Secondary Structure of the Homologous Proteins, A A-Fetoprotein and Serum Albumin, from their Circular Dichroism and Infrared Spectra

Secondary structure composition of two homologous proteins, alpha-fetoprotein and serum albumin, has been compared using circular dichroism and Fourier-transform infrared spectroscopy. CD-only analysis gives an accurate a-helical content for SA, but underestimates the predicted value for AFP. In contrast, FTIR-only analysis underestimates the helical content of SA. However, analysis of hybrid IR-CD spectra gives more accurate values for secondary structure composition for both AFP and SA and shows that the secondary structures of these proteins are the same.