Secondary structure-improved bioaffinity correlation in elongated and modified synthetic epitope peptides from p24 HIV-1 core protein

Summary In order to study the correlation between secondary structure and bioaffinity of long and modified sequences of p24 protein from HIV-1, three peptides containing the minimal size epitope from region 208–217 (EAAEWDRVHP) were prepared. It was found that peptide p24-1n, an elongated native sequence, has the lowest K_D and a predominant α-helix structure in the presence of trifluoroethanol. Three peptides containing another epitope from region 293–302 (FRDYVDRFK) were also synthesized. We have observed that modifications on the native sequence p24-2n (region 287–308) increased the α-helix content and this was correlated with an improvement of the recognition by antibodies in ELSA. Abbreviations: CD, circular dichroism; DMF, N,N-dimethylformamide; DMSO, dimethyl sulfoxide; ELSA, enzyme linked immunosorbent assay; EDT, 1,2-ethanedithiol; Fmoc, fluorenylmethoxycarbonyl; FAB-MS, fast atom bombardment mass spectrometry; HPLC, high pressure liquid chromatography; MeCN, acetonitrile; NMM, N-methylmorpholine; PyBOP, benzotriazole-1-yl-oxy-tris-pyrrolidino-phosphonium hexafluorophosphate; SELCOM, self consistent method; TMB, 3,3′,5,5′-tetramethylbenzidine; TFA, trifluoroacetic acid; TFE, trifluoroethanol; Aminoacid symbols denote the L-configurations. Abbreviations for amino acids and nomenclature of peptides follow the recommendations of the IUPAC-IUB Commission on Biochemical Nomenclature (Eur. J. Biochem., 138 (1984) 9).