基于小波熵的白蛋白热变性动态散斑研究

Investigation of Thermal Denaturation of Albumin Using Dynamic Speckle Based on Wavelet Entropy

利用基于小波熵的动态散斑方法研究了白蛋白的热变性过程。采用CCD相机得到了白蛋白热变性过程中的动态散斑图序列;用动态散斑图序列生成了时序散斑图(THSP),再以小波熵为参数,将THSP的每一行分为8个时间窗口,利用db4正交小波对每个窗口进行了三级小波分解,得到了256×256×8的三维小波熵值矩阵。对小波熵值矩阵图像化为8幅256×256的灰度图,直观分析了动态散斑信号的变化规律,进而分析了白蛋白热变性过程中蛋白质分子系综的运动特性。结果表明,利用基于小波熵的动态散斑方法,能对白蛋白热变性过程中蛋白质分子的运动及凝聚过程进行初步的定量分析和研究。该方法是研究溶液中微粒运动的有力手段。

The process of thermal denaturation of the albumin was studied using dynamic speckle method based on wavelet entropy. At first, the dynamic speckle pattern sequences generated by albumin colloid during denaturing were acquired using charge-compled device （CCD） camera. Using the speckle sequences, the time history of speckle patterns （THSP） were generated. And then, with the wavelet entropy as a parameter, each row of THSP was separated into eight time windows which were decomposed by db4 orthogonal wavelet family into three levels. Thus a three-dimensional matrix of 256 × 256 × 8 of wavelet entropy was generated. Finally, this matrix was grayed into eight 256× 256 patterns, which made the change of dynamic speckle signals visulized. According to the patterns, the movement properties of the protein molecule ensemble were analyzed during thermal denaturation of the albumin. The results show that this method is effective to analyze the process of movement and aggregation of protein molecules quantitatively. Experimental results prove that this method is a useful tool to investigate the motion of particles in solution.