Keratin homogeneity in the tail feathers of Pavo cristatus and Pavo cristatus mut. alba.
Bottom Line: In the final structure, the crystalline beta-cores are fixed by the rest of the keratin molecule.The hydrophobic residues of the beta-core are locked into a zip-like arrangement.Structurally there is no difference between the blue and the white bird.
Affiliation: University of Vienna, Faculty of Physics, Strudlhofgasse 4, A-1090 Vienna, Austria.Show MeSH
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Mentions: For the structural development we propose therefore the model of Fig. 9: during growth, the pairs of β-sheets forming the filament are already present, but their initial orientation with respect to the helix is not well fixed over the first 50 mm from the calamus. Beyond they fall into a highly aligned and oriented structure. The half-widths of both the axial and lateral reflections decrease. The strong increase in alignment is accompanied by only a small shortening of the axial repeat unit, and no change of the intersheet distance. This leads to the conclusion that topologically the crystalline beta structure of the strands is formed early on. Only some small rotations are needed to fix the structure in a zip-like mechanism, where the sidechains perfectly interleave along the filament axis (Fraser and Parry, 2008). The high concentration of hydrophobic residues between the two strands and their interaction is important for the assembly process. They stabilize the final structure (Fraser and Parry, 2008).
Affiliation: University of Vienna, Faculty of Physics, Strudlhofgasse 4, A-1090 Vienna, Austria.