Synthesis and structural characterization of bioactive peptide conjugates using thioether linkage approaches.
Applications of cysteine-insertion and thioether linkage approaches to the preparation of a number of bioactive peptide conjugates are reported. Peptides containing epitopes from (i) herpes simplex virus type 1 glycoprotein D, (ii) a specific N-terminal beta-amyloid epitope recognized by therapeutically active antibodies, and (iii) a GnRH-III peptide from sea lamprey with antitumour activity, were elongated with Cys residues and attached to a chloroacetylated tetratuftsin derivative carrier via a thioether linkage either directly, or by insertion of a spacer. The structures and molecular homogeneity of all the peptide conjugates were ascertained by HPLC, MALDI and electrospray mass spectrometry. The use of a spacer such as an oligoglycine or GFLG-tetrapeptide gave an increased yield in the conjugation reaction and enhanced reaction rates. In the formation of cysteinyl-thioether linkages, it was found that the position of flanking Cys residues markedly influenced the conjugation reaction and the formation of intermolecular epitope disulfide-dimers. C-terminal Cys residues gave thioether conjugates with significantly diminished epitope-dimerization, while Cys at the N-terminal caused rapid disulfide-dimerization, thereby preventing efficient conjugation.
Mezö
Gábor
G
Research Group of Peptide Chemistry, Hungarian Academy of Sciences, Eötvös L. University, Budapest, Hungary. mezo@szerves.chem.elte.hu
Manea
Marilena
M
Jakab
Annamária
A
Kapuvári
Bence
B
Bösze
Szilvia
S
Schlosser
Gitta
G
Przybylski
Michael
M
Hudecz
Ferenc
F
D000085:Acetates; D000595:Amino Acid Sequence; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000737:chemistry; D000939:Epitopes / Q000737:chemistry*; D007987:Gonadotropin-Releasing Hormone / Q000737:chemistry; D009842:Oligopeptides / Q000138:chemical synthesis; D010084:Oxidation-Reduction; D010455:Peptides / Q000138:chemical synthesis*; D013440:Sulfides / Q000138:chemical synthesis*; D014405:Tuftsin / Q000737:chemistry
D000085:Acetates; D000939:Epitopes; D009842:Oligopeptides; D010455:Peptides; D013440:Sulfides; D007987:Gonadotropin-Releasing Hormone; C006972:chloroacetic acid; D003545:Cysteine; D014405:Tuftsin