Conformation of cyclic peptides. VIII. Cyclic hexapeptides containing the L-pro-D-phe sequence

Kopple, Kenneth D.; Schamper, Thomas J.; Go, Anita

doi:10.1021/ja00815a046

Cited by 67 publications

(35 citation statements)

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“…While in chloroform and hexafluoroisopropanol both L-Pro-D-Phe sequences are P-folded, in DMSO or water, cis peptide linkages are found in L-Ala-L-Pro sequences. 67 The crystal structure of the hydrated cyclopeptide68 is an all-trans folded conformation in which the intramolecular i + 3 -i hydrogen bonds are not likely retained, being substituted by solute-water interactions. However, the folded conformation of the L-Pro-D-Phe sequences is not considerably different from that of a "standard" PII-bend.…”

Section: All-trans B-folded Conformationsmentioning

confidence: 99%

Experimental investigations on the backbone folding of proline‐containing model tripeptides

Boussard

Marraud

Aubry³

1979

Biopolymers

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Section: All-trans B-folded Conformationsmentioning

confidence: 99%

Experimental investigations on the backbone folding of proline‐containing model tripeptides

Boussard

Marraud

Aubry³

1979

Biopolymers

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“…Furthermore, the NH-C, coupling constant for the valine residue'in hydrocarbon solution is significantly larger than that in aqueous solution, and the resonances are somewhat upfield from those normally reported for random coil conformations, suggesting a distorted geometry. Hydrogen-bonds often shift peaks downfield, but the relative upfield shift reported here could be due to restricted orientation of the valine amide proton with respect to the peptide bond (8).…”

Section: Resultsmentioning

confidence: 65%

Conformation of an oligopeptide in phospholipid vesicles.

Wallace¹,

Blout²

1979

Proc. Natl. Acad. Sci. U.S.A.

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To demonstrate a method by which the conformation of membrane proteins may be determined spectroscopically in model membranes, we determined the structure of a hydrophobic oligopeptide, t-butyloxycarbonylprolylleucylvalylmethyl ester, in phospholipid vesicles by nuclear magnetic resonance, circular dichroism, and infrared spectroscopy. 13C nuclear magnetic resonance and circular dichroism techniques demonstrated that the conformation of this peptide in linear hydrocarbon solutions was essentially identical to its conformation in lipid vesicles. IH nuclear magnetic resonance and infrared spectroscopy of the peptide in hydrocarbon solution then provided additional high-resolution information concerning the structure of the peptide as found in the hydrophobic portion of the lipid bilayer. The conformation of this peptide in hydrophobic media differs from its structure in hydrophilic solvents, not only in bond angles and the proportion of cis/ trans isomers about the X-proline bond, but also in its intermolecular associations.The organization and biological activity of peptides and proteins in membranes is dependent upon the conformation they assume in a hydrophobic milieu. Clearly, the hydrocarbon chains of phospholipids present a very different structural matrix from water for the solvation of proteins. It might reasonably be expected that amino acid residues would assume different conformations in hydrophobic media. Diffraction studies of ordered two-dimensional arrays of proteins in membrane systems, such as the purple membrane of Halobacterium halobium (1), have provided some low-resolution information on the structure of membrane proteins. However; techniques that do not rely on the availability of ordered arrays of membrane proteins would be more generally useful. NMR spectroscopy has the potential for determining some bond angles between different portions of the peptide chain and the presence of inter-or intramolecular hydrogen bonds. Supplementary information at the level of gross secondary structure may be obtained from circular dichroism (CD) measurements. This work demonstrates the utility of such techniques for determining the structure of an oligopeptide in phospholipid vesicles.There are a number of problems, however, inherent in NMR studies of peptide structures in vesicles. First, the total peptide concentration must be relatively low in these samples in order to maintain the integrity of the lipid bilayer. Even with highsensitivity instruments, peptide signals are difficult to observe against the more abundant lipid background unless the compound is selectively enriched with 13C-labeled amino acids. Such enrichment may be useful for examining specific regions of large molecules; for example, studies of the orientation of gramicidin channels in lipid vesicles with '3C-enriched labels (unpublished data), but this method is, in general, not feasible for entire protein molecules. Furthermore, lipid resonances may obscure peptide resonances, especially in proton NMR, unless 100% perdeuterated l...

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“…For the fragment condensation and cyclization steps we have employed azide (7) or diphenylphosphoryl azide (DPPA) (8,9) coupling procedures. For the fragment condensation and cyclization steps we have employed azide (7) or diphenylphosphoryl azide (DPPA) (8,9) coupling procedures.…”

Section: Synthesesmentioning

confidence: 99%

Synthesis and backbone conformations of cyclic hexapeptides cyclo‐(Xxx‐Pro‐D‐Gln)₂

Kopple

Parameswaran

1983

International Journal of Peptide and Protein Research

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Conformation of cyclic peptides. VIII. Cyclic hexapeptides containing the L-pro-D-phe sequence

Cited by 67 publications

References 2 publications

Experimental investigations on the backbone folding of proline‐containing model tripeptides

Experimental investigations on the backbone folding of proline‐containing model tripeptides

Conformation of an oligopeptide in phospholipid vesicles.

Synthesis and backbone conformations of cyclic hexapeptides cyclo‐(Xxx‐Pro‐D‐Gln)₂

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Conformation of cyclic peptides. VIII. Cyclic hexapeptides containing the L-pro-D-phe sequence

Cited by 67 publications

References 2 publications

Experimental investigations on the backbone folding of proline‐containing model tripeptides

Experimental investigations on the backbone folding of proline‐containing model tripeptides

Conformation of an oligopeptide in phospholipid vesicles.

Synthesis and backbone conformations of cyclic hexapeptides cyclo‐(Xxx‐Pro‐D‐Gln)2

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Synthesis and backbone conformations of cyclic hexapeptides cyclo‐(Xxx‐Pro‐D‐Gln)₂