NMR analysis of a potent decapeptide agonist of human C5a anaphylatoxin

Abstract

A NMR investigation in H20, TFE and DMSO of a conformationally constrained, potent decapeptide agonist of human C5a, YSFKDMPLaR (C5a65‐74, Y65, F67, P71, d‐Ala73) showed that its N‐terminal region (YSFKD) exhibited an extended backbone conformation in H2O and a more twisted conformation in both TFE/H2O (30:70, v/v; referred to as TFE) and DMSO. The C‐terminal region (MPLaR) of the peptide adopted compact, turn‐like structures. In H2O, the C‐terminal region adopted a type II β‐turn or a distorted type V/II β‐turn involving residues PLaR. In the distorted type V/II β‐turn, Leu72 exhibited a conformation typical of a type V β‐turn, whereas D‐Ala73 exhibited a conformation typical of a type II β‐turn. The distorted type V/II β‐turn overlapped with an inverse γ‐turn involving residues MPL. In DMSO, the C‐terminal region had the analogous inverse y‐turn and the V/II γ‐turn found in H2O. In many of the DMSO structures, two inverse γ‐turns in the MPL and PLa positions formed a double‐inverse γ‐turn. None of the turns observed in H2O were present in TFE. However, in TFE, the PLa residues formed an inverse γ‐turn. Overall, the turn‐like structural motifs in the C‐terminal region of the peptide in both H2O and DMSO (but not in TFE) agreed with the biologically important conformations obtained earlier by the structure‐function analysis of a panel of C5a agonist peptides. These motifs may represent key structural elements important for C5a agonist activity and may be used to design the next generation of C5a agonist and antagonist analogues. © Munksgaard 1998.

A conformationally-biased, response-selective agonist of C5a acts as a molecular adjuvant by modulating antigen processing and presentation activities of human dendritic cells

“…However, we have developed a conformationally-biased, responseselective, decapeptide agonist of C5a, C5a 65-74 Y65,F67,P69, P71,D-Ala-73 (YSFKPMPLaR or EP54) that retains C5a-like immune stimulatory properties at the expense of C5a-like inflammatory properties via the engagement of neutrophils [10][11][12][13]. This bio-selectivity results from the unique conformational features expressed by EP54, which are well accommodated by C5a receptors (C5aR) expressed on antigen presenting cells such as DCs and macrophages, but not by C5aRs on neutrophils [14,15]. These conformational features also render EP54 stable to proteolysis by serum carboxypeptidases [16].…”

Structural characterization of peptide fragments from hCD81–LEL

“…The NMR spectroscopy for 1 was performed as described previously (16). Briefly, all high‐resolution 1D and 2D 1 H NMR experimental data were acquired on an 11.75T Varian UNITYplus spectrometer (Varian, Palo Alto, CA, USA), operating at 499.96 MHz for 1 H, with a 5‐mm triple‐resonance inverse detection probe.…”