Binding of ¹²⁵I-defensin to Lp(a) assessed by gel filtration. Fixed amounts Lp(a) or BSA (10 nmol/L each) were incubated with the indicated concentrations of¹²⁵I-defensin (HNP-1) for 1 hour at 37°C. The mixtures were loaded on a Bio-spin 30 columns, and the excluded radioactivity was measured. The amount of ¹²⁵I-defensin/PBS and the amount of ¹²⁵I-defensin/BSA in the void volume were identical at each concentration and were taken as measure of nonspecific binding. The insert shows the void volume of columns containing ¹²⁵I-defensin plus Lp(a), BSA, and buffer.