The 2-hydroxy-4-methoxybenzyl (Hmb) backbone modification can prevent amide bond-mediated side-reactions (, aspartimide formation, peptide aggregation) by installing the removable Hmb group into a peptide bond, thus improving the synthesis of long and challenging peptides and proteins. However, its use is largely precluded by the limited Hmb's installation sites. In this report, an improved installation of Hmb (iHmb) method was developed to achieve the flexible installation and the convenient removal of Hmb. The iHmb method involves two critical steps: (1) oxidative diazotization of the readily installed 2-hydroxy-4-methoxy-5-amino-benzyl (Hmab) to give 2-hydroxy-4-methoxy-5-diazonium-benzyl (Hmdab) by combining soamyl nitrite (IAN)/HBF, and (2) reductive elimination of Hmdab to give the desired Hmb by 1,2-ethanedithiol (EDT). The iHmb method enables the installation of Hmb at any primary amino acid including the highly sterically hindered amino acids (, valine and isoleucine). The practicality and utility of the iHmb method was demonstrated by one-shot solid-phase synthesis of a challenging aspartimide-prone peptide, the mirror-image version of a hydrophobic peptide and a long-chain peptide up to 76-residue. Furthermore, the iHmb method can be utilized to facilitate chemical protein ligation, as exemplified by the synthesis of the single-spanning membrane protein sarcolipin. The iHmb method expands the toolkit for peptide synthesis and ligation and facilitates the preparation of peptides/proteins.

中文翻译：

---

用于化学蛋白质合成的 2-羟基-4-甲氧基苄基 (iHmb) 方法的改进装置

2-羟基-4-甲氧基苄基 (Hmb) 主链修饰可以通过将可去除的 Hmb 基团安装到肽键中来防止酰胺键介导的副反应（天冬酰亚胺形成、肽聚集），从而改善长且具有挑战性的肽的合成和蛋白质。然而，由于 Hmb 的安装地点有限，其使用在很大程度上受到阻碍。本报告提出了一种改进的Hmb安装方法（iHmb），以实现Hmb的灵活安装和方便拆卸。 iHmb 方法涉及两个关键步骤：（1）将易于安装的 2-羟基-4-甲氧基-5-氨基-苄基（Hmab）氧化重氮化，得到 2-羟基-4-甲氧基-5-重氮-苄基（Hmdab） )通过组合亚硝酸异戊酯(IAN)/HBF，和(2)通过1,2-乙二硫醇(EDT)还原消除Hmdab以得到所需的Hmb。 iHmb 方法能够将 Hmb 安装在任何一级氨基酸上，包括高度空间位阻的氨基酸（缬氨酸和异亮氨酸）。 iHmb 方法的实用性和实用性通过一次性固相合成具有挑战性的天冬酰亚胺倾向肽、疏水性肽的镜像版本和最多 76 个残基的长链肽来证明。此外，iHmb 方法可用于促进化学蛋白质连接，例如单跨膜蛋白肌脂蛋白的合成。 iHmb方法扩展了肽合成和连接的工具包，并促进了肽/蛋白质的制备。