SPR-detected interaction between the (β15–66)2
and VLDLR(1–8) fragments at different concentrations of NaCl, 0.15 M (A),
0.2 M (B), 0.25 (C), and 0.3 M (D). The (β15–66)2
fragment at increasing concentrations, 0.25, 0.5, 1, 2.5 and 5 nM (A), 0.5, 1,
2.5, 5 and 10 nM (B), and 1, 2.5, 5, 10, and 25 (C and D), was added to the
immobilized VLDLR(1–8) fragment and its association/dissociation was
monitored in real time while registering the resonance signal (response) using
BIAcore biosensor. The dotted curves represent the best fit of the binding data
using global fitting analysis (see Materials and
Methods); the determined Kd values are
presented in Table 2. (E) Debye-Huckel
plots for binding of VLDLR(1–8) to (β15–66)2 at
different ionic strengths. The Kd values were taken
from SPR data presented in panels A-D and Table
2, and the log10Kd values
represent an average of at least three independent experiments ± SD; a
slope of 5.2 ± 0.2 was determined by linear regression analysis.