The Environmental Science & Engineering Program, The University of Texas at El Paso, El Paso, TX 79968, USA.
The Department of Chemistry & Biochemistry, The University of Texas at El Paso, El Paso, TX 79968, USA.
Int J Biol Macromol. 2024 Apr;264(Pt 1):130416. doi: 10.1016/j.ijbiomac.2024.130416. Epub 2024 Feb 28.
Carbon nanomaterials (CNMs), including carbon quantum dots (CQDs), have found widespread use in biomedical research due to their low toxicity, chemical tunability, and tailored applications. Yet, there exists a gap in our understanding of the molecular interactions between biomacromolecules and these novel carbon-centered platforms. Using gelatin-derived CQDs as a model CNM, we have examined the impact of this exemplar nanomaterial on apo-myoglobin (apo-Mb), an oxygen-storage protein. Intrinsic fluorescence measurements revealed that the CQDs induced conformational changes in the tertiary structure of native, partially unfolded, and unfolded states of apo-Mb. Titration with CQDs also resulted in significant changes in the secondary structural elements in both native (holo) and apo-Mb, as evidenced by the circular dichroism (CD) analyses. These changes suggested a transition from isolated helices to coiled-coils during the loss of the helical structure of the apo-protein. Infra-red spectroscopic data further underscored the interactions between the CQDs and the amide backbone of apo-myoglobin. Importantly, the CQDs-driven structural perturbations resulted in compromised heme binding to apo-myoglobin and, therefore, potentially can attenuate oxygen storage and diffusion. However, a cytotoxicity assay demonstrated the continued viability of neuroblastoma cells exposed to these carbon nanomaterials. These results, for the first time, provide a molecular roadmap of the interplay between carbon-based nanomaterial frameworks and biomacromolecules.
碳纳米材料（CNMs），包括碳量子点（CQDs），由于其低毒性、化学可调性和针对性应用，在生物医学研究中得到了广泛的应用。然而，我们对生物大分子与这些新型碳基平台之间的分子相互作用的理解还存在差距。本研究以明胶衍生的 CQDs 为模型 CNM，考察了这种典型纳米材料对去氧肌红蛋白（apo-Mb）这种储氧蛋白的影响。内源荧光测量表明，CQDs 诱导了 apo-Mb 的天然、部分展开和展开状态的三级结构构象变化。用 CQDs 滴定也导致了天然（全）和 apo-Mb 中二级结构元件的显著变化，这一点可以通过圆二色性（CD）分析得到证明。这些变化表明，在 apo 蛋白螺旋结构丧失的过程中，从孤立的螺旋过渡到卷曲螺旋。红外光谱数据进一步强调了 CQDs 与 apo-myoglobin 的酰胺骨架之间的相互作用。重要的是，CQDs 驱动的结构扰动导致血红素与 apo-myoglobin 的结合受损，因此可能会降低氧的储存和扩散能力。然而，细胞毒性试验表明，接触这些碳纳米材料的神经母细胞瘤细胞仍然具有活力。这些结果首次提供了碳基纳米材料框架与生物大分子相互作用的分子路线图。
