Pressure-Accelerated Dissociation of Amyloid Fibrils in Wild-Type Hen Lysozyme
Pressure-Accelerated Dissociation of Amyloid Fibrils in Wild-Type Hen Lysozyme
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野生型母鸡溶菌酶中淀粉样原纤维的压力加速解离
DOI：
10.1016/j.bpj.2011.10.041
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发表时间：
2012
影响因子：
3.4
通讯作者：
他
中科院分区：
文献类型：
--
作者：
Budda R.Shah;他
淀粉样纤维的动力学，包括它们的形成和解离，在生命中可能是至关重要的。我们使用Trp荧光作为探针研究了在25°C下淀粉样原纤维从野生型鸡溶菌酶在体外解离的动力学，其作为压力的函数。将8 mg ml− 1原纤维溶液在80 mM NaCl（pH 2.2）中稀释100倍后，Trp荧光没有立即发生变化，但在50-450 MPa的压力下，荧光强度随时间迅速下降（kobs= 0.00193 min− 1，0.1 MPa，0.0348 min− 1，400 MPa）。这种现象是由于压力加速了淀粉样纤维分解成单体鸡溶菌酶。根据速率的压力依赖性（在450 MPa时达到平台），我们确定了解离反应的活化体积ΔV0 <$= −32.9 ± 1.7 ml mol（单体）− 1和活化压缩率Δκ <$= −0.0075 ± 0.0006 ml mol（单体）− 1 bar − 1。负的ΔV0 ε和Δκ ε值与来自野生型鸡溶菌酶的淀粉样原纤维处于高体积和高压缩性状态的概念一致，并且解离的过渡状态与原纤维的部分水合作用相结合。
The dynamics of amyloid fibrils, including their formation and dissociation, could be of vital importance in life. We studied the kinetics of dissociation of the amyloid fibrils from wild-type hen lysozyme at 25°C in vitro as a function of pressure using Trp fluorescence as a probe. Upon 100-fold dilution of 8 mg ml−1fibril solution in 80 mM NaCl, pH 2.2, no immediate change occurred in Trp fluorescence, but at pressures of 50–450 MPa the fluorescence intensity decreased rapidly with time (kobs= 0.00193 min−1at 0.1 MPa, 0.0348 min−1at 400 MPa). This phenomenon is attributable to the pressure-accelerated dissociation of amyloid fibrils into monomeric hen lysozyme. From the pressure dependence of the rates, which reaches a plateau at ∼450 MPa, we determined the activation volume ΔV0‡= −32.9 ± 1.7 ml mol(monomer)−1and the activation compressibility Δκ‡= −0.0075 ± 0.0006 ml mol(monomer)−1bar−1for the dissociation reaction. The negative ΔV0‡and Δκ‡values are consistent with the notion that the amyloid fibril from wild-type hen lysozyme is in a high-volume and high-compressibility state, and the transition state for dissociation is coupled with a partial hydration of the fibril.