1Department of Pharmaceutical Chemistry, College of Pharmacy, Jazan University, PO Box 114, Jazan, Saudi Arabia; 2Substance Abuse and Toxicology Research Center, Jazan University, PO Box 114, Jazan, Saudi Arabia.
Department of Pharmaceutical Chemistry, College of Pharmacy, Jazan University, PO Box 114, Jazan, Saudi Arabia.
Acta Biochim Pol. 2021 Feb 17;68(1):99-107. doi: 10.18388/abp.2020_5462.
Serum albumin protein plays a key role in the transportation and distribution of bioactive species including metal ions and metal-based drugs and, therefore, the nature of their binding could provide important insight for the development of new drugs. In the present investigation, binding interactions of bovine serum albumin (BSA) with three biologically important metal ions: Pt4+, Ir3+ and Fe2+ were screened using easy-to-use and cost-effective Fourier-Transform Infrared (FT-IR) and Ultraviolet-Visible (UV-Vis) spectroscopic techniques. Prior to the screening, the protein and metal ions were allowed to interact at physiological pH (7.4) and the spectral changes were monitored upon interaction. In FT-IR spectrum, the position of amide I band (C=O stretching) was shifted from 1652 cm-1 in case of free BSA to 1659, 1657 and 1656 cm-1 in BSA-Pt4+, BSA-Ir3+ and BSA-Fe2+ complexes, respectively. This spectral shifting was due to the binding of metal ions to N and O atoms of BSA peptide bonds. The interaction was further demonstrated by a remarkable reduction in spectral intensities of amide I and II bands. Secondary protein structure analysis revealed conformational changes characterized by a substantial decrease in α-helix (11.29-27.41%) accompanied by an increase in β-sheet and β-antiparallel contents. The absorption of BSA at a constant concentration at 280 nm was successively reduced as the concentration of Pt4+ and Ir3+ ions increased. On the other hand, the absorption of BSA-Fe2+ complex successively increased with the increase in the concentration of Fe2+ in the test solution. The binding constants for BSA-Pt4+, BSA-Ir3+ and BSA-Fe2+ complexes were calculated to be 1.55×104, 5.67×104 and 3.78×104 M-1, respectively. The results revealed that the three metal ions showed binding affinities with the BSA protein in the order: Ir3+>Fe2+>Pt4+.
血清白蛋白在生物活性物质（包括金属离子和金属基药物）的运输和分布中起着关键作用，因此，它们的结合性质可以为新药物的开发提供重要的见解。在本研究中，使用易于使用且具有成本效益的傅里叶变换红外（FT-IR）和紫外可见（UV-Vis）光谱技术筛选了三种生物重要金属离子（Pt4+、Ir3+和 Fe2+）与牛血清白蛋白（BSA）的结合相互作用。在筛选之前，允许蛋白质和金属离子在生理 pH（7.4）下相互作用，并在相互作用时监测光谱变化。在 FT-IR 光谱中，酰胺 I 带（C=O 伸缩）的位置从游离 BSA 的 1652cm-1 移至 BSA-Pt4+、BSA-Ir3+和 BSA-Fe2+ 络合物中的 1659、1657 和 1656cm-1。这种光谱移动是由于金属离子与 BSA 肽键的 N 和 O 原子结合所致。这种相互作用进一步通过酰胺 I 和 II 带的光谱强度显著降低得到证明。二级蛋白质结构分析表明构象发生变化，特征是α-螺旋（11.29-27.41%）大量减少，同时β-折叠和β-反平行含量增加。在 280nm 处固定浓度的 BSA 的吸收随着 Pt4+和 Ir3+离子浓度的增加而依次降低。另一方面，随着测试溶液中 Fe2+浓度的增加，BSA-Fe2+络合物的吸收依次增加。BSA-Pt4+、BSA-Ir3+和 BSA-Fe2+络合物的结合常数分别计算为 1.55×104、5.67×104 和 3.78×104M-1。结果表明，三种金属离子与 BSA 蛋白的结合亲和力顺序为：Ir3+>Fe2+>Pt4+。
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