Myeloperoxidase-mediated oxidation of methionine

✍ Scribed by Min-Fu Tsan

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 699 KB
• Volume: 111
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1041110109

✦ Synopsis

The rnyeloperoxidase-mediated oxidation of methionine was studied using a purified canine myeloperoxidase preparation. The system required the simultaneous presence of myeloperoxidase, H202, and a halide anion. When 0.1 mM H 2 0 2 was used, the system has a pH optimum of approximately pH 5-5.5. Bromide and iodide were much more effective than chloride in the myeioperoxidase-mediated oxidation of methionine. Horseradish peroxidase was unable to oxidize methionine whether chloride or iodide was used. In contrast, lactoperoxidase oxidized methionine in the presence of iodide but not chloride.

Based on studies of 1) the effect of various inhibitors and singlet oxygen quenchers, as well as 2) the effect of D 2 0 on the oxidation of me~hionine, by the rnyeloperoxidase system, OCI-, or methylene blue, it was shown that the oxidation of methionine by the myeloperoxidase system was not mediated by OCIor lo2. The mechanism of the myeloperoxidase-mediated oxidation of methionine remains unclear. However, it may be one mechanism by which the myeloperoxidase system damage microorganisms.