Conformations of peptide fragments comprising the complete sequence of component III of Chi t I and their relationship to T-cell stimulation.
Conformational preferences of synthetic peptides that span the complete sequence of Chironomus thummi hemoglobin (Chi t I) component III were studied by nuclear magnetic resonance (NMR) and CD spectroscopies. The peptides, 19-21 amino acids in length, were studied in water, except for the C-terminal peptide, which was investigated in DMSO-d6. NMR showed that all investigated peptides lacked uniquely folded conformations in water at 4 degrees C and pH 3.0 or at 10 degrees C and pD 6.6 in DMSO. However, some preferential helix-like conformations for the peptides corresponding to the helices of the folded protein could be seen in solution. These peptides showed characteristic interactions for conformations in both the beta- and alpha-regions of phi-psi space, based on strong C alpha H(i)-NH(i + 1) interactions, and on NH-NH, C alpha H(i)-NH-(i + 2), C alpha H(i)-NH(i + 3), and C alpha H(i)-C beta H(i + 3) interactions, respectively. Helical motifs seem not to be the most important factors in determining MHC-binding and/or T-cell recognition. However, there is a tendency that more stabilized secondary structures show higher T-cell stimulation.
Czisch
M
M
Max-Planck-Institut für Biochemie, Martinsried bei München, FRG.
Liebers
V
V
Bernstein
R
R
Chen
Z
Z
Baur
X
X
Holak
T A
TA
D000485:Allergens / Q000737:chemistry* / Q000276:immunology; D000595:Amino Acid Sequence; D000818:Animals; D002683:Chironomidae / Q000737:chemistry* / Q000276:immunology; D002942:Circular Dichroism; D006454:Hemoglobins / Q000737:chemistry* / Q000276:immunology; D019476:Insect Proteins; D008213:Lymphocyte Activation; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000276:immunology; D017433:Protein Structure, Secondary; D012995:Solubility; D013329:Structure-Activity Relationship; D013601:T-Lymphocytes / Q000502:physiology*
D000485:Allergens; C071697:Chi t I allergen; D006454:Hemoglobins; D019476:Insect Proteins; D010446:Peptide Fragments