title: Stepwise transformation of a cholera toxin and a p24 (HIV-1) epitope into D-peptide analogs.
abstract: We have transformed two peptide epitopes into D-peptide analogs: VPGSQHIDS derived from cholera toxin recognized by the antibody TE33, and GATPQDLNTML from the HIV-1 capsid protein p24 recognized by the antibody CB4-1. The transformation process was performed by stepwise substitution of each single epitope position by all 19 D-amino acids and glycine followed by antibody binding studies and selection of one D-analog for further transformation. Thus, each transformation step introduced one novel D-position into the peptide. For both epitopes complete D-analogs were obtained. The cholera toxin-derived variant dwGsqhydp binds to the antibody TE33 with higher affinity than its original epitope, whereas in the case of the p24-derived analog saGdwwGkssl lower affinity was detected. Both D-peptides are completely stable in serum for several days. Antibody interaction models for both D-molecules were generated by computer-assisted modelling based on the crystal structures of the starting complexes. Compared with the L-peptides, the binding conformation of dwGsqhydp is very similar, whereas saGdwwGkssl displays a completely different interaction mode.
authors.affiliation: Institut für Medizinische Immunologie, Universitätsklinikum Charité, Humboldt-Universität zu Berlin, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kramer
authors.forename: R D
authors.initials: RD
authors.lastname: Stigler
authors.forename: T
authors.initials: T
authors.lastname: Knaute
authors.forename: B
authors.initials: B
authors.lastname: Hoffmann
authors.forename: J
authors.initials: J
authors.lastname: Schneider-Mergener
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology; D000915:Antibody Affinity; D002772:Cholera Toxin / Q000276:immunology*; D003198:Computer Simulation; D003460:Crystallization; D010450:Endopeptidases / Q000378:metabolism; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D016655:HIV Core Protein p24 / Q000276:immunology*; D006207:Half-Life; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry / Q000276:immunology*; D011487:Protein Conformation; D013816:Thermodynamics
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D016655:HIV Core Protein p24; D010455:Peptides; D002772:Cholera Toxin; D010450:Endopeptidases