Interaction between human amphipathic apolipoproteins and amyloid β-peptide: surface plasmon resonance studies

Abstract

Several apolipoproteins including apoE and apoA-I are known to be associated with amyloid β-peptide, a major component of senile plaques in Alzheimer's disease. In the present study the interaction between three human amphipathic apolipoproteins apoE3, apoA-I and apoA-II and immobilized amyloid β-peptide (1–40) was quantified by plasmon resonance. The interactions were saturable and reversible. The results demonstrated a high affinity of the binding of amphipathic apolipoproteins to amyloid β-peptide. On the other hand, only a small population of synthetic amyloid β-peptide participated in the interaction. The apparent equilibrium dissociation constants K D were 10 nM for apoE3, 25 nM for apoA-I and 80 nM for apoA-II under physiological conditions. The affinity of the apoE3-amyloid β-peptide binding was not affected by pH in the range 6.0–8.0 but was significantly increased by high salt concentration. ApoA-I mainly followed similar patterns. A major participation of hydrophobic forces in the binding of apoE3 and apoA-I to amyloid β-peptide was suggested.