[Hemagglutinin of influenza virus type H3: conformation in solution]

The method of circular dichroism was used to evaluate the conformation parameters of the secondary structure of the molecule of isolated influenza virus hemagglutinin H3. Comparison of the data obtained with the similar known parameters for hemagglutinin H2 has shown significant differences in the secondary structure, which are, probably, responsible, (at the level of a higher structural organization) for the variations in the antigenic specificity of hemagglutinins H2 and H3. Temperature and pH stability of alpha-spiral areas of the hemagglutinin H3 molecule was studied, and the direct participation of aromatic amino acid residues in formation of the alpha-spiral areas was shown. The native state of the hemagglutinin alpha-spiral areas may serve as a factor determining potential hemagglutination.