Activation of soluble guanylyl cyclase by four-coordinate metalloporphyrins: evidence for a role for porphyrin conformation

Results point out that the presence of the heme b and the absence of a metal histidine bond are involved in the the activation of soluble guanylyl cyclase. Further, the metalloprotein porphyrins serve as activators and are bound 4-coordinate to the enzyme, suggesting that the tetrapyrrole conformation is important.