Kamatari Yuji O, Yokoyama Shigeyuki, Tachibana Hideki, Akasaka Kazuyuki
Structural and Molecular Biology Laboratory, RIKEN Harima Institute/Spring-8, Mikazuki-cho, Sayo-gun, Hyogo 679-5148, Japan.
J Mol Biol. 2005 Jun 24;349(5):916-21. doi: 10.1016/j.jmb.2005.04.010.
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.
利用鸡溶菌酶的一种内在变性的、缺乏二硫键的变体，通过实时¹H NMR光谱监测了压力跳跃引发的淀粉样原纤维的解离和重新缔合过程。压力跃升至2 kbar时，经过数月生长的成熟原纤维在几天内完全解离成单体。压力跃降至30 bar时，解离的单体立即开始重新缔合。通过交替施加压力，可以重复进行缔合和解离循环，这确立了一个观点，即原纤维的形成仅仅是朝着热力学平衡的一个缓慢动力学过程。压力在控制原纤维形成方面的显著简单性和有效性为研究淀粉样纤维形成反应的机制开辟了一条新途径。随着缔合反应的进行，压力诱导的解离速率出现明显变化，这表明原纤维伸长存在多种机制。缺乏二硫键的鸡溶菌酶为原纤维形成的热力学和动力学研究以及筛选淀粉样变性药物提供了一个特别简单的模型系统。
