Interactions between cyclic nucleotide phosphodiesterase 11 catalytic site and substrates or tadalafil and role of a critical Gln-869 hydrogen bond.

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Weeks JL 2nd, Corbin JD, Francis SH

Interactions between cyclic nucleotide phosphodiesterase 11 catalytic site and substrates or tadalafil and role of a critical Gln-869 hydrogen bond.

J Pharmacol Exp Ther. 2009 Oct;331(1):133-41. doi: 10.1124/jpet.109.156935. Epub 2009 Jul 29.

PubMed ID

19641165 [ View in PubMed

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Abstract

Poor understanding of the topography of cyclic nucleotide (CN) phosphodiesterase (PDE) catalytic sites compromises development of potent, selective inhibitors for therapeutic use. In the X-ray crystal structures of the catalytic domains of some PDEs, an invariant glutamine hydrogen bonds with groups at C6 and N1 or N7 on catalytic products or analogous positions of some inhibitors, inferring similar bonds with CNs (Nature 425:98-102, 2003; J Mol Biol 337:355-365, 2004; Mol Cell 15:279-286, 2004). A site-directed mutant (Q869A) lacking this invariant Gln in cGMP-/cAMP-hydrolyzing PDE11 had unaltered catalytic activity and affinity for sildenafil; but cGMP/cAMP or tadalafil affinity was reduced approximately 50- or 140-fold, respectively, and calculated free energy of binding suggested one hydrogen bond for each. A cGMP analog lacking the C6 oxygen had approximately 80-fold weakened affinity, modifications at N(2), N7, or 2'-OH diminished affinity approximately 16-fold, and analogs with groups appended at N1 had only 2- to 6-fold weakened affinity. Analogs with C8 substitutions were ineffective inhibitors, suggesting that cGMP binds in the anti conformation. Calculated decline in free energy of binding was consistent with that for one hydrogen bond only in the analog lacking binding potential at C6. In conclusion, Gln-869 interacts strongly with cGMP/cAMP and tadalafil, but not with sildenafil; interactions with CN analogs suggest a hydrogen bond only between Gln-869 and the C6 substituent. The results define interactions between the PDE11 catalytic site and substrates/inhibitors and advance potential for inhibitor design.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Tadalafil	Dual 3',5'-cyclic-AMP and -GMP phosphodiesterase 11A	Protein	Humans	No	Inhibitor	Details