does not crystallize in the racemic form, but in enantiomeric pure separate crystals. The structural properties could be proved by 'H-and 13C-nmr spectroscopy and x-ray analysis. The cis/truns isomerization process was confirmed by optical rotation measurements and CD spectroscopy, as well as DREIDING model studies. Calorimetric measurements in the solid state suggest the existence of the expected all-cis intermediate. The backbone conformation of the 12-membered medium-sized ring shows only slight deviations-up to 6"-from the planarity of the peptide bonds. On the other hand, the four pyrrolidine rings show different types of puckering of the C, or the C, atoms.

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Structure and stability of the Boc(D‐Pro‐L‐Pro)₂OCH₃ Na⁺ complex: A model of poly(D,L‐proline), an alkali ion channel across membranes

et al. 1989

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In order to elucidate the molecular mechanisms of alkali ions conduction of poly(D,L-proline), which shows the typical behavior of an ion channel across membranes, conformations of the tetrameric derivative Boc(D-Pro-L-Pro)2OCH3 in solution, in the presence of the Na+ ion, were investigated by CD and nmr spectroscopy. Both theoretical and experimental data indicate the formation in solution of a monomeric complex between the tetramer, in the all-trans conformation, and the cation. The results allow to confirm the channel model, previously proposed on the phenomenological behavior of poly(D,L-proline) in membranes.

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Structure and molecular conformation of tert-butoxycarbonyl-L-prolyl-D-prolyl-L-prolyl-D-proline, C25H38N4O7, a tetraproline derivative with alternating configurations

Cited by 3 publications

References 2 publications

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

Cyclo(D‐Pro‐L‐Pro‐D‐Pro‐L‐Pro): Structural properties and cis/trans isomerization of the cyclotetrapeptide backbone

Structure and stability of the Boc(D‐Pro‐L‐Pro)₂OCH₃ Na⁺ complex: A model of poly(D,L‐proline), an alkali ion channel across membranes

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Structure and molecular conformation of tert-butoxycarbonyl-L-prolyl-D-prolyl-L-prolyl-D-proline, C25H38N4O7, a tetraproline derivative with alternating configurations

Cited by 3 publications

References 2 publications

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

Handedness preference and switching of peptide helices. Part I: Helices based on protein amino acids

Cyclo(D‐Pro‐L‐Pro‐D‐Pro‐L‐Pro): Structural properties and cis/trans isomerization of the cyclotetrapeptide backbone

Structure and stability of the Boc(D‐Pro‐L‐Pro)2OCH3 Na+ complex: A model of poly(D,L‐proline), an alkali ion channel across membranes

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Structure and stability of the Boc(D‐Pro‐L‐Pro)₂OCH₃ Na⁺ complex: A model of poly(D,L‐proline), an alkali ion channel across membranes