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. Author manuscript; available in PMC: 2013 Dec 1.
Published in final edited form as: Arch Biochem Biophys. 2012 Sep 11;528(1):72–89. doi: 10.1016/j.abb.2012.09.002

Figure 14.

Figure 14

Proposed model for CaM-mediated regulation of NOS. (A) The conformational rearrangements of functional domains in the NOS dimer. H1 indicates the hinge between the FMN- and FAD domains, and H2 represents the hinge between the FMN- and heme domains. Upon binding to CaM, H2 is divided into H2a and H2b. (B) Mechanism of redox-linked conformational selection. Positive (plus) and negative (minus) surface charges of the FAD-, FMN-, and heme domains are indicated in red. The blue dots indicate hydrated water molecules; the FMN semiquinone state has a tighter water-network. Upon futher reduction of the semiquinone to fully reduced, FMNH− state, the water-network becomes loose and more flexible [179]. In the protein-protein interface between heme and FMN domains of nNOS, the following residues are involved in these electrostatic interactions: Lys423, Lys620, Lys660 (heme domain) and Glu762, Asp813, Glu816, and Glu819 (FMN domain) [175].