School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.
School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.
J Inorg Biochem. 2023 Sep;246:112296. doi: 10.1016/j.jinorgbio.2023.112296. Epub 2023 Jun 17.
The sequence and structure of human cytochrome c (hCyt c) exhibit evolutionary conservations, with only a limited number of naturally occurring mutations in humans. Herein, we investigated the effects of the naturally occurring S47F/A mutations on the structure and function of hCyt c in the oxidized form. Although the naturally occurring S47F/A mutations did not largely alter the protein structure, the S47F and S47A variants exhibited a small fraction of high-spin species. Kinetic studies showed that the peroxidase activity of the variants was enhanced by ∼2.5-fold under neutral pH conditions, as well as for the rate in reaction with HO, when compared to those of wild-type hCyt c. In addition, we evaluated the interaction between hCyt c and human neuroglobin (hNgb) by isothermal titration calorimetry (ITC) studies, which revealed that the binding constant was reduced by ∼8-fold as result of the mutation of the hydrophilic Ser to the hydrophobic Phe/Ala. These findings provide valuable insights into the role of Ser47 in Ω-loop C in sustaining the structure and function of hCyt c.
人细胞色素 c（hCyt c）的序列和结构具有进化保守性，在人类中只有有限数量的天然发生的突变。在此，我们研究了天然发生的 S47F/A 突变对氧化形式的 hCyt c 结构和功能的影响。尽管天然发生的 S47F/A 突变没有很大地改变蛋白质结构，但 S47F 和 S47A 变体表现出少量的高自旋物种。动力学研究表明，与野生型 hCyt c 相比，变体在中性 pH 条件下的过氧化物酶活性增强了约 2.5 倍，与 HO 的反应速率也增强了。此外，我们通过等温滴定量热法（ITC）研究评估了 hCyt c 与人类神经球蛋白（hNgb）之间的相互作用，结果表明，由于亲水丝氨酸突变为疏水性苯丙氨酸/丙氨酸，结合常数降低了约 8 倍。这些发现为 Ser47 在维持 hCyt c 结构和功能的 Ω 环 C 中的作用提供了有价值的见解。
