Pressure-jump NMR study of dissociation and association of amyloid protofibrils.
The dissociation and reassociation processes of amyloid protofibrils initiated by pressure-jump have been monitored with real-time (1)H NMR spectroscopy using an intrinsically denatured disulfide-deficient variant of hen lysozyme. Upon pressure-jump up to 2 kbar, the matured protofibrils grown over several months become fully dissociated into monomers within a few days. Upon pressure-jump down to 30 bar, the dissociated monomers immediately start reassociating. The association and dissociation cycle can be repeated reproducibly by alternating pressure, establishing a notion that the protofibril formation is simply a slow kinetic process toward thermodynamic equilibrium. The outstanding simplicity and effectiveness of pressure in controlling the protofibril formation opens a new route for investigating mechanisms of amyloid fibril-forming reactions. The noted variation in the pressure-induced dissociation rate with the progress of the association reaction suggests multiple mechanisms for the elongation of the protofibril. The disulfide-deficient hen lysozyme offers a particularly simple model system for thermodynamic and kinetic studies of protofibril formation as well as for screening drugs for amyloidosis.
Kamatari
Yuji O
YO
Structural and Molecular Biology Laboratory, RIKEN Harima Institute/Spring-8, Mikazuki-cho, Sayo-gun, Hyogo 679-5148, Japan.
Yokoyama
Shigeyuki
S
Tachibana
Hideki
H
Akasaka
Kazuyuki
K
D000682:Amyloid / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D002645:Chickens; D018625:Microscopy, Atomic Force; D009113:Muramidase / Q000502:physiology* / Q000648:ultrastructure; D019906:Nuclear Magnetic Resonance, Biomolecular; D011312:Pressure; D011489:Protein Denaturation; D013816:Thermodynamics
D000682:Amyloid; D009113:Muramidase