SCHEME 2.
Kinetic scheme of nucleotide regulation of sGC. Equilibria scheme for sGC (E) with one active site and one regulating allosteric site, binding to substrate (GTP) and inhibitor (ATP). Binding of GTP to the active site composes an active complex (EGTP) producing product (cGMP). Binding of ATP to the allosteric site (ATPE) affects the affinity of the active site for GTP by a factor of α. ATPEGTP and GTPEGTP have a different rate of product formation (βkp and γkp, respectively) than EGTP (kp). Ksc, Ksa, Kic, and Kia are the dissociation constants of the EGTP, GTPE, EATP, and ATPE complexes.