FT-IR study of the Ca2+-binding to bovine α-lactalbumin Relationships between the type of coordination and characteristics of the bands due to the Asp COO− groups in the Ca2+-binding site

AbstractFourier-transform infrared spectroscopy (FT-IR) was applied to examine relationships between the type of coordination and the COO− antisymmetric and symmetric stretches of the COO− groups in the Ca2+-binding site of bovine α-lactalbumin. The peaks at 1593, 1578, 1425, and 1403 cm−1 were assigned to the COO− groups of Asp-82, 87, and 88 coordinating to Ca2+ in the pseudo bridging mode, according to the results of X-ray crystallography. The bands due to the COO− groups were quite similar to each other between α-lactalbumin and EDTA which is the model compound for the pseudo bridging state