Nancy Butkiewicz

Structure of Sch 68631: A new hepatitis C virus proteinase inhibitor from Streptomyces sp.

Abstract A novel hepatitis C virus (HCV) proteinase inhibitor, Sch 68631 ( 1 ), was isolated from the fermentation culture broth of Streptomyces sp. The structure of 1 was elucidated by analyses of spectroscopic data and shown to be a new member of the phenanthrenequinone family of compounds.

Amantadine and Rimantadine Have No Direct Inhibitory Effects against Hepatitis C Viral Protease, Helicase, ATPase, Polymerase, and Internal Ribosomal Entry Site-Mediated Translation

Amantadine, a drug known to inhibit influenza A viral matrix (M2) protein function, was reported to be an effective treatment in some patients with chronic hepatitis C virus (HCV) infection. Sequence comparison shows no homology between M2 and any of the HCV proteins. The effects of amantadine and a related analogue, rimantadine, on viral protease, helicase, ATPase, RNA-dependent RNA polymerase, and HCV internal ribosomal entry site (IRES) translation were tested by established in vitro biochemical assays. No inhibition (>15%) of HCV protease, helicase, ATPase, and polymerase was observed with concentrations up to 400 microgram/mL. IRES-specific inhibition was not observed at clinically relevant concentrations, but both cap and IRES reporter genes were suppressed at higher levels, suggesting nonspecific translation inhibition. In conclusion, amantadine and rimantadine have no direct and specific inhibitory effects against HCV protease, helicase, ATPase, polymerase, and IRES in vitro.

Isolation and structure of SCH 351633 : A novel hepatitis C virus (HCV) NS3 protease inhibitor from the fungus Penicillium griseofulvum

A new hepatitis C virus (HCV) protease inhibitor designated as Sch 351633 (1) was isolated from the fungus, Penicillium griseofulvum. Structure elucidation of 1 was accomplished by analysis of spectroscopic data, which determined compound 1 to be a bicyclic hemiketal lactone. Compound 1 exhibited inhibitory activity in the HCV protease assay with an IC50 value of 3.8 microg/mL.

Two antiviral compounds from the plant Stylogne cauliflora as inhibitors of HCV NS3 protease

The 70% aq methanolic extract of the Peruvian plant Stylogne cauliflora was found to contain two novel oligophenolic compounds SCH 644343 (1) and SCH 644342 (2), which were identified as inhibitors of HCV NS3 protease. The structure of 1 and 2 was established based on high-resolution NMR studies. Compound 1 inhibited HCV NS3 protease with an IC(50) of 0.3 microM, while compound 2 showed an IC(50) of 0.8 microM.

Cross-genotypic interaction between hepatitis C virus NS3 protease domains and NS4A cofactors

BACKGROUND/AIMS Hepatitis C virus (HCV) nonstructural protein 3 (NS3) protease requires NS4A as a cofactor. This cofactor activity has been mapped to the central region of NS4A which interacts with the N-terminus of NS3 protease. To investigate whether this interaction is conserved among different genotypes of HCV cross-genotypic characterization were performed to delineate the importance of NS4A cofactor function in relation to the molecular evolution of HCV METHODS: Active NS3 protease domains of genotype 1-3 (representing five subtypes: la, 1b, 2a, 2b and 3a) were produced and purified from bacterial cells. NS4A cofactor-dependent in vitro trans cleavage assays were established using the in vitro translated recombinant protein substrates. These substrates contained the junction site of NS4A/NS4B, NS4B/NS5A or NS5A/NS5B. RESULTS Our data revealed that NS3 proteases cross-interacted with NS4A cofactors derived from different genotypes, although the genotype 2 cofactor was less efficient, which could be due to greater genetic variations in this region. Furthermore, the corresponding region in hepatitis G virus (HGV) NS4A was found to provide weak cofactor activity for HCV NS3 protease. Surprisingly, a synthetic substrate peptide from the NS4B/NS5A junction was also found to enhance HCV NS3 protease activity in a dose-dependent manner. CONCLUSION Our study suggests that the NS4A cofactor function is well conserved among HCV It is likely that other HCV-related viruses may have developed similar strategies to regulate their protease activity.

The synthesis of novel HIV-protease inhibitors

The syntheses, enzyme inhibition and antiviral activity of potent HIV-protease inhibitors containing novel beta-hydroxy ether and thioethers based on the transition state mimetic concept are discussed.

Novel HIV- protease inhibitors containing β-hydroxyether and -thioether dipeptide isostere surrogates: modification of the P3 ligand

Studies involving modifications to the P3 position of previously described HIV-protease inhibitors containing beta-hydroxyether and thioether dipeptide isostere replacements led to the discovery of pseudopeptides 8o and 8p with improved antiviral activities.

Inactivation of the human cytomegalovirus protease by diisopropylfluorophosphate

Publisher Summary Cytomegalovirus (CMV) protease is a serine protease, and labeling with diisopropylfluorophosphate (DFP) has identified Ser132 as the active site serine. The structure of the CMV protease containing the diisopropylphosphorylserine at residue 132 (DIP-CMV protease) is likely to resemble that of the tetrahedral transition-state intermediate. As the structure of the DFP-treated serine proteases resembles that of the tetrahedral transition-state intermediate, and the inactivated enzyme would not be susceptible to autoproteolysis, production of DIP-CMV protease would be useful for structure based drug design. The concentrations of DFP sufficient to yield stoichiometric incorporation of inhibitor at the active site of CMV protease, also resulted in substantial incorporation of DIP at a second site or sites. This heterogeneous incorporation would preclude crystallographic studies. For this reason, this chapter has attempted to optimize the conditions for inactivation of CMV protease with DFP, to produce pure DIP-CMV protease with minimum second site incorporation. Initial studies indicated that there was no loss of protease activity in the control samples, even when incubated for 23 hours at 22°C. A 3.8 hour incubation was sufficient to completely inactivate 180 μM protease in the presence of 4.3 mM DFP, while a 2.4 fold excess of the inhibitor inactivated only 50% of the enzyme. This indicates that CMV protease is less reactive with DFP than trypsin or chymotrypsin, and requires an order of magnitude excess of the organophosphate to achieve complete inactivation.