Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.16 (HIV-1 protease)
 2,107 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Patient human immunodeficiency virus type 1 (HIV-1) isolates that are resistant to protease inhibitors may contain amino acid substitutions L10I/V, M46L/I, G-48V, L63P, V82A/F/T, I84V, and L90M in the protease gene. Substitutions at positions 82 and/or 90 occur in variants that display high levels of resistance to certain protease inhibitors. Nucleotide substitutions at these two sites also lead to the loss of two HindII restriction enzyme digestion sites, and these changes make possible a rapid procedure for the detection of drug-resistant variants in patients on protease inhibitor therapy. This procedure was used to detect the emergence of mutated viruses at various times after the initiation of therapy with the HIV-1 protease inhibitor indinavir. The method includes viral RNA isolation from plasma and reverse transcription PCR amplification of the protease gene with fluorescence-tagged primers. The PCR product is digested with HindII, the cleavage products are separated on a urea-acrylamide gel in a DNA sequencer, and the extent of cleavage is automatically analyzed with commercially available software. In viruses from 34 blood samples from four patients, mutations leading to an amino acid change at residue 82 appeared as early as 6 weeks after the start of therapy and persisted throughout the course of the study period (48 weeks). Mutations leading to double substitutions at residues 82 and 90 were seen at a lower frequency and appeared later than the change at position 82. The changes detected by restriction enzyme cleavage were confirmed by DNA sequencing of the cloned protease genes by reverse transcription PCR amplification of viral RNA from isolates in plasma. In addition to the changes at positions 82 and 90, we have identified M46L/I, G48V, and I54V substitutions in isolates derived from indinavir-treated patients. HindII analysis of uncloned, PCR-amplified DNA offers a rapid screening procedure for the detection of virus isolates containing mutations at amino acid residues 82 and 90 in the HIV-1 protease gene. By using other restriction enzymes, the same method can be used to detect additional protease drug-resistant variants and is generally applicable for the detection of mutations.
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PMID:Emergence of protease inhibitor resistance mutations in human immunodeficiency virus type 1 isolates from patients and rapid screening procedure for their detection. 891 59

Cyclic urea amides, a novel series of HIV-1 protease (HIV PR) inhibitors, have increased activity against drug-resistant mutants of the HIV PR. The design strategy for these inhibitors is based on the hypotheses that (i) the hydrogen-bonding interactions between the inhibitor and the protease backbone will remain constant for wild-type and mutant enzymes and (ii) inhibitors which are capable of forming many nonbonded interactions, distributed throughout the active site, will experience a lower percent change in binding energy as a result of mutation in the target enzyme than those that form fewer interactions by partial occupation of the active site. The cyclic urea amide, SD146, forms 14 hydrogen bonds and 191 van der Waals contacts to HIV PR. SD146 is a very potent antiviral agent (IC90 = 5.1 nM) against wild-type HIV and maintains the same or improved level of high potency against a range of mutant strains of HIV with resistance to a wide variety of HIV protease inhibitors.
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PMID:Cyclic urea amides: HIV-1 protease inhibitors with low nanomolar potency against both wild type and protease inhibitor resistant mutants of HIV. 900 16

In cell cultures, the key residues associated with HIV-1 resistance to cyclic urea-based HIV-1 protease (PR) inhibitors are Val82 and Ile84 of HIV-1 PR. To gain an understanding of how these two residues modulate inhibitor binding, we have measured the Ki values of three recombinant mutant proteases, I84V, V82F, and V82F/I84V, for DMP323 and DMP450, and determined the three-dimensional structures of their complexes to 2.1-1.9 A resolution with R factors of 18.7-19.6%. The Ki values of these mutants increased by 25-, 0.5-, and 1000-fold compared to the wild-type values of 0.8 and 0.4 nM for DMP323 and DMP450, respectively. The wild-type and mutant complexes overall are very similar (rms deviations of 0.2-0.3 A) except for differences in the patterns of their van der Waals (vdw) interactions, which appear to modulate the Ki values of the mutants. The loss of the CD1 atom of Ile84, in the I84V mutant complexes, creates a hole in the S1 subsite, reducing the number of vdw contacts and increasing the Ki values. The V82F mutant binds DMP323 more tightly than wild type because the side chain of Phe82 forms additional vdw and edge-to-face interactions with the P1 group of DMP323. The Ki values of the single mutants are not additive because the side chain of Phe82 rotates out of the S1 subsite in the double mutant (the chi 1 angles of Phe82 and -182 in the V82F and V82F/I84V mutants differ by 90 and 185 degrees, respectively), further reducing the vdw interactions. Finally, compensatory shifts in the I84V and V82F/ I84V complexes pick up a small number of new contacts, but too few to offset the initial loss of interactions caused by the mutations. Therefore, our data suggest that variants persist in the presence of DMP323 and DMP450 because of a decrease in vdw interactions between the mutant proteases and inhibitors.
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PMID:Molecular basis of HIV-1 protease drug resistance: structural analysis of mutant proteases complexed with cyclic urea inhibitors. 904 41

Ten C2-symmetric cyclic urea and sulfamide derivatives have been synthesized from L-mannonic gamma-lactone and D-mannitol. The results of experimental measurement of their inhibitory potencies against HIV-1 protease were compared to calculated free energies of binding derived from molecular dynamics (MD) simulations. The compounds were selected, firstly, to enable elucidation of the role of stereochemistry for binding affinity (1a-d) and, secondly, to allow evaluation of the effects of variation in the link to the P1 and P1' phenyl groups on affinity (1a and 2-5). Thirdly, compounds with hydrogen bond-accepting or-donating groups attached to the phenyl groups in the P2 and P2' side chains (6 and 7) were selected. Binding free energies were estimated by a linear response method, whose predictive power for estimating binding affinities from MD simulations was demonstrated.
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PMID:Cyclic HIV-1 protease inhibitors derived from mannitol: synthesis, inhibitory potencies, and computational predictions of binding affinities. 908 77

Two cyclic, C2-symmetric HIV-1 protease inhibitors, one sulfamide and one urea derivative, both comprising phenyl ether groups in the P1/P1' positions, were cocrystallized with HIV-1 protease, and the crystal structures were determined to 2.0 A resolution. The structure of the urea 2 showed a conformation similar to that reported for the related urea 3 by Lam et al., while the sulfamide 1 adopted an unanticipated conformation in which the P1' and P2' side chains were transposed.
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PMID:Unexpected binding mode of a cyclic sulfamide HIV-1 protease inhibitor. 908 78

Comparison of the high-resolution X-ray structures of the native HIV-1 protease and its complexes with the inhibitors suggested that the enzyme flaps are flexible. The movement at the tip of the flaps could be as large as 7 A. On the basis of this observation, cyclic cyanoguanidines have been designed, synthesized, and evaluated as HIV-1 protease (PR) inhibitors. Cyclic cyanoguanidines were found to be very potent inhibitors of HIV-1 protease. The choice of cyclic cyanoguanidines over cyclic guanidines was based on the reduced basicity of the former. X-ray structure studies of the HIV PR complex with cyclic cