HUMAN NEUTROPHILS: PROTEIN MODIFICATION & SIGNALING AT SITES OF INFLAMMATION

我们最近已经证明，激活的吞噬细胞利用 血红素蛋白髓过氧化物酶、过氧化氢和氯离子氧化芳香族 氨基酸L-酪氨酸转化为反应醛 对羟基苯乙醛。该产品是以高成品率成型的， 这表明其他氨基酸可能类似地被氧化成它们的 炎症部位的吞噬细胞产生相应的醛。我们 现在提出证据证明这种反应的普遍性，通过 证明中性粒细胞利用 髓过氧化物酶-过氧化氢-氯离子体系氧化几乎所有常见的 A-氨基酸生成一系列反应性醛。化学制品 表征表明，反应性羰基部分是 在髓过氧化物酶氧化氨基酸的过程中产生。这个 氨基酸衍生的醛的结构得到了确证。 各种质谱学方法。需要乙醛生产 髓过氧化物酶、过氧化氢、氯离子和一种氨基酸；它被血红素抑制 毒药和过氧化氢酶。次氯亚酸(HOCl)是最明显的 氧化中间体，因为它与a-氨基酸的加成导致 在预期的醛的形成中。受刺激的人 中性粒细胞同样会从所有类别的a-氨基中产生醛。 被血红素毒物和过氧化氢酶抑制的酸类，暗示 髓过氧化物酶和过氧化氢在细胞介导的反应中的作用。乙醛 产生的过氧化氢占到了由 以生理浓度的氨基酸刺激中性粒细胞。 总而言之，这些结果表明氨基酸衍生的醛 代表一大类活性物种，这些活性物种由 吞噬细胞。氨基酸氧化过程中产生的醛可能 构成了一种重要的信号传递机制和选择性 炎症和血管部位的关键靶点损伤 疾病。

We have recently demonstrated that activated phagocytes employ the heme protein myeloperoxidase, H2O2 and Cl- to oxidize the aromatic amino acid L-tyrosine to the reactive aldehyde p-hydroxyphenylacetaldehyde. The product is formed in high yield, suggesting that other amino acids might similarly be oxidized to their corresponding aldehydes by phagocytes at sites of inflammation. We now present evidence for the generality of this reaction by demonstrating that neutrophils employ the myeloperoxidase-H2O2-Cl-system to oxidize nearly all of the common a-amino acids to generate a family of reactive aldehydes. Chemical characterization suggested that reactive carbonyl moieties were generated during amino acid oxidation by myeloperoxidase. The structures of amino acid-derived aldehydes were confirmed using a variety of mass spectrometric methods. Aldehyde production required myeloperoxidase, H2O2, Cl- and an amino acid; it was inhibited by heme poisons and catalase. Hypochlor ous acid (HOCl) was the apparent oxidizing intermediate because its addition to a-amino acids resulted in the formation of the anticipated aldehyde. Stimulated human neutrophils likewise generated aldehydes from all classes of a-amino acids by a pathway inhibited by heme poisons and catalase, implicating myeloperoxidase and H2O2 in the cell-mediated reaction. Aldehyde production accounted for up to 70 % of the H2O2 generated by stimulated neutrophils at physiological concentrations of amino acids. Collectively, these results suggest that amino acid-derived aldehydes represent a major class of reactive species generated by activated phagocytes. Aldehyde production during amino acid oxidation may constitute an important mechanism for signaling and the selective damage of critical targets at sites of inflammation and vascular disease.