Conformation and topology of amyloid beta-protein adsorbed on a tethered artificial membrane probed by surface plasmon field-enhanced fluorescence spectroscopy.
Progressive depositions of cerebral amyloid are primary neuropathologic features of Alzheimer's disease (AD). The amyloid is composed of a 39-42 amino acid peptide called the amyloid beta-protein (Abeta). Repeated investigation suggests that the conformational transition of Abeta from alpha-helix or random coil to beta-sheet structure plays a key role in the inappropriate accumulation of cerebral amyloid plaques. In this manuscript, we describe a fluorescence-based immunoassay technology to investigate the conformation and topology of Abeta peptides interacting with peptide-tethered planar lipid bilayers. Dual monoclonal antibodies (mAbs) labelled with fluorophores were employed to recognise a linear N- and a beta-sheet C-terminus of Abeta peptides on the model membrane, respectively. Kinetics of antibody-Abeta binding were determined by surface plasmon field-enhanced fluorescence spectroscopy (SPFS). The conformational transition of Abeta by melatonin, a defined beta-sheet breaker, was probed using paired monoclonal antibodies. The Abeta interaction with the membrane was evaluated by carefully analyzing the change in kinetic/affinity parameters in the presence or absence of melatonin. These results show that SPFS can be used to examine conformational transition of Abeta on an artificial membrane, providing a novel and versatile platform for conveniently monitoring protein-membrane interaction and screening for new beta-sheet breakers.
Song
Haipeng
H
Max Planck Institute for Polymer Research, Mainz, Germany.
Ritz
Sandra
S
Knoll
Wolfgang
W
Sinner
Eva-Kathrin
EK
D000042:Absorption; D016229:Amyloid beta-Peptides / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry; D008567:Membranes, Artificial; D008954:Models, Biological; D013050:Spectrometry, Fluorescence; D020349:Surface Plasmon Resonance
D016229:Amyloid beta-Peptides; D008051:Lipid Bilayers; D008567:Membranes, Artificial