title: A novel strategy for the synthesis of the cysteine-rich protective antigen of the malaria merozoite surface protein (MSP-1). Knowledge-based strategy for disulfide formation.
abstract: The most promising antigen for a protective malaria vaccine is a cysteine-rich domain at the carboxyl terminus of the merozoite surface protein (MSP-1). Passive transfer of anti-MSP-1 antibody or immunization of MSP-1 against infection challenge confers protection in primate and rodent models. The antigen belongs to the three-disulfide epidermal growth factor (EGF) family based on the alignment of the six cysteines. In the K1 strain there are, however, only four cysteines corresponding to the four carboxyl cysteines of EGF. Furthermore, disulfide pairing would produce a non-EGF pattern. Because this cysteine-rich antigen is conformation-dependent, and reduction of the disulfide bonds abolishes antigenicity, we used a synthetic analog to investigate the probable disulfide pairing of this antigen. This paper describes the synthesis, folding and disulfide pairings of two 50-residue cysteine-rich peptides. One contains two disulfides (VK-50) derived from the native sequence of MSP-1 of the Thailand K1 strain (aa 1629-1679). The other contains an EGF-like, three-disulfide [Cys-9,14]VK-50 peptide. Both peptides were synthesized by a solid-phase method using Fmoc-chemistry. The crude peptide of VK-50 was folded, and the disulfide was oxidized by the DMSO method to obtain a structure with an expected disulfide pairing of 3-4, and 5-6. The specific pairing pattern of 1-3, 2-4 and 5-6 in [Cys 9,14]VK-50 corresponding to EGF in [Cys 9,14]VK-50 was obtained using a 'knowledge-based' (KB) strategy for their formation.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: J C
authors.initials: JC
authors.lastname: Spetzler
authors.forename: C
authors.initials: C
authors.lastname: Rao
authors.forename: J P
authors.initials: JP
authors.lastname: Tam
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004220:Disulfides / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000737:chemistry; D017780:Malaria Vaccines / Q000138:chemical synthesis*; D020066:Merozoite Surface Protein 1; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*; D017510:Protein Folding; D011498:Protein Precursors / Q000737:chemistry*; D015800:Protozoan Proteins / Q000737:chemistry*; D013820:Thermolysin / Q000378:metabolism
chemical_list: D004220:Disulfides; D017780:Malaria Vaccines; D020066:Merozoite Surface Protein 1; D010446:Peptide Fragments; D011498:Protein Precursors; D015800:Protozoan Proteins; D004815:Epidermal Growth Factor; D013820:Thermolysin; D003545:Cysteine; D004121:Dimethyl Sulfoxide