Cooperative unfolding of α-keratin



The unfolding of the α-helices of the microfibrils in α-keratin fibers such as wool proceeds in a cooperative manner. When a wool fiber is extended in water, the load-extension curve obtained indicates on the basis of relationships derived from rate process theory, that the number of α-helical residues n that unfold simultaneously is at least 50. This is probably an underestimation, as fiber diameter variability severely reduced any estimate of the value of n. Other experimental evidence is also indicated that support the existence of considerable mechanical cooperation between α-helical components.