Mechanism of binding of NO to soluble guanylyl cyclase: implication for the second NO binding to the heme proximal site.

ABSTRACT: Soluble guanylyl cyclase (sGC), the key enzyme for the formation of second messenger cyclic GMP, is an authentic sensor for nitric oxide (NO). Binding of NO to sGC leads to strong activation of the enzyme activity. Multiple molecules and steps of binding of NO to sGC have been implicated, but the target of the second NO and the detailed binding mechanism remain controversial. In this study, we used (15)NO and (14)NO and anaerobic sequential mixing-freeze-quench electron paramagnetic resonance to unambiguously confirm that the heme Fe is the target of the second NO. The linear dependence on NO concentration up to 600 s(-1) for the observed rate of the second step of NO binding not only indicates that the binding site of the second NO is different from that in the first step, i.e., the proxi

SUBMITTER: Martin E 

PROVIDER: S-EPMC3319481 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature