ABSTRACT
We describe the interaction of a nonepitopic synthetic decapeptide sequence comprising, GQVLQGAIKG, derived from a random sequence with polyclonal IgGs from various animal sources. GQVLQGAIKG was screened for antibody binding activity using ELISA techniques. The peptide showed similar binding characteristics to the IgGs tested. The results were similar whether we used peptide acid or amide. MAP (multiple antigen peptide)-type construct of the peptide was synthesised and employed as an approach to enhance peptide-IgG interaction. The construct, (GQVLQGAIKG)(4)-K(2)-K, showed significant antibody binding activity relative to its monomeric form. These results show that nonepitopic sequences may contribute to binding activity observed in peptide library screening and development of peptide based vaccines. As a cautionary point the measure of antibody binding cannot alone be used to classify peptide as an antigen.
Subject(s)
Antigen-Antibody Reactions , Peptide Library , Vaccines, Synthetic , Enzyme-Linked Immunosorbent Assay , Epitopes , Protein Binding , Sequence Analysis, ProteinABSTRACT
1H-n.m.r. and c.d. studies on sperm-whale myoglobin show that the c.d. signal in the Soret region is inversely and linearly related to the proportion of minor isomer present. An alternative method, 'pH jump', is described for inducing orientational disorder in sperm-whale myoglobin without recourse to reconstitution. 1H-n.m.r. studies on human haemoglobin A indicate little heterogeneity in freshly isolated haemoglobin A, but the effect is enhanced in freeze-dried Sigma haemoglobin A.
Subject(s)
Heme/analysis , Hemoglobin A , Myoglobin , Animals , Circular Dichroism , Humans , Hydrogen-Ion Concentration , Magnetic Resonance Spectroscopy , WhalesABSTRACT
Ligand-binding kinetics of native and reconstituted sperm-whale myoglobin were studied in relation to haem orientational disorder by rapid kinetic methods. In addition, native yellow-fin-tuna myoglobin with significant amount of haem disorder was also used. The O2 dissociation and association rates were found for the proteins with different degrees of haem disorder, and these results suggest that the isomers are characterized by almost identical kinetic parameters. Rates of CO recombination after photolysis were also identical for the two orientational isomers. The results clearly indicate that the rotation of the haem about the alpha-gamma meso axis has little or no effect on the ligand-binding properties of these myoglobins.
Subject(s)
Cetacea/metabolism , Fishes/metabolism , Heme , Myoglobin/metabolism , Tuna/metabolism , Whales/metabolism , Animals , Carbon Monoxide/metabolism , Kinetics , Ligands , Oxygen/metabolism , Photolysis , Protein Binding , Protein Conformation , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Native and reconstituted myoglobin were prepared and their c.d. spectra recorded in the Soret region. Time-dependent changes in dichroism following reconstitution were observed and related to haem orientational disorder. Comparative c.d. studies, in agreement with n.m.r. studies, reveal that the degree and nature of this disorder are species-dependent.