Electron transfer in a human inducible nitric oxide synthase oxygenase/FMN construct co-expressed with the N-terminal globular domain of calmodulin.
The FMN-heme intraprotein electron transfer (IET) kinetics in a human inducible NOS (iNOS) oxygenase/FMN (oxyFMN) construct co-expressed with NCaM, a truncated calmodulin (CaM) construct that includes only its N-terminal globular domain consisting of residues 1-75, were determined by laser flash photolysis. The IET rate constant is significantly decreased by nearly fourfold (compared to the iNOS oxyFMN co-expressed with full length CaM). This supports an important role of full length CaM in proper interdomain FMN/heme alignment in iNOS. The IET process was not observed with added excess EDTA, suggesting that Ca(2+) depletion results in the FMN domain moving away from the heme domain. The results indicate that a Ca(2+)-dependent reorganization of the truncated CaM construct could cause a major modification of the NCaM/iNOS association resulting in a loss of the IET.
Feng
Changjian
C
College of Pharmacy, University of New Mexico, Albuquerque, NM 87131, USA. cfeng@salud.unm.edu
Fan
Weihong
W
Dupont
Andrea
A
Guy Guillemette
J
J
Ghosh
Dipak K
DK
Tollin
Gordon
G
D001665:Binding Sites / Q000235:genetics; D002118:Calcium / Q000378:metabolism; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology; D003001:Cloning, Molecular; D004492:Edetic Acid / Q000494:pharmacology; D004579:Electron Transport / Q000187:drug effects; D005486:Flavin Mononucleotide / Q000737:chemistry / Q000378:metabolism*; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D017942:Nitric Acid / Q000737:chemistry / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010777:Photochemistry; D010782:Photolysis / Q000187:drug effects
D002147:Calmodulin; D002614:Chelating Agents; D017942:Nitric Acid; D006418:Heme; D005486:Flavin Mononucleotide; D004492:Edetic Acid; D052247:Nitric Oxide Synthase Type II; D006419:Heme Oxygenase (Decyclizing); D002118:Calcium