Pharmaceutical Biochemistry and Bioanalytics, Pharmaceutical Institute, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany.
Biol Chem. 2022 Aug 31;403(11-12):1055-1066. doi: 10.1515/hsz-2022-0188. Print 2022 Nov 25.
Under hemolytic conditions, hemoglobin and subsequently heme are rapidly released, leading to the toxic effects characterizing diseases such as -thalassemia and sickle cell disease. Herein, we provide evidence that human hemoglobin can bind heme in a transient fashion via surface-exposed sequence motifs. Following the synthesis of potential heme-binding motifs (HBMs) as peptides, their heme-binding capacity was investigated by UV-vis spectroscopy and ranked according to their binding affinity. Heme binding to human hemoglobin was subsequently studied by UV-vis and surface plasmon resonance (SPR) spectroscopy, revealing a heme-binding affinity in the sub- to micromolar range and a stoichiometry that clearly exceeds a 1:1 ratio. molecular docking and simulation studies confirmed heme binding to the respective motifs in the -chain of hemoglobin. Finally, the peroxidase-like activity of hemoglobin and the hemoglobin-heme complex was monitored, which indicated a much higher activity (>1800%) than other heme-peptide/protein complexes reported so far. The present study provides novel insights into the nature of intact hemoglobin concerning its transient interaction with heme, which suggests for the first time potential heme-scavenging properties of the protein at concomitant disassembly and, consequently, a potentiation of hemolysis and related processes.
在溶血性条件下，血红蛋白迅速释放，随后是血红素，导致 - 地中海贫血和镰状细胞病等疾病的特征性毒性作用。本文提供的证据表明，人血红蛋白可以通过表面暴露的序列基序暂时结合血红素。在合成潜在的血红素结合基序 (HBM) 作为肽之后，通过紫外可见光谱法研究了它们的血红素结合能力，并根据结合亲和力对其进行了排名。随后通过紫外可见光谱和表面等离子体共振 (SPR) 光谱研究了人血红蛋白与血红素的结合，发现其血红素结合亲和力在亚毫摩尔至毫摩尔范围内，且计量比明显超过 1:1 。 分子对接和模拟研究证实了血红素与血红蛋白链上的相应基序结合。最后，监测了血红蛋白和血红蛋白-血红素复合物的过氧化物酶样活性，表明其活性比迄今为止报道的其他血红素-肽/蛋白复合物高得多 (>1800%)。本研究为完整血红蛋白与血红素的瞬态相互作用提供了新的见解，这首次表明该蛋白在同时解体时可能具有血红素清除特性，从而增强了溶血和相关过程。
