Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10574024 | Journal of Inorganic Biochemistry | 2005 | 13 Pages |
Abstract
Soluble guanylate cyclase (sGC, EC 4.6.1.2) acts as a sensor for nitric oxide (NO), but is also activated by carbon monoxide in the presence of an allosteric modulator. Resonance Raman studies on the structure-function relations of sGC are reviewed with a focus on the CO-adduct in the presence and absence of allosteric modulator, YC-1, and substrate analogues. It is demonstrated that the sGC isolated from bovine lung contains one species with a five-coordinate (5c) ferrous high-spin heme with the Fe-His stretching mode at 204 cmâ1, but its CO adduct yields two species with different conformations about the heme pocket with the Fe-CO stretching (νFe-CO) mode at 473 and 489 cmâ1, both of which are His- and CO-coordinated 6c ferrous adducts. Addition of YC-1 to it changes their population and further addition of GTP yields one kind of 6c (νFe-CO = 489 cmâ1) in addition to 5c CO-adduct (νFe-CO = 521 cmâ1). Under this condition the enzymatic activity becomes nearly the same level as that of NO adduct. Addition of γ-S-GTP yields the same effect as GTP does but cGMP and GDP gives much less effects. Unexpectedly, ATP cancels the effects of GTP. The structural meaning of these spectroscopic observations is discussed in detail.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Inorganic Chemistry
Authors
Biswajit Pal, Teizo Kitagawa,