1.
Ahlsén, Göran, et al.
(författare)
Resistance profiles of cyclic and linear inhibitors of HIV-1 protease
2002
Ingår i: Antiviral Chemistry & Chemotherapy. - 0956-3202 .- 2040-2066. ; 13:1, s. 27-37
Tidskriftsartikel (refereegranskat) abstract
Resistance to anti-HIV protease drugs is a major problem in the design of AIDS drugs with long-term efficacy. To identify structural features associated with a certain resistance profile, the inhibitory properties of a series of symmetric and asymmetric cyclic sulfamide, cyclic urea and linear transition-state analogue inhibitors of HIV-1 protease were investigated using wild-type and mutant enzyme. To allow a detailed structure-inhibition analysis, enzyme with single, double, triple and quadruple combinations of G48V, V82A, 184V and L90M substitutions was used. Kinetic analysis of the mutants revealed that catalytic efficiency was 1-30% of that for the wild-type enzyme, a consequence of reduced kcat in all cases and an increased KM for all mutants except for the G48V enzyme. The overall structure-inhibitory profiles of the cyclic compounds were similar, and the inhibition of the V82A, 184V and G48V/L90M mutants were less efficient than of the wild-type enzyme. The greatest increase in Ki was generally observed for the 184V mutant and least for the G48V/L90M mutant, and additional combinations of mutations did not result in improved inhibition profiles for the cyclic compounds. An extended analysis of additional mutants, and including a set of linear compounds, showed that the profile was unique for each compound, and did not reveal any general structural features associated with a certain inhibition profile. The effects of structural modifications in the inhibitors, or of mutations, were not additive and they differed depending on their context. The results demonstrate the difficulties in predicting resistance, even for closely related compounds, and designing compounds with improved resistance profiles.
2.
Alterman, Mathias, et al.
(författare)
P1/P1' modified HIV protease inhibitors as tools in two new sensitive surface plasmon resonance biosensor screening assays
2001
Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier. - 0928-0987 .- 1879-0720. ; 13:2, s. 203-212
Tidskriftsartikel (refereegranskat) abstract
The commonly used HIV-1 protease assays rely on measurements of the effect of inhibitions on the hydrolysis rate of synthetic peptides. Recently an assay based on surface plasmon resonance (SPR) was introduced. We have taken advantage of the fact that the SPR signal is proportional to the mass of the analyte interacting with the immobilised molecule and developed two new improved efficient competition assay methods. Thus, high molecular weight binders were used as amplifiers of the surface plasmon resonance signal. Linkers were attached by a Heck reaction to the para-positions of the P1/P1′ benzyloxy groups of a linear C2-symmetric C-terminal duplicated inhibitor to enable (a) biotin labelling or (b) direct immobilisation of the inhibitor to the biosensor surface matrix. The interaction properties of a series of 17 structurally diverse inhibitors was assessed and compared to previously reported data. The most sensitive assay was obtained by immobilising the enzyme and amplifying the signal with an antibody, giving a detection range between 0.1 nM and 10 μM. Immobilisation of the inhibitor resulted in a stable and durable surface but a narrower detection range (1–100 nM). The two competition assays are anticipated to be very suitable for fast screening of potential HIV inhibitors.
3.
Hämäläinen, Markku D., et al.
(författare)
Characterization of a set of HIV-1 protease inhibitors using binding kinetics data from a biosensor-based screen
2000
Ingår i: Journal of Biomolecular Screening. - : Elsevier BV. - 1087-0571 .- 1552-454X. ; 5:5, s. 353-359
Tidskriftsartikel (refereegranskat) abstract
The interaction between 290 structurally diverse human immunodeficiency virus type 1 (HIV-1) protease inhibitors and the immobilized enzyme was analyzed with an optical biosensor, Although only a single concentration of inhibitor was used, information about the kinetics of the interaction could be obtained by extracting binding signals at discrete time points. The statistical correlation between the biosensor binding data, inhibition of enzyme activity (K-i), and viral replication (EC50) revealed that the association and dissociation rates for the interaction could be resolved and that they were characteristic for the compounds. The most potent inhibitors, with respect to K-i and EC50 values, including the clinically used drugs, all exhibited fast association and slow dissociation rates. Selective or partially selective binders for HIV-1 protease could be distinguished from compounds that showed a general protein-binding tendency by using three reference target proteins. This biosensor-based direct binding assay revealed a capacity to efficiently provide high-resolution information on the interaction kinetics and specificity of the interaction of a set of compounds with several targets simultaneously.
4.
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7.
Nurbo, Johanna, et al.
(författare)
β-Amino acid substitutions and structure-based CoMFA modeling of hepatitis C virus NS3 protease inhibitors
2008
Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 16:10, s. 5590-5605
Tidskriftsartikel (refereegranskat) abstract
In an effort to develop a new type of HCV NS3 peptidomimetic inhibitor, a series of tripeptide inhibitors incorporating a mix of alpha- and beta-amino acids has been synthesized. To understand the structural implications of beta-amino acid substitution, the P(1), P(2), and P(3) positions of a potent tripeptide scaffold were scanned and combined with carboxylic acid and acyl sulfonamide C-terminal groups. Inhibition was evaluated and revealed that the structural changes resulted in a loss in potency compared with the alpha-peptide analogues. However, several compounds exhibited muM potency. Inhibition data were compared with modeled ligand-protein binding poses to understand how changes in ligand structure affected inhibition potency. The P(3) position seemed to be the least sensitive position for beta-amino acid substitution. Moreover, the importance of a proper oxyanion hole interaction for good potency was suggested by both inhibition data and molecular modeling. To gain further insight into the structural requirements for potent inhibitors, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model has been constructed using comparative molecular field analysis (CoMFA). The most predictive CoMFA model has q(2)=0.48 and r(pred)(2)=0.68.
8.
9.
Poliakov, Anton, et al.
(författare)
Mechanistic studies of electrophilic protease inhibitors of full length hepatic C virus (HCV) NS3
2007
Ingår i: Journal of enzyme inhibition and medicinal chemistry (Print). - : Informa UK Limited. - 1475-6366 .- 1475-6374. ; 22:2, s. 191-199
Tidskriftsartikel (refereegranskat) abstract
The inhibition mechanism of electrophilic peptide-based protease inhibitors of full-length hepatitis C virus (HCV) NS3 has been investigated by determining the Ki-values for a series of compounds differing in the electrophilicity and acidity of the C-terminal residue at pH-values above and below the pKa of the catalytic histidine (6.85) and at two different ionic strengths. Electrophilic compounds with a pentafluoroethyl ketone group showed stronger inhibition at pH 8 than pH 6, as expected for a mechanism requiring an unprotonated catalytic histidine. However, the difference was only significant at high ionic strength. In contrast, electrophilic compounds with an acidic C-terminal group or a cyclic P1 residue showed a lower inhibitory effect at pH 8 than at pH 6, inconsistent with a mechanism-based inhibition. Moreover, all electrophilic compounds had an unexpectedly strong inhibition at pH 6, when mechanism-based inhibition is unlikely. The results suggest that for some of the electrophilic compounds the reactive group may not be properly positioned in the active site and that binding of these inhibitors is a result of non-covalent interactions. The nature of these interactions is discussed.
10.
Rönn, Robert, et al.
(författare)
Evaluation of a diverse set of potential P1 carboxylic acid bioisosteres in hepatitis C virus NS3 protease inhibitors
2007
Ingår i: Bioorganic & Medicinal Chemistry. - : Elsevier BV. - 0968-0896 .- 1464-3391. ; 15:12, s. 4057-4068
Tidskriftsartikel (refereegranskat) abstract
There is an urgent need for more efficient therapies for people infected with hepatitis C virus (HCV). HCV NS3 protease inhibitors have shown proof-of-concept in clinical trials, which make the virally encoded NS3 protease an attractive drug target. Product-based NS3 protease inhibitors comprising a P1 C-terminal carboxylic acid have shown to be effective and we were interested in finding alternatives to this crucial carboxylic acid group. Thus, a series of diverse P1 functional groups with different acidity and with possibilities to form a similar, or an even more powerful, hydrogen bond network as compared to the carboxylic acid were synthesized and incorporated into potential inhibitors of the NS3 protease. Biochemical evaluation of the inhibitors was performed in both enzyme and cell-based assays. Several non-acidic C-terminal groups, such as amides and hydrazides, were evaluated but failed to produce inhibitors more potent than the corresponding carboxylic acid inhibitor. The tetrazole moiety, although of similar acidity to a carboxylic acid, provided an inhibitor with mediocre potencies in both assays. However, the acyl cyanamide and the acyl sulfinamide groups rendered compounds with low nanomolar inhibitory potencies and were more potent than the corresponding carboxylic acid inhibitor in the enzymatic assay. Additionally, results from a pH-study suggest that the P1 C-terminal of the inhibitors comprising a carboxylic acid, an acyl sulfonamide or an acyl cyanamide group binds in a similar mode in the active site of the NS3 protease.
