Dale R. Cameron

An NS3 protease inhibitor with antiviral effects in humans infected with hepatitis C virus

Hepatitis C virus (HCV) infection is a serious cause of chronic liver disease worldwide with more than 170 million infected individuals at risk of developing significant morbidity and mortality. Current interferon-based therapies are suboptimal especially in patients infected with HCV genotype 1, and they are poorly tolerated, highlighting the unmet medical need for new therapeutics. The HCV-encoded NS3 protease is essential for viral replication and has long been considered an attractive target for therapeutic intervention in HCV-infected patients. Here we identify a class of specific and potent NS3 protease inhibitors and report the evaluation of BILN 2061, a small molecule inhibitor biologically available through oral ingestion and the first of its class in human trials. Administration of BILN 2061 to patients infected with HCV genotype 1 for 2 days resulted in an impressive reduction of HCV RNA plasma levels, and established proof-of-concept in humans for an HCV NS3 protease inhibitor. Our results further illustrate the potential of the viral-enzyme-targeted drug discovery approach for the development of new HCV therapeutics.

Solution Structure of Substrate-based Ligands When Bound to Hepatitis C Virus NS3 Protease Domain

The interactions of the NS3 protease domain with inhibitors that are based on N-terminal cleavage products of peptide substrates were studied by NMR methods. Transferred nuclear Overhauser effect experiments showed that these inhibitors bind the protease in a well defined, extended conformation. Protease-induced line-broadening studies helped identify the segments of inhibitors which come into contact with the protease. A comparison of the NMR data of the free and protease-bound states suggests that these ligands undergo rigidification upon complexation. This work provides the first structure of an inhibitor when bound to NS3 protease and should be valuable for designing more potent inhibitors.

NMR line-broadening and transferred NOESY as a medicinal chemistry tool for studying inhibitors of the hepatitis C virus NS3 protease domain

This work describes the use of NMR as a medicinal chemistry tool for better understanding the binding characteristics of inhibitors of the HCV NS3 protease. The protease-bound structure of a tetrapeptide-like inhibitor that has an acid C-terminus, a norvaline at P1 and a naphthylmethoxy proline at P2 is described. Conformational comparisons are made with a similar compound having a 1-amino-cyclopropylcarboxylic acid at P1 and with a hexapeptide inhibitor. Differences between the free and bound states are identified. 19F NMR also helped in determining that a single complex is observed when an inhibitor is added to the protease at a 1:1 ratio.

THE CONFORMATION OF A PEPTIDYL METHYL KETONE INHIBITOR BOUND TO THE HUMAN CYTOMEGALOVIRUS PROTEASE

A weak inhibitor means faster exchange! Since the methyl ketone MK2 is a weak noncovalent peptidyl inhibitor of the human cytomegalovirus protease, exchange between the free and enzyme-bound forms is rapid. This allows for the use of transferred NOE NMR methods and molecular modeling, which show that the bound conformation of MK2 is an extended peptide. This is confirmed by the results of an X-ray crystallographic analysis of a related enzyme-inhibitor complex.

Die Konformation eines an die humane Cytomegalievirus‐Protease gebundenen Peptidylmethylketon‐Inhibitors

Schwacher Inhibitor, schneller Austausch! Das Methylketon MK2 ist ein nur schwacher, nichtkovalent bindender Peptidyl-Inhibitor der humanen Cytomegalievirus-Protease, so das der Wechsel zwischen freier und enzymgebundener Form schnell erfolgt. Dies ermoglichte die Bestimmung der gebundenen Konformation von MK2 durch Transfer-NOE-NMR-Methoden und Molecular Modeling. Das Peptid bindet in einer gestreckten Konformation an die Protease, was anhand der Ergebnisse der Kristallstrukturanalyse eines verwandten Inhibitor-Enzym-Komplexes bestatigt wurde.

Influence of strain on hydrolysis of five-membered sulfate and phosphate esters

Relief of ring strain in the pentacoordinate state is supported by MO calculations as an explanation for rate enhancement in alkaline hydrolysis of five-membered sulfate diesters.