Human peroxidasin 1 (PXDN) is a homotrimeric multidomain heme peroxidase and essential for tissue development and architecture. It has a biosynthetic function and catalyses the hypobromous acid-mediated formation of specific covalent sulfilimine (SN) bonds, which cross-link type IV collagen chains in basement membranes. Currently, it is unknown whether and which domain(s) [i.e. leucine-rich repeat domain (LRR), immunoglobulin domains, peroxidase domain, von Willebrand factor type C domain] of PXDN interact with the polymeric networks of the extracellular matrix (ECM), and how these interactions integrate and regulate the enzyme's cross-linking activity, without imparting oxidative damage to the ECM. In this study, we probed the interactions of four PXDN constructs with different domain compositions with components of a basement membrane extract by immunoprecipitation. Strong binding of the LRR-containing construct was detected with the major ECM protein laminin. Analysis of these interactions by surface plasmon resonance spectroscopy revealed similar kinetics and affinities of binding of the LRR-containing construct to human and murine laminin-111, with calculated dissociation constants of 1.0 and 1.5 μM, respectively. The findings are discussed with respect to the recently published in-solution structures of the PXDN constructs and the proposed biological role of this peroxidase.

人过氧化物酶 1 (PXDN) 是一种同源三聚体多结构域血红素过氧化物酶，对组织发育和结构至关重要。它具有生物合成功能并催化次溴酸介导的特定共价硫亚胺 (SN) 键，它在基底膜中交联 IV 型胶原蛋白链。目前，尚不清楚 PXDN 的哪些结构域（即富含亮氨酸的重复结构域 (LRR)、免疫球蛋白结构域、过氧化物酶结构域、血管性血友病因子 C 型结构域）是否与细胞外基质 (ECM) 的聚合网络相互作用以及相互作用。 ，以及这些相互作用如何整合和调节酶的交联活性，而不会对 ECM 造成氧化损伤。在这项研究中，我们通过免疫沉淀探索了四种具有不同结构域组成的 PXDN 构建体与基底膜提取物成分的相互作用。检测到含有 LRR 的构建体与主要 ECM 蛋白层粘连蛋白的强结合。通过表面等离子共振光谱分析这些相互作用揭示了含有 LRR 的构建体与人和鼠 laminin-111 结合的相似动力学和亲和力，计算的解离常数分别为 1.0 和 1.5 μM。关于最近发表的 PXDN 构建体的溶液内结构和该过氧化物酶的拟议生物学作用，讨论了这些发现。