Analyses of the α_DI-domain binding to vitronectin by SPR. Representative profiles of the SPR responses for α_DI-domain binding (concentrations ranging from 0.05 to 3 μM) to vitronectin coupled to the CM5 chip. The “active” α_DI-domain (Pro¹²⁸-Lys³¹⁴) in HBS-P buffer supplemented with 1 mM MgCl₂ was used. RU indicates response units. The inset shows a dose-dependent saturable binding of the α_DI-domain to vitronectin.