N-hydroxy-amide analogues of MHC-class I peptide ligands with nanomolar binding affinities

Abstract

A novel class of major histocompatibility complex class I (MHC-I) ligands containing an N-hydroxyamide bond was designed on the basis of the natural epitope SIINFEKL, and synthesized on solid phase. The capacity of these compounds to bind to the MHC-I molecule H-2Kb and to induce T cell responses was analysed in comparison with the corresponding glycine containing variant of SIINFEKL. Binding to the MHC molecule was diminished by the N-hydroxy group at positions 2 and 3 of the oligomer and improved in the case of positions 4, 5, 6 and 7. No change was seen for position 1. The efficacy of T cell stimulation was strongly reduced by the modification of all positions except for position 1. A complete loss of activity was found for the N-hydroxy variant in positions 4 and 6. N-Hydroxy amide-containing peptides displayed an enhanced stability to enzymatic degradation. This new class of MHC ligand can become instrumental as immunomodulatory reagent in various disease situations.

A New Generation of Melan-A/MART-1 Peptides That Fulfill Both Increased Immunogenicity and High Resistance to Biodegradation: Implication for Molecular Anti-Melanoma Immunotherapy

“…Melan-A nonamer and decamers show marked quantitative and qualitative differences in their degradation properties. However, the differences in the half-life of the Melan-A peptides could not be explained solely by differences in peptide length, because the decamer Melan-A 26 -35 E26A (AAAGIGILTV) displayed a kinetic of degradation (t 1/2 , 15 min; data not shown) closer to that of Melan-A [27][28][29][30][31][32][33][34][35] than that of the two Melan-A decamers. Thus, the nature of the first amino-terminal residues that greatly influence peptide susceptibility to amino-terminal degradation (37) seems to govern the kinetics of degradation of the Melan-A peptides.…”

“…The reduced bond ⌿(CH 2 -NH) was formed by the reductive alkylation of a free amino group with an F-moc-protected preformed amino aldehyde (31). N-terminal hydroxypeptides were synthesized following a previously described procedure (32). The retro-inverso bond ⌿(NH-CO) was obtained by replacement of two sequential amino acids with an (R,S)-2-substituted malonate derivative and a gem-diaminoalkyl residue (for example, the gem-diaminoalkyl residue corresponding to glutamic acid side chain and 2-substituted malonic acid corresponding to leucine side chain (2(R,S)-isobutylmalonic acid) were used for the synthesis of [⌿ 1-2 (NH-CO)]-Melan-A 26 -35 A27L) (33,34).…”

“…1B, the main amino-terminal degradation products of the Melan-A 27-35 nonamer (AGIGILTV and GIGILTV) were more abundant than those of the Melan-A 26 -35 decamers. This observation suggests that the Melan-A [27][28][29][30][31][32][33][34][35] nonamer is degraded more rapidly by amino-peptidases than the Melan-A decamers. This sensitivity could explain the very short half-life of the nonameric peptide.…”

“…We used the Melan-A 26 -35 A27L peptide as the starting sequence because of its enhanced immunogenicity (10) (35), NMeaa (NMeE1), a pyro-glutamic acid (pE1), N-acetylated E, or an N-hydroxylated glycine (NOHG1) (32). Modification of leucine residue at position 2 (L2) was achieved by replacing it with methylated aa (␣MeL2, NMeL2) or dL2.…”

“…A superagonist variant of the nonameric Melan-A [27][28][29][30][31][32][33][34][35] peptide has been shown to elicit an enhanced anti-melanoma CD8 ϩ CTL response (9). We have recently undertaken clinical trials of peptide vaccination using the decameric analog Melan-A 26 -35 A27L (ELAGIGILTV).…”