Enantiomer discrimination illustrated by the high resolution crystal structures of type 4 phosphodiesterase.
Type 4 phosphodiesterase (PDE4) inhibitors are emerging as new treatments for a number of disorders including asthma and chronic obstructive pulmonary disease. Here we report the biochemical characterization on the second generation inhibitor (+)-1 (L-, IC50=0.4 nM) and its enantiomer (-)-1 (L-, IC50=43 nM) and their cocrystal structures with PDE4D at 2.0 A resolution. Despite the 107-fold affinity difference, both enantiomers interact with the same sets of residues in the rigid active site. The weaker (-)-1 adopts an unfavorable conformation to preserve the pivotal interactions between the Mg-bound waters and the N-oxide of pyridine. These structures support a model in which inhibitors are anchored by the invariant glutamine at one end and the metal-pocket residues at another end. This model provides explanations for most of the observed structure-activity relationship and the metal ion dependency of the catechol-ether based inhibitors and should facilitate their further design.
Huai
Qing
Q
Department of Biochemistry and Biophysics and Lineberger Comprehensive Cancer Center, The University of North Carolina, Chapel Hill, North Carolina 27599-7260, USA.
Sun
Yingjie
Y
Wang
Huanchen
H
Macdonald
Dwight
D
Aspiotis
Renée
R
Robinson
Howard
H
Huang
Zheng
Z
Ke
Hengming
H
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D003497:Cyclic N-Oxides / Q000737:chemistry*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004791:Enzyme Inhibitors / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D011485:Protein Binding; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism
D003497:Cyclic N-Oxides; D004791:Enzyme Inhibitors; C475430:L 869298; D011725:Pyridines; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4