Peptides represent a large class of cell signaling molecules, and they are mainly produced by the classical secretory pathway or during protein degradation. The peptide profile of Danio rerio (zebrafish) shows a lack of information when compared with other consolidated animal models. The aim of this work was to characterize the peptide profile of zebrafish brain by using triplex reductive methylation of amines labeling and liquid chromatography coupled to electron spray mass spectrometry. A total of 411 peptide fragments were detected and 125 peptide sequences could be solved. Further analysis suggested that most of the peptides were fragments of intracellular cytosolic and mitochondrial proteins, and that 60% of the precursor proteins were cleaved at either their N- or C-terminal. The most common residue in the P1 position was leucine whereas other common residues were lysine, alanine, arginine, and phenylalanine. Rare cleavage sites at P1 position were histidine, glutamic acid, and isoleucine. The peptide profile of zebrafish brain has similarities with results previously described in mice brain peptidome studies. Thus, this study represents an important basis for the molecular understanding of zebrafish and its use as a model for human diseases.

中文翻译：

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斑马鱼大脑中的细胞内肽的表征。

肽代表一大类细胞信号分子，它们主要通过经典的分泌途径或在蛋白质降解过程中产生。与其他巩固动物模型相比，斑马鱼（Danio rerio）（斑马鱼）的肽谱显示缺乏信息。这项工作的目的是通过使用胺标记的三重还原甲基化和液相色谱与电子喷雾质谱联用来表征斑马鱼大脑的肽谱。共检测到411个肽段，可解析125个肽段序列。进一步的分析表明，大多数肽是细胞内胞质和线粒体蛋白的片段，并且60％的前体蛋白在其N端或C端均被切割。P1位置最常见的残基是亮氨酸，而其他常见残基是赖氨酸，丙氨酸，精氨酸和苯丙氨酸。P1位置的罕见切割位点是组氨酸，谷氨酸和异亮氨酸。斑马鱼脑的肽谱与先前在小鼠脑肽组研究中描述的结果相似。因此，这项研究代表了对斑马鱼的分子理解及其作为人类疾病模型的重要基础。