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Abstract：
The interplay between metal ion binding and the activity of thiol proteins, particularly within the protein disulfide isomerase family, remains an area of active investigation due to the critical role that these proteins play in many vital processes. This research investigates the interaction between recombinant human PDIA1 and zinc ions, focusing on the subsequent implications for PDIA1\'s conformational stability and enzymatic activity. Employing isothermal titration calorimetry and differential scanning calorimetry, we systematically compared the zinc binding capabilities of both oxidized and reduced forms of PDIA1 and assessed the structural consequences of this interaction. Our results demonstrate that PDIA1 can bind zinc both in reduced and oxidized states, but with significantly different stoichiometry and more pronounced conformational effects in the reduced form of PDIA1. Furthermore, zinc binding was observed to inhibit the catalytic activity of reduced-PDIA1, likely due to induced alterations in its conformation. These findings unveil a potential regulatory mechanism in PDIA1, wherein metal ion binding under reductive conditions modulates its activity. Our study highlights the potential role of zinc in regulating the catalytic function of PDIA1 through conformational modulation, suggesting a nuanced interplay between metal binding and protein stability in the broader context of cellular redox regulation.
摘要：
金属离子结合与硫醇蛋白活性之间的相互作用，特别是在蛋白质二硫键异构酶家族中，由于这些蛋白质在许多重要过程中发挥关键作用，因此仍然是活跃研究的领域。这项研究调查了重组人PDIA1与锌离子之间的相互作用，重点关注PDIA1的构象稳定性和酶活性的后续含义。采用等温滴定量热法和差示扫描量热法，我们系统地比较了PDIA1的氧化和还原形式的锌结合能力,并评估了这种相互作用的结构后果.我们的结果表明，PDIA1可以在还原和氧化态结合锌，但在还原形式的PDIA1中具有明显不同的化学计量和更明显的构象效应。此外，观察到锌结合抑制还原PDIA1的催化活性，这可能是由于其构象的诱导改变。这些发现揭示了PDIA1中的潜在调节机制,其中在还原条件下的金属离子结合调节其活性。我们的研究强调了锌在通过构象调节PDIA1的催化功能中的潜在作用，表明在细胞氧化还原调节的更广泛背景下，金属结合和蛋白质稳定性之间存在微妙的相互作用。
