Human S100A5 binds Ca2+ and Cu2+ independently

摘要

BackgroundS100A5 is a calcium binding protein found in a small subset of amniote tissues. Little is known about the biological roles of S100A5, but it may be involved in inflammation and olfactory signaling. Previous work indicated that S100A5 displays antagonism between binding of Ca²⁺ and Cu²⁺ ions—one of the most commonly cited features of the protein. We set out to characterize the interplay between Ca²⁺ and Cu²⁺ binding by S100A5 using isothermal titration calorimetry (ITC), circular dichroism spectroscopy (CD), and analytical ultracentrifugation (AUC).