TY - JOUR
T1 - Synthetic peptide vaccines: palmitoylation of peptide antigens by a thioester bond increases immunogenicity
AU - Beekman, N.J.C.M.
AU - Schaaper, W.M.M.
AU - Tesser, G.I.
AU - Dalsgaard, Kristian
AU - Kamstrup, Søren
AU - Langeveld, J.P.M.
AU - Boshuizen, R.S.
AU - Meloen, R.H.
PY - 1997
Y1 - 1997
N2 - Synthetic peptides have frequently been used to immunize animals. However, peptides less than about 20 to 30 amino acids long are poor immunogens. In general, to increase its immunogenicity, the presentation of the peptide should be improved, and molecular weight needs to be increased. Many attempts have been made to couple peptide immunogens to different carrier proteins [e.g. keyhole limper haemocyanin (KLH) or ovalbumin]. This leads to very complex structures, however. We used a controlled conjugation of a peptide to a single long-chain fatty acid like palmitic acid by a thioester or an amide bond. It was found that these S-palmitoylated peptides were much more immunogenic than N-palmitoylated peptides and at least similar to KLH-conjugated peptides with respect to appearance and magnitude of induced antibodies (canine parvovirus) or immunocastration effect (gonadotropin-releasing hormone). For chemical synthesis of thioesters, we established conditions for solution and solid-phase synthesis. In both phases, Cys(SBut) could only be deprotected efficiently using phosphines, and S-acylation was accomplished using standard coupling at pH 5. We speculate that, in vivo, the presence of an appropriate fatty acid chain, chemically linked through a labile thioester bond, greatly enhances immunogenicity, because it represents a favourable substrate for cleavage by cellular thioesterases in cells of the immune system.
AB - Synthetic peptides have frequently been used to immunize animals. However, peptides less than about 20 to 30 amino acids long are poor immunogens. In general, to increase its immunogenicity, the presentation of the peptide should be improved, and molecular weight needs to be increased. Many attempts have been made to couple peptide immunogens to different carrier proteins [e.g. keyhole limper haemocyanin (KLH) or ovalbumin]. This leads to very complex structures, however. We used a controlled conjugation of a peptide to a single long-chain fatty acid like palmitic acid by a thioester or an amide bond. It was found that these S-palmitoylated peptides were much more immunogenic than N-palmitoylated peptides and at least similar to KLH-conjugated peptides with respect to appearance and magnitude of induced antibodies (canine parvovirus) or immunocastration effect (gonadotropin-releasing hormone). For chemical synthesis of thioesters, we established conditions for solution and solid-phase synthesis. In both phases, Cys(SBut) could only be deprotected efficiently using phosphines, and S-acylation was accomplished using standard coupling at pH 5. We speculate that, in vivo, the presence of an appropriate fatty acid chain, chemically linked through a labile thioester bond, greatly enhances immunogenicity, because it represents a favourable substrate for cleavage by cellular thioesterases in cells of the immune system.
KW - synthetic peptide vaccine
KW - palmitoylation
KW - canine parvovirus
KW - GnRH
KW - thioester
KW - enhancement of immunogenicity
U2 - 10.1111/j.1399-3011.1997.tb01195.x
DO - 10.1111/j.1399-3011.1997.tb01195.x
M3 - Journal article
SN - 1397-002X
VL - 50
SP - 357
EP - 364
JO - Journal of Peptide Research
JF - Journal of Peptide Research
IS - 5
ER -