title: Evidence for the alpha-helicity of class II MHC molecular binding sites for the superantigen, staphylococcal enterotoxin A.
abstract: Circular dichroism (CD) spectra of class II MHC peptides revealed the alpha-helical conformation of superantigen-binding peptides I-A beta b(60-90), I-A beta b(65-85), and I-A alpha b(51-80), but not the nonbinding peptide I-A beta b(80-100). These CD spectra provide biophysical evidence for the alpha-helicity of class II MHC molecular binding sites for the superantigen, staphylococcal enterotoxin A (SEA). Alanine-substituted analogs of the SEA binding-site peptide, I-A beta b(65-85), were used to implicate beta-chain residues 72 and 80 in class II MHC-SEA binding. The data support SEA binding away from the class II antigen binding cleft along the faces of the alpha-helices.
authors.affiliation: Department of Microbiology and Cell Science, University of Florida, Gainesville 32611.
authors.forename: J K
authors.initials: JK
authors.lastname: Russell
authors.forename: M A
authors.initials: MA
authors.lastname: Jarpe
authors.forename: H M
authors.initials: HM
authors.lastname: Johnson
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D001710:Biotin; D002942:Circular Dichroism; D004768:Enterotoxins / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D000949:Histocompatibility Antigens Class II / Q000737:chemistry* / Q000276:immunology; D008961:Models, Structural; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013211:Staphylococcus aureus
chemical_list: D004768:Enterotoxins; D000949:Histocompatibility Antigens Class II; D010455:Peptides; C026066:enterotoxin A, Staphylococcal; D001710:Biotin