Zusammenfassung
Soluble guanylyl cyclase (sGC) plays an important role in cardiovascular function and catalyzes formation of cGMP. sGC is activated by nitric oxide and allosteric stimulators and activators. However, despite its therapeutic relevance, the regulatory mechanisms of sGC are still incompletely understood. A major reason for this situation is that no crystal structures of active sGC have been resolved ...
Zusammenfassung
Soluble guanylyl cyclase (sGC) plays an important role in cardiovascular function and catalyzes formation of cGMP. sGC is activated by nitric oxide and allosteric stimulators and activators. However, despite its therapeutic relevance, the regulatory mechanisms of sGC are still incompletely understood. A major reason for this situation is that no crystal structures of active sGC have been resolved so far. An important step toward this goal is the identification of high-affinity ligands that stabilize an sGC conformation resembling the active, "fully closed" state. Therefore, we examined inhibition of rat sGC alpha(1)beta(1) by 38 purine- and pyrimidine-nucleotides with 2,4,6,-trinitrophenyl and (N-methyl) anthraniloyl substitutions at the ribosyl moiety and compared the data with that for the structurally related membranous adenylyl cyclases (mACs) 1, 2, 5 and the purified mAC catalytic subunits VC1:IIC2. TNP-GTP [2',3'-O-(2,4,6-trinitrophenyl)-GTP] was the most potent sGC alpha(1)beta(1) inhibitor (K-i, 10.7 nM), followed by 2'-MANT-3'-dATP [2'-O(N-methylanthraniloyl)-3'-deoxy-ATP] (K-i, 16.7 nM). Docking studies on an sGC alpha cat/sGC beta cat model derived from the inactive heterodimeric crystal structure of the catalytic domains point to similar interactions of (M) ANT-and TNP-nucleotides with sGC alpha(1)beta(1) and mAC VC1:IIC2. Reasonable binding modes of 2'-MANT-3'-dATP and bis-(M)ANT-nucleotides at sGC alpha(1)beta(1) require a 3'-endo ribosyl conformation (versus 3'-exo in 3'-MANT-2'-dATP). Overall, inhibitory potencies of nucleotides at sGC alpha(1)beta(1) versusmACs 1, 2, 5 correlated poorly. Collectively, we identified highly potent sGC alpha(1)beta(1) inhibitors that may be useful for future crystallographic and fluorescence spectroscopy studies. Moreover, it may become possible to develop mAC inhibitors with selectivity relative to sGC.
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