Helix III is less rigid , makes an average angle of about 90 degrees with helices I and II , and constitutes the other arm of the molecule .
helix iii is less rigid , makes an average angle of about 90 degrees with helices i and ii , and constitutes the other arm of the molecule .
B-protein_substructure I-protein_substructure O O O O O O O O O O O O O O O O O O O O O O O O O O O