Effect of Temperature on the Conformation of Extended α-Keratin

Abstract

Attenuated total reflection Fourier transform infrared (ATR/FT-IR) spectra of wet horse hair α-keratin indicate that the conformation of extended α-keratin is affected by the water temperature. Extension of the wet horse hair in 21 °C water gives rise to parallel β-sheet structures, thus suggesting that the original α-helical structure is also parallel. In contrast, extension of the wet horse hair α-keratin in 95 °C water gives rise to anti-parallel β-sheet structures (consistent with reported literature where X-ray diffraction was used), suggesting that disulfide interchange and/or increased chain mobility at elevated temperatures plays a role in altering the secondary structure.

Extracting keratin from wool by using l-cysteine

“…The peaks at low intensity in the 1697-1670 cm −1 range indicate disordered keratin conformations. 14,16 As can be seen in Fig. 6, compared with the natural wool, the regenerated wool shows a decrease of the band area related to the α-helix structure accompanied by an increased β-sheet of the band area.…”

Characterisation of keratin biomass from butchery and wool industry wastes

“…Infrared spectroscopy was extensively used in the molecular conformation study of keratin fibres [22][23][24]; in fact, the Amide I absorption, that originates principally from C@O stretching vibration, is sensitive to the secondary structure of the proteins. Before the acquisition of the spectra, samples were dried at 105°C for 2 h in order to eliminate the water absorption band (1600-1650 cm À1 ) that interferes with the Amide I [25].…”

Study on the structure and properties of wool keratin regenerated from formic acid

“…On the basis of literature data, the absorption at 1650 cm −1 suggests the presence of the ␣-helix structure, whereas the bands related to the ␤-sheet structure fall in the 1631-1515 cm −1 range. The peaks at low intensity in the 1697-1670 cm −1 range indicate disordered keratin conformations [24,30]. Table 2 reports the band assignments for KW and KF samples; the bands not related to the secondary structure are defined as "other".…”