The function of endogenous cell-cell signaling peptides relies on their interactions with cognate receptors, which in turn are influenced by the peptides' structures, necessitating a comprehensive understanding of the suite of post-translational modifications of the peptide. Herein, we report the initial characterization of putative peptide isomerase enzymes extracted from , , and tissues. These enzymes are both tissue and substrate-specific across all three organisms. Notably, the lungs of the mammalian species, and the central nervous system of the mollusk displayed the highest isomerase activity among the examined tissues. enzymatic conversion was observed for several endogenous peptides, such as the tetrapeptide GFFD in , and mammalian neuropeptide FF in and . To understand their mode of action, we explored the effects of several inhibitors on these enzymes, which suggest common active site residues. While further characterization of these enzymes is required, the investigations emphasize a widespread and overlooked enzyme activity related to the creation of bioactive peptides.

中文翻译：

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一系列新型后生动物 L/D 肽异构酶


内源性细胞间信号肽的功能依赖于它们与同源受体的相互作用，而同源受体又受到肽结构的影响，因此需要全面了解肽的一系列翻译后修饰。在此，我们报告了从 、 和 组织中提取的假定肽异构酶的初步表征。这些酶在所有三种生物体中都是组织和底物特异性的。值得注意的是，哺乳动物的肺和软体动物的中枢神经系统在检查的组织中表现出最高的异构酶活性。观察到几种内源肽的酶促转化，例如 中的四肽 GFFD 和 中的哺乳动物神经肽 FF。为了了解它们的作用方式，我们探索了几种抑制剂对这些酶的影响，这表明了常见的活性位点残基。虽然需要对这些酶进行进一步表征，但研究强调了与生物活性肽的产生相关的广泛且被忽视的酶活性。