Ultrasonic spectroscopy in bovine serum albumin solutions.
Ultrasonic spectroscopy in bovine serum albumin solutions.
复制标题
牛血清白蛋白溶液中的超声波光谱。
DOI：
10.1121/1.2025804
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
K. Takagi
中科院分区：
文献类型：
--
作者：
P. Choi;J. Bae;K. Takagi
在20 ℃、0.1-1600 MHz、pH 1.5-13.2的宽频率范围内测量了牛血清白蛋白（BSA）水溶液的超声吸收和速度谱。使用了五种不同的技术：平凹谐振腔、平平谐振腔、脉冲回波重叠、布拉格反射和高分辨率布拉格反射方法。中性pH下的吸收光谱与弛豫曲线拟合良好，假设弛豫频率分布具有高频截止和长低频尾部。根据BSA分子的不同水合程度解释了松弛行为。在酸性pH下，超过pH 7的过量吸收由双弛豫解释。弛豫频率和单波长最大吸收的pH依赖性表明，在200 kHz附近的弛豫与分子的膨胀有关，而在2 MHz附近的弛豫则是由羧基的质子转移反应引起的.在碱性pH下，过量吸收由三重弛豫解释。在约200 kHz的弛豫与螺旋线圈过渡，在2和15 MHz的两个弛豫归因于酚和氨基的质子转移反应，分别。与这些过程相关的速率常数和体积变化进行了估计。
Ultrasonic absorption and velocity spectra in bovine serum albumin (BSA) aqueous solutions have been measured at 20 degrees C over the broad frequency range 0.1-1600 MHz in the pH range 1.5-13.2. Five different techniques were used: the plano-concave resonator, plano-plano resonator, pulse-echo overlap, Bragg reflection, and high-resolution Bragg reflection methods. The absorption spectrum at neutral pH was well fitted to the relaxation curve assuming a distribution of relaxation frequency with a high-frequency cutoff and long low-frequency tail. The relaxation behavior was interpreted in terms of various degrees of hydration of BSA molecules. At acid pH's, excess absorption over that at pH 7 was explained by double relaxation. The pH dependences of the relaxation frequency and maximum absorption per wavelength showed that the relaxation at about 200 kHz was related to the expansion of molecules and that at 2 MHz resulted from the proton transfer reaction of carboxyl group. At alkaline pH's, the excess absorption was explained by triple relaxation. The relaxation at about 200 kHz was associated with a helix-coil transition, and the two relaxations at 2 and 15 MHz were attributed to the proton transfer reactions of phenolic and amino groups, respectively. The rate constants and volume changes associated with these processes were estimated.