title: Conformational relevance of the beta6Glu replaced by Val mutation in the beta subunits and in the beta(1-55) and beta(1-30) peptides of hemoglobin S.
abstract: The beta subunits of hemoglobin S showed a higher ellipticity than the beta subunits of the hemoglobin A, both in the Soret and near-ultraviolet regions. The apoderivatives of the beta subunits of hemoglobin S showed a lower helical content and a larger amount of beta conformation than the apoderivatives of the beta subunits of hemoglobin A. The beta(1-55) peptides and beta(1-30) peptides from the beta subunits of hemoglobin A and S have been separated and analyzed. The betaS(1-55) peptide showed a higher content of beta conformation and lower amount of alpha helix when compared to the betaA(1-55) peptide. This difference was present also in different concentrations of methanol. The apoderivative from the beta subunits of hemoglobin S and the betaS(1-55) peptide aggregated with increasing ionic strength. The CD measurement showed that their secondary structure did not change upon a 10-fold dilution of the sample. Very little secondary structure was present in the betaS(1-30) peptide, and the CD spectrum was very similar to that of the betaA(1-30) peptide. No significant difference in aggregation was found between the betaS(1-30) and betaA(1-30) peptides.
mesh_terms: D000595:Amino Acid Sequence; D001059:Apoproteins; D001665:Binding Sites; D002942:Circular Dichroism; D014644:Genetic Variation; D005971:Glutamates; D006451:Hemoglobin, Sickle; D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D006801:Humans; D008970:Molecular Weight; D010446:Peptide Fragments; D011485:Protein Binding; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D014633:Valine
chemical_list: D001059:Apoproteins; D005971:Glutamates; D006451:Hemoglobin, Sickle; D006454:Hemoglobins; D006455:Hemoglobins, Abnormal; D010446:Peptide Fragments; D014633:Valine