ABSTRACT
A series of hK6 inhibitors with a para-amidobenzylamine P1 group and a 2-hydroxybenzamide scaffold linker was discovered through virtual screening. The X-ray structure of hK6 complexed with compound 9b was determined to a resolution of 1.68Å. The tertiary folding of the hK6 complexed with the inhibitor is conserved relative to the structure of the apo-protein, whereas the interaction between hK6 and the inhibitor is consistent with both the SAR and the in silico model used in the virtual screening.
Subject(s)
Benzamides/chemistry , Benzylamines/chemistry , Kallikreins/chemistry , Models, Molecular , Serine Proteinase Inhibitors/chemistry , Benzylamines/pharmacology , Binding Sites , Computer Simulation , Crystallography, X-Ray , Humans , Kallikreins/antagonists & inhibitors , Protein Binding , Protein Folding , Protein Structure, Tertiary , Serine Proteinase Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
A series of compounds with an amidinothiophene P1 group and a pyrrolidinone-sulphonamide scaffold linker was identified as potent inhibitors of human kallikrein 6 by structure-based virtual screening based on the union accessible binding space of serine proteases. As the first series of potent nonmechanism-based hK6 inhibitors, they may be used as tool compounds for target validation. An X-ray structure of a representative compound complexed with hK6, resolved at a resolution of 1.88 Å, revealed that the amidinothiophene moiety bound in the S1 pocket and the pyrrolidinone-sulphonamide linker projected the aromatic tail into the S' pocket.
ABSTRACT
A solid phase combinatorial library was designed based on X-ray structures and in-silico models to explore an inducible S4+ pocket, which is formed by a simple side-chain rotation of Tyr95. This inducible S4+ pocket is unique to ß-tryptase and does not exist for other trypsin-like serine proteases of interest. Therefore, inhibitors utilizing this pocket have inherent advantages for being selective against other proteases in the same family. A member of this library was found to be a potent and selective ß-tryptase inhibitor with a suitable pharmacokinetic profile for further clinical evaluation.
Subject(s)
Enzyme Inhibitors/pharmacology , Mast Cells/enzymology , Small Molecule Libraries/pharmacology , Tryptases/antagonists & inhibitors , Administration, Oral , Animals , Combinatorial Chemistry Techniques , Crystallography, X-Ray , Dose-Response Relationship, Drug , Enzyme Inhibitors/administration & dosage , Enzyme Inhibitors/chemical synthesis , Humans , Models, Molecular , Molecular Structure , Rats , Recombinant Proteins/antagonists & inhibitors , Small Molecule Libraries/administration & dosage , Small Molecule Libraries/chemical synthesis , Structure-Activity RelationshipABSTRACT
Tryptase is a serine protease found almost exclusively in mast cells. It has trypsin-like specificity, favoring cleavage of substrates with an arginine (or lysine) at the P1 position, and has optimal catalytic activity at neutral pH. Current evidence suggests tryptase beta is the most important form released during mast cell activation in allergic diseases. It is shown to have numerous pro-inflammatory cellular activities in vitro, and in animal models tryptase provokes broncho-constriction and induces a cellular inflammatory infiltrate characteristic of human asthma. Screening of in-house inhibitors of factor Xa (a closely related serine protease) identified beta-amidoester benzamidines as potent inhibitors of recombinant human betaII tryptase. X-ray structure driven template modification and exchange of the benzamidine to optimize potency and pharmacokinetic properties gave selective, potent and orally bioavailable 4-(3-aminomethyl phenyl)piperidinyl-1-amides.
