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Abstract：
Protein persulfidation is a thiol-based oxidative posttranslational modification (oxiPTM) that involves the modification of susceptible cysteine thiol groups present in peptides and proteins through hydrogen sulfide (H2S), thus affecting their function. Using sweet pepper (Capsicum annuum L.) fruits as a model material at different stages of ripening (immature green and ripe red), endogenous persulfidated proteins (persulfidome) were labeled using the dimedone switch method and identified using liquid chromatography and mass spectrometry analysis (LC-MS/MS). A total of 891 persulfidated proteins were found in pepper fruits, either immature green or ripe red. Among these, 370 proteins were exclusively present in green pepper, 237 proteins were exclusively present in red pepper, and 284 proteins were shared between both stages of ripening. A comparative analysis of the pepper persulfidome with that described in Arabidopsis leaves allowed the identification of 25% of common proteins. Among these proteins, glutathione reductase (GR) and leucine aminopeptidase (LAP) were selected to evaluate the effect of persulfidation using an in vitro approach. GR activity was unaffected, whereas LAP activity increased by 3-fold after persulfidation. Furthermore, this effect was reverted through treatment with dithiothreitol (DTT). To our knowledge, this is the first persulfidome described in fruits, which opens new avenues to study H2S metabolism. Additionally, the results obtained lead us to hypothesize that LAP could be involved in glutathione (GSH) recycling in pepper fruits.
摘要：
蛋白质过硫化是一种基于硫醇的氧化翻译后修饰（oxiPTM），涉及通过硫化氢（H2S）修饰肽和蛋白质中存在的易感半胱氨酸硫醇基团，从而影响其功能。在成熟的不同阶段（未成熟的绿色和成熟的红色），使用甜椒（CapsicumannuumL.）果实作为模型材料，使用dimedone开关方法标记内源性过硫化蛋白(过硫化蛋白),并使用液相色谱和质谱分析(LC-MS/MS)进行鉴定.在辣椒果实中发现了891种过硫化蛋白,未成熟的绿色或成熟的红色。其中,370种蛋白质只存在于青椒中，红辣椒中只存在237种蛋白质，在两个成熟阶段之间共有284种蛋白质。对拟南芥叶片中的胡椒过硫化物进行比较分析，可以鉴定出25％的常见蛋白质。在这些蛋白质中，选择谷胱甘肽还原酶（GR）和亮氨酸氨基肽酶（LAP）来使用体外方法评估过硫化的效果。GR活性未受影响，而LAP活性在过硫化后增加了3倍。此外，通过使用二硫苏糖醇(DTT)治疗,这一效应得以逆转.据我们所知,这是水果中描述的第一个过硫化物圆顶，这为研究H2S代谢开辟了新的途径。此外,获得的结果使我们假设LAP可能参与辣椒果实中谷胱甘肽（GSH）的回收。
