The binding mechanism of a new and possible drug candidate pyrazoline derivative compound K4 and bovine serum albumin (BSA) was investigated in buffer solution (pH 7.4) using ultraviolet-visible light absorption and steady-state and synchronous fluorescence techniques. The fluorescence intensity of BSA was quenched in the presence of K4. The quenching process between BSA and K4 was examined at four different temperatures. Decrease of the quenching constants calculated using the Stern-Volmer equation and at increasing temperature suggested that the interaction BSA-K4 was realized through a static quenching mechanism. Synchronous fluorescence measurements suggested that K4 bounded to BSA at the tryptophan region. Fourier transform infrared spectroscopy results showed that there was no significant change in polarity around the tryptophan residue The forces responsible for the BSA-K4 interaction were examined using thermodynamic parameters. In this study, the calculated negative value of ΔG, the negative value of ΔH and the positive value of ΔS pointed to the interaction being through spontaneous and electrostatic interactions that were dominant for our cases. This study provides a very useful in vitro model to researchers by mimicking in vivo conditions to estimate interactions between a possible drug candidate or a drug and body proteins.

中文翻译：

---

牛血清白蛋白与新型吡唑啉化合物K4之间的结合机制的破译。

利用紫外可见光吸收以及稳态和同步荧光技术研究了一种新的和可能的候选药物吡唑啉衍生物化合物K4与牛血清白蛋白（BSA）在缓冲溶液（pH 7.4）中的结合机理。在K4存在下，BSA的荧光强度被淬灭。在四个不同的温度下检查了BSA和K4之间的淬火过程。使用Stern-Volmer方程计算出的淬灭常数的降低以及在升高的温度下表明，BSA-K4的相互作用是通过静态淬灭机制实现的。同步荧光测量表明，K4在色氨酸区域与BSA结合。傅里叶变换红外光谱结果表明，色氨酸残基周围的极性没有明显变化。使用热力学参数检查了负责BSA-K4相互作用的力。在这项研究中，计算得出的ΔG负值，ΔH负值和ΔS正值表明相互作用是通过自发和静电相互作用进行的，这些相互作用对我们的病例很重要。这项研究通过模仿体内条件来估计可能的候选药物或药物与体内蛋白质之间的相互作用，从而为研究人员提供了非常有用的体外模型。ΔH的负值和ΔS的正值表明相互作用是通过自发和静电相互作用进行的，这些相互作用在我们的病例中占主导地位。这项研究通过模仿体内条件来估计可能的候选药物或药物与体内蛋白质之间的相互作用，从而为研究人员提供了非常有用的体外模型。ΔH的负值和ΔS的正值表明相互作用是通过自发和静电相互作用进行的，这些相互作用在我们的病例中占主导地位。这项研究通过模仿体内条件来估计可能的候选药物或药物与体内蛋白质之间的相互作用，从而为研究人员提供了非常有用的体外模型。