Multiple copy simultaneous search and construction of ligands in binding sites: application to inhibitors of HIV-1 aspartic proteinase (original) (raw)
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Design of new inhibitors of HIV-1 aspartic protease
We present an approach for designing new inhibitors (I) of HIV-1 aspartic protease (PR) based on calculation of relative binding energies, taking into account contributions from all species involved in the complexation equilibrium (I + PR * I:PR), as well as their solvation. This allows a rational design of new structures with predicted enhanced inhibitory potency. We have also analysed the role in binding affinity of the central non-scissile bond (X1-X2) as well as of flanking amino acid residues Pn of inhibitor structures (P3-P2-Pl -Xl -X2-P l'-P2'-P3'). 0301-0104/96/$15.00 0 1996 Elsevier Science B.V. All rights reserved SSDI 0301-0104(95)00363-O
Molecular BioSystems, 2012
Acquired immunodeficiency syndrome (AIDS) is a dangerous disease, which damages the immune system cells to the point that the immune system can no longer fight against other infections that it would usually be able to prevent. The causal agent is the human immunodeficiency virus (HIV), and for this reason, the search for more effective chemotherapies against HIV is a challenge for the scientific community. Chemoinformatics and Quantitative Structure-Activity Relationship (QSAR) studies have played an essential role in the design of potent inhibitors for proteins associated with the HIV infection. However, all previous studies took into consideration the discovery of future drug candidates using homogeneous series of compounds against only one protein. This fact limits the use of more efficient anti-HIV chemotherapies. In this work, we develop the first ligand-based approach for the in silico design of multi-target (mt) inhibitors for seven key proteins associated with the HIV infection. Two mt-QSAR models were constructed from a large and heterogeneous database of compounds. The first model was based on linear discriminant analysis (mt-QSAR-LDA) employing fragment-based descriptors. The second model was obtained using artificial neural networks (mt-QSAR-ANN) with global 2D descriptors. Both models correctly classified more than 90% of active and inactive compounds in training and prediction sets. Some fragments were extracted and their contributions to anti-HIV activity through inhibition of the different proteins were calculated using the mt-QSAR-LDA model. New molecules designed from fragments with positive contributions were suggested and correctly predicted by the two models as possible potent and versatile anti-HIV agents.
Proceedings of the National Academy of Sciences, 2006
HIV-1 protease is an effective target for designing drugs against AIDS, and structural information about the true transition state and the correct mechanism can provide important inputs. We present here the three-dimensional structure of a bi-product complex between HIV-1 protease and the two cleavage product peptides AETF and YVDGAA. The structure, refined against synchrotron data to 1.65 Å resolution, shows the occurrence of the cleavage reaction in the crystal, with the product peptides still held in the enzyme active site. The separation between the scissile carbon and nitrogen atoms is 2.67 Å, which is shorter than a normal van der Waal separation, but it is much longer than a peptide bond length. The substrate is thus in a stage just past the G'Z intermediate described in Northrop's mechanism [Northrop DB (2001) Acc Chem Res 34:790-797]. Because the products are generated in situ, the structure, by extrapolation, can give insight into the mechanism of the cleavage reaction. Both oxygens of the generated carboxyl group form hydrogen bonds with atoms at the catalytic center: one to the OD2 atom of a catalytic aspartate and the other to the scissile nitrogen atom. The latter hydrogen bond may have mediated protonation of scissile nitrogen, triggering peptide bond cleavage. The inner oxygen atoms of the catalytic aspartates in the complex are 2.30 Å apart, indicating a low-barrier hydrogen bond between them at this stage of the reaction, an observation not included in Northrop's proposal. This structure forms a template for designing mechanism-based inhibitors.
