Fig. 1.

VSFG spectra of the water–air interface and an aqueous solution of a 93-μM aqueous AFP-III (pH 7.8) at room temperature. The VSFG spectrum of the water–air interface (black) consists of two broadbands at 3,200 cm⁻¹ and 3,450 cm⁻¹ assigned to hydrogen-bonded liquid water and a sharp peak at 3,700 cm⁻¹ assigned to dangling OH groups sticking out of the surface. The VSFG spectra of AFP-III (red) shows a single strong relatively narrow peak at 3,200 cm⁻¹ and spectral features associated with the CH vibrations of the protein at frequencies <3,000 cm⁻¹. Inset shows the 3D structure of AFP-III (1MSI) with the ice-binding surface highlighted in magenta.