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Brain nitric oxide synthase is a biopterin‐ and flavin‐containing multi‐functional oxido‐reductase
Author(s) -
Mayer Bernd,
John Mathias,
Heinzel Burghard,
Werner Ernst R.,
Wachter Helmut,
Schultz Günter,
Böhme Eycke
Publication year - 1991
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(91)81031-3
Subject(s) - tetrahydrobiopterin , cofactor , chemistry , nitric oxide synthase , nos1 , enzyme , biopterin , biochemistry , atp synthase , calmodulin , arginine , flavin group , heme , flavin adenine dinucleotide , reductase , amino acid
Brain nitric oxide synthase is a Ca 2+ /calmodulin‐regulated enzyme which converts L‐arginine into NO. Enzymatic activity of this enzyme essentially depends on NADPH and is stimulated by tetrahydrobiopterin (H 4 biopterin). We found that purified NO synthase contains enzyme‐bound H 4 biopterin, explaining the enzymatic activity observed in the absence of added cofactor. Together with the finding that H 4 biopterin was effective at substoichiometrical concentrations, these results indicate that NO synthase essentially depends on H 4 biopterin as a cofactor which is recycled during enzymatic NO formation. We found that the purified enzyme also contains FAD, FMN and non‐heme iron in equimolar amounts and exhibits striking activities, including a Ca 2+ /calmodulin‐dependent NADPH oxidase activity, leading to the formation of hydrogen peroxide at suboptimal concentrations of L‐arginine or H 4 biopterin.