Deletion of the autoregulatory insert modulates intraprotein electron transfer in rat neuronal nitric oxide synthase.
Comparative CO photolysis kinetics studies on wild-type and autoregulatory (AR) insert-deletion mutant of rat nNOS holoenzyme were conducted to directly investigate the role of the unique AR insert in the catalytically significant FMN-heme intraprotein electron transfer (IET). Although the amplitude of the IET kinetic traces was decreased two- to three-fold, the AR deletion did not change the rate constant for the calmodulin-controlled IET. This suggests that the rate-limiting conversion of the electron-accepting state to a new electron-donating (output) state does not involve interactions with the AR insert, but that AR may stabilize the output state once it is formed.
Feng
Changjian
C
College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, United States. cfeng@salud.unm.edu
Roman
Linda J
LJ
Hazzard
James T
JT
Ghosh
Dipak K
DK
Tollin
Gordon
G
Masters
Bettie Sue S
BS
D000818:Animals; D002147:Calmodulin / Q000737:chemistry; D004579:Electron Transport; D005486:Flavin Mononucleotide / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D006706:Homeostasis; D054643:INDEL Mutation; D019001:Nitric Oxide Synthase / Q000737:chemistry* / Q000235:genetics; D052248:Nitric Oxide Synthase Type I; D010782:Photolysis; D017434:Protein Structure, Tertiary; D051381:Rats
D002147:Calmodulin; D006418:Heme; D005486:Flavin Mononucleotide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat