The keratin structure in the cortex of peacocks' feathers is studied by X-ray diffraction along the feather, from the calamus to the tip. It changes considerably over the first 5. cm close to the calamus and remains constant for about 1. m along the length of the feather. Close to the tip, the structure loses its high degree of order. We attribute the X-ray patterns to a shrinkage of a cylindrical arrangement of β-sheets, which is not fully formed initially. 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. © 2010 Elsevier Inc.
Pabisch, S., Puchegger, S., Kirchner, H. O. K., Weiss, I. M., & Peterlik, H. (2010). Keratin homogeneity in the tail feathers of Pavo cristatus and Pavo cristatus mut. alba. Journal of Structural Biology, 172(3), 270–275. https://doi.org/10.1016/j.jsb.2010.07.003