BACKGROUND & MOTIVATION Peptides and proteins can interact with heme through His, Tyr, or Cys in heme-regulatory motifs (HRMs). The Cys-Pro dipeptide is a well investigated HRM, but for His and Tyr such a distinct motif is currently unknown. In addition, many heme-peptide complexes, such as heme-amyloid β, can display a peroxidase-like activity, albeit there is little understanding of how the local primary and secondary coordination environment influences catalytic activity. We thus systematically evaluated a series of His- and Tyr-based peptides to identify sequence features for high-affinity heme binding and their impact on the catalytic activity of heme. METHODS We employed solid-phase peptide synthesis to produce 58 nonapeptides, which were investigated by UV/vis, resonance Raman, and 2D NMR spectroscopy. A chromogenic assay was used to determine the catalytic activity of the heme-peptide complexes. RESULTS Heme-binding affinity and binding mode were found to be dependent on the coordinating amino acid and spacer length between multiple potential coordination sites in a motif. In particular, HXH and HXXXH motifs showed strong heme binding. Analysis of the peroxidase-like activity revealed that some of these peptides and also HXXXY motifs enhance the catalytic activity of heme significantly. CONCLUSIONS We identify HXH, HXXXH, and HXXXY as potential new HRMs with functional properties. Several peptides displayed a strikingly high peroxidase-like activity. GENERAL SIGNIFICANCE The identification of HRMs allows to discover yet unknown heme-regulated proteins, and consequently, enhances our current understanding of pathologies involving labile heme.

中文翻译：

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基于 His/Tyr 的序列的高亲和力结合和催化活性：将血红素调节基序扩展到 CP 之外。

背景和动机肽和蛋白质可以通过血红素调节基序 (HRM) 中的 His、Tyr 或 Cys 与血红素相互作用。Cys-Pro 二肽是一种经过充分研究的 HRM，但对于 His 和 Tyr 来说，这种独特的基序目前尚不清楚。此外，许多血红素-肽复合物，如血红素-淀粉样蛋白β，可以表现出类似过氧化物酶的活性，尽管对局部一级和二级配位环境如何影响催化活性知之甚少。因此，我们系统地评估了一系列基于 His 和 Tyr 的肽，以确定高亲和力血红素结合的序列特征及其对血红素催化活性的影响。方法 我们采用固相肽合成方法制备了 58 个九肽，并通过紫外/可见光谱、共振拉曼光谱和二维核磁共振光谱对其进行了研究。显色测定用于确定血红素-肽复合物的催化活性。结果发现血红素结合亲和力和结合模式取决于基序中多个潜在配位位点之间的配位氨基酸和间隔物长度。特别是，HXH 和 HXXXH 基序显示出强烈的血红素结合。对过氧化物酶样活性的分析表明，这些肽中的一些以及 HXXXY 基序显着增强了血红素的催化活性。结论 我们将 HXH、HXXXH 和 HXXXY 确定为具有功能特性的潜在新 HRM。几种肽显示出惊人的高过氧化物酶样活性。一般意义 HRM 的鉴定允许发现未知的血红素调节蛋白，因此，增强了我们目前对涉及不稳定血红素的病理的理解。