Signal discrimination analyses based on the domain structure of soluble guanylate cyclase

我们发现在可溶性鸟苷酸环化酶中存在两种核苷酸结合位点，一种是催化位点，另一种是伪核苷酸结合位点。当一氧化碳与酶血红素结合时，YC-1与伪核苷酸结合位点的结合通过两个结合位点之间的相互作用增加了核苷酸对伪核苷酸结合位点的亲和力。此外，我们首次证实了酶的氧合形式的形成，它在冷冻条件下是稳定的。根据EXAFS分析，氧合形式的形成是由YC-1结合调节的，也被认为是由血红素平面上血红素铁的变形控制的。

We have revealed that there were two kinds of nucleotide binding sites, a catalytic and a pseudo-nucleotide sites in soluble guanylate cyclase. When carbon monoxide combined to the enzymic heme, the binding of YC-1 to the pseudo-nucleotide binding site increased the affinity of a nucleotide for the pseudo nucleotide binding site, through interaction between two binding sites. Furthermore, we have first confirmed the formation of the oxygenated form of the enzyme, which was stable under frozen conditions. The formation of the oxygenated form was noted to be regulated by YC-1 binding, and also was suggested to be governed by the deformation of the heme iron from the heme plane, based on the EXAFS analyses.