Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
Poznan University of Life Sciences, Department of Animal Nutrition, Poznan, Poland; Biopolymers, Interactions, Assemblies, UR 1268, Institute National de la Recherche Agronomique, Nantes, France.
Spectrochim Acta A Mol Biomol Spectrosc. 2019 Jun 15;217:155-163. doi: 10.1016/j.saa.2019.03.077. Epub 2019 Mar 25.
Polymyxin B and E (colistin), are a group of cationic charged cyclic antibiotic lipopeptides that are frequently used in the clinics to treat infections caused by the multidrug-resistant gram-negative bacteria. Since the interactions with the blood plasma drug-transport proteins may play a critical role in determining their pharmacological and pharmacokinetic profiles, we studied the binding properties of polymyxins to the human serum albumin (HSA) under simulated physiological conditions by the combination of biophysical approaches, such as isothermal titration calorimetry (ITC), fluorescence anisotropy, circular dichroism (CD) buttressed by computational studies. The HSA binding to the polymyxins was relatively strong (K ≈ 1.0 × 10 M). Molecular docking indicated that polymyxins bind to the cleft of HSA between domains I and III via the electrostatic interactions. This evidence was further confirmed by the entropy-driven interaction for the polymyxins bound HSA. Far UV-CD experiments showed that the secondary structure of HSA doesn't alter and its stable structure is preserved. Collectively, these investigations revealed that the polymyxins bind preferentially to the partially unfolded intermediate forms of the protein structure; however, HSA molecule does not undergo any significant conformational changes upon binding. This is promising as it may limit the unfavorable side effects of the medicine. On the whole, the results provide quantitative and qualitative insight of the binding interaction between HSA and polymyxins, which is important in understanding their effect as therapeutic agents.
黏菌素 B 和 E（多黏菌素）是一组带正电荷的环状抗生素脂肽，常用于临床治疗多重耐药革兰氏阴性菌引起的感染。由于与血浆药物转运蛋白的相互作用可能在决定其药理和药代动力学特征方面发挥关键作用，因此我们在模拟生理条件下，通过等温滴定量热法（ITC）、荧光各向异性、圆二色性（CD）等生物物理方法与计算研究相结合，研究了黏菌素与人类血清白蛋白（HSA）的结合特性。HSA 与黏菌素的结合相对较强（K≈1.0×10M）。分子对接表明，黏菌素通过静电相互作用结合到 HSA 结构域 I 和 III 之间的裂隙中。这一证据进一步得到了与 HSA 结合的黏菌素的熵驱动相互作用的证实。远紫外 CD 实验表明，HSA 的二级结构没有改变，其稳定结构得以保留。总之，这些研究表明，黏菌素优先与蛋白质结构的部分展开中间态结合；然而，HSA 分子在结合时不会发生任何显著的构象变化。这是有希望的，因为它可能限制药物的不利副作用。总的来说，这些结果提供了 HSA 与黏菌素之间结合相互作用的定量和定性见解，这对于理解它们作为治疗剂的作用很重要。
