201. N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor.
- Author
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Zhang H, Jing X, Shi Y, Xu H, Du J, Guan T, Weihrauch D, Jones DW, Wang W, Gourlay D, Oldham KT, Hillery CA, and Pritchard KA Jr
- Subjects
- Animals, Aorta cytology, Biocatalysis, Cattle, Endothelial Cells drug effects, Endothelial Cells metabolism, HL-60 Cells, Halogenation drug effects, Humans, Hypochlorous Acid metabolism, Lipid Peroxidation drug effects, Neutrophils enzymology, Nitrates metabolism, Oligopeptides metabolism, Oligopeptides toxicity, Oxidation-Reduction, Peroxidase metabolism, Oligopeptides pharmacology, Peroxidase antagonists & inhibitors
- Abstract
Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (≤4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HOCl generation by phorbol myristate acetate (PMA)-stimulated neutrophils and human promyelocytic leukemia (HL-60) cells but not superoxide generation by PMA-stimulated HL-60 cells. KYC inhibits MPO-mediated HOCl formation in BAEC culture and protects BAECs from MPO-induced injury. KYC inhibits MPO-mediated lipid peroxidation of LDL whereas tyrosine (Tyr) and tryptophan (Trp) enhance oxidation. KYC is unique as its isomers do not inhibit MPO activity, or are much less effective. Ultraviolet-visible spectral studies indicate KYC binds to the active site of MPO and reacts with compounds I and II. Docking studies show the Tyr of KYC rests just above the heme of MPO. Interestingly, KYC increases MPO-dependent H₂O₂ consumption. These data indicate KYC is a novel and specific inhibitor of MPO activity that is nontoxic to endothelial cell cultures. Accordingly, KYC may be useful for treating MPO-mediated vascular disease.
- Published
- 2013
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