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Tris(picolinato)manganese(II): a chemical model for the mechanism and function of mitochondrial superoxide dismutase
Author(s) -
Yamaguchi Kenneth S.,
Spencer Lee,
Sawyer Donald T.
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80336-2
Subject(s) - chemistry , disproportionation , superoxide dismutase , protonation , manganese , medicinal chemistry , radical , tris , hydrogen atom abstraction , superoxide , allylic rearrangement , photochemistry , enzyme , biochemistry , organic chemistry , catalysis , ion
The reaction of HO 2 . with the allylic groups of lipids initiates their peroxidation and auto‐oxidation, and probably represents the most serious biological hazard of O 2 .− ‐derived species. The presence of tris(picolinato) manganese(II) [Mn II (PA) 2 (PAH)(H 2 O)], a model complex for mitochondrial Superoxide dismutase, (i) efficiently catalyzes the disproportionation of O 2 .− , (ii) precludes the formation HO 2 . , and thereby (iii) prevents hydrogen abstraction from allylic and thiol groups. Such protection demonstrates that a primary function of superoxide dismutase is to block the formation of HO 2 . , which is the obligatory intermediate for the nonenzymatic proton‐induced disproportionation process. This requires that the primary step for the enzyme‐O 2 .− reaction be kinetically favored and dominant relative to the protonation reaction (HA + O 2 .− ).