不同温度的牛血清白蛋白的太赫兹光谱研究

利用太赫兹时域光谱技术，测量了加热到298，308，328和348 K的牛血清白蛋白(BSA)固体样本的低频光谱，测量过程中获得了BSA样本的折射系数曲线、吸收系数曲线。由于BSA样本的THz折射系数和吸收系数光谱曲线存在重叠现象，采用主成分分析法对BSA样本的折射系数、吸收系数、复介电系数虚部及介电损耗角正切，共四个太赫兹光谱参数进行分析，发现样本未变性前，介电损耗角的正切与牛血清白蛋白样本的温度最相关，相关系数达到99.76%。采用模糊聚类方法区分变性前后的BSA固体样本，建立不同温度的BSA模糊识别模型，发现可以将未变性的样本与已经变性的样本区分开，为检测不同温度蛋白质特性的太赫兹光谱法提供新的途径。

Investigation of Bovine Serum Albumin at Different Temperatures by Terahertz Time-Domain Spectroscopy

As the temperature changes, the stability of bovine serum albumin (BSA) molecules’ interior structure may change. We measured the low frequency spectra of BSA’s solid sample heated to 298, 308, 328 and 348 K based on the technology of Terahertz Time-Domain Spectroscopy. According to refractive index curve and absorption coefficient curve, the refractive index of samples at different temperatures changes obviously, showing that the interior structure of samples changes; as temperature goes up, samples’ absorptive capacity has an obvious increase, but the sample at 348 K has a sudden decrease in absorption coefficient on average, showing that the samples have a denaturation. At the main time, using the theory of THz-TDS, we can get the relation that BSA’s imaginary part of dielectric coefficient and dielectric loss tangent change with frequency. Using Principal Component Analysis to reduce dimensionality, when the first three principal components reach to 98.69% of the amount of information of original data, we found that compared to refractive index, absorption coefficient, imaginary part of dielectric coefficient, dielectric loss tangent is most relevant to the temperature of the samples of BSA, with correlation coefficient reaching 99.76%. Combine PCA and fuzzy recognition, build BSA’s recognition models, and we gain a method to judge BSA’s temperature.