Structure Based Design of Inhibitors of Aspartic Protease of HIV-1
Letters in Drug Design & Discovery, 2005
The aspartic protease of HIV-1 represents a valid therapeutic target of antiviral agents suitable for the treatment of AIDS. We have designed peptidomimetic inhibitors for this enzyme with a hydroxyethylenediamine core, based on a molecular modeling approach that predicts the effectiveness of the designed compounds in terms of computed enzyme-inhibitor complexation Gibbs free energies. This structurebased molecular design was then combined with a synthetic strategy that couples stereochemical control with full flexibility in the choice of the central core side chains and of the flanking residues. A series of peptidomimetic inhibitors was thus assembled from readily available amino acids and carboxylic acids and -Phe-ψ[CH 2 -(r/s)CHOH]-Phe-cores. The IC 50 values for these compounds ranged from 3 nM to 80 µM , allowing a QSAR analysis and identification of factors that determine the inhibition potency of the compounds. Predicted ADME-related properties of the inhibitor candidates span a range of pharmacokinetics profiles, which allows selection of a potent and bioavailable lead compound for further development.
Proteins, 2008
Drug resistance in HIV-1 protease, a barrier to effective treatment, is generally caused by mutations in the enzyme that disrupt inhibitor binding but still allow for substrate processing. Structural studies with mutant, inactive enzyme, have provided detailed information regarding how the substrates bind to the protease yet avoid resistance mutations; insights obtained inform the development of next generation therapeutics. Although structures have been obtained of complexes between substrate peptide and inactivated (D25N) protease, thermodynamic studies of peptide binding have been challenging due to low affinity. Peptides that bind tighter to the inactivated protease than the natural substrates would be valuable for thermodynamic studies as well as to explore whether the structural envelope observed for substrate peptides is a function of weak binding. Here, two computational methods-namely, charge optimization and protein design-were applied to identify peptide sequences predict...
Biopolymers, 2007
HIV-1 protease (HIV-1 PR), which is encoded by retroviruses, is required for the processing of gag and pol polyprotein precursors, hence it is essential for the production of infectious viral particles. In vitro inhibition of the enzyme results in the production of progeny virions that are immature and noninfectious, suggesting its potential as a therapeutic target for AIDS. Although a number of potent protease inhibitor drugs are now available, the onset of resistance to these agents due to mutations in HIV-1 PR has created an urgent need for new means of HIV-1 PR inhibition. Whereas enzymes are usually inactivated by blocking of the active site, the structure of dimeric HIV-1 PR allows an alternative inhibitory mechanism. Since the active site is formed by two half-enzymes, which are connected by a fourstranded antiparallel b-sheet involving the N-and Ctermini of both monomers, enzyme activity can be abolished by reagents targeting the dimer interface in a region relatively free of mutations would interfere with formation or stability of the functional HIV-1 PR dimer.
Proceedings / ... International Conference on Intelligent Systems for Molecular Biology ; ISMB. International Conference on Intelligent Systems for Molecular Biology, 1999
Screening for potential ligands and docking them into the binding sites of proteins is one of the main tasks in computer-aided drug design. Despite the progress in computational power, it remains infeasible to model all the factors involved in molecular recognition, especially when screening databases of more than 100,000 compounds. While ligand flexibility is considered in most approaches, the model of the binding site is rather simplistic, with neither solvation nor induced complementary usually taken into consideration. We present results for screening different databases for HIV-1 protease ligands with our tool Slide, and investigate the extent to which binding-site conformation, solvation, and template representation generate bias. The results suggest a strategy for selecting the optimal binding-site conformation, for cases in which more than one independent structure is available, and selecting a representation of that binding site that yields reproducible results and the iden...
The Journal of biological chemistry, 1993
A stable, non-peptide inhibitor of the protease from type 1 human immunodeficiency virus has been developed, and the stereochemistry of binding defined through crystallographic three-dimensional structure determination. The initial compound, haloperidol, was discovered through computational screening of the Cambridge Structural Database using a shape complementarity algorithm. The subsequent modification is a non-peptidic lateral lead, which belongs to a family of compounds with well characterized pharmacological properties. This thioketal derivative of haloperidol and a halide counterion are bound within the enzyme active site in a mode distinct from the observed for peptide-based inhibitors. A variant of the protease cocrystallized with this inhibitor shows binding in the manner predicted during the initial computer-based search. The structures provide the context for subsequent synthetic modifications of the inhibitor.