The myeloperoxidase system of human phagocytes generates Nε-(carboxymethyl)lysine on proteins:: a mechanism for producing advances glycation end products at sites of inflammation
The myeloperoxidase system of human phagocytes generates Nε-(carboxymethyl)lysine on proteins:: a mechanism for producing advances glycation end products at sites of inflammation
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DOI：
10.1172/jci3042
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发表时间：
1999-07-01
影响因子：
15.9
通讯作者：
Heinecke, JW
中科院分区：
文献类型：
--
作者：
Anderson, MM;Requena, JR;Heinecke, JW
来自还原糖和脂质过氧化的反应性醛共价修饰蛋白质，并可能导致氧化性组织损伤。我们最近描述了从游离α-氨基酸产生反应性醛的另一种机制。该途径始于髓过氧化物酶，一种由活化的中性粒细胞分泌的血红素酶。α-氨基酸转化为醛需要次氯酸（HOCl），由H2 O2和氯通过髓过氧化物酶形成。当L-丝氨酸是底物时，HOCl产生高产率的乙醇醛。我们现在证明，一个模型蛋白，核糖核酸酶A（RNase A），暴露于游离L-丝氨酸和HOCl表现出先进的糖化末端（AGE）产品的生化标志-布朗宁，荧光增强，交联。此外，当RNase A暴露于试剂HOCl-丝氨酸、髓过氧化物酶-H2 O2-氯化物系统加L-丝氨酸或活化的人中性粒细胞加L-丝氨酸时，在RNase A上产生了化学上充分表征的AGE产物N-α-（羧甲基）赖氨酸（CML）。中性粒细胞的CML生产被H2 O2清除剂过氧化氢酶和血红素毒物叠氮化物抑制，暗示髓过氧化物酶在细胞介导的反应中。当中性粒细胞在氨基酸混合物中被激活时，CML也通过髓过氧化物酶依赖性途径在RNA酶A上产生。在这些条件下，我们观察到L-丝氨酸依赖和L-丝氨酸不依赖的CML形成途径。髓过氧化物酶在体内产生乙醇醛和其他反应性醛类，因此可能通过产生AGE产物和损伤炎症部位的组织而发挥重要的致病作用。
Reactive aldehydes derived from reducing sugars and peroxidation of lipids covalently modify proteins and may contribute to oxidative tissue damage. We recently described another mechanism for generating reactive aldehydes from free alpha-amino acids. The pathway begins with myeloperoxidase, a heme enzyme secreted by activated neutrophils. Conversion of alpha-amino acids to aldehydes requires hypochlorous acid (HOCl), formed from H2O2 and chloride by myeloperoxidase. When L-serine is the substrate, HOCl generates high yields of glycolaldehyde. We now demonstrate that a model protein, ribonuclease A (RNase A), exposed to free L-serine and HOCl exhibits the biochemical hallmarks of advanced glycation end (AGE) products - browning, increased fluorescence, and cross-linking. Furthermore, N-epsilon-(carboxymethyl)lysine (CML), a chemically well-characterized AGE product, was generated on RNase A when it was exposed to reagent HOCl-serine, the myeloperoxidase-H2O2-chloride system plus L-serine, or activated human neutrophils plus L-serine. CML production by neutrophils was inhibited by the H2O2 scavenger catalase and the heme poison azide, implicating myeloperoxidase in the cell-mediated reaction. CML was also generated on RNase A by a myeloperoxidase-dependent pathway when neutrophils were activated in a mixture of amino acids. Under these conditions, we observed both L-serine-dependent and L-serine-independent pathways of CML formation. The in vivo production of glycolaldehyde and other reactive aldehydes by myeloperoxidase may thus play an important pathogenic role by generating AGE products and damaging tissues at sites of inflammation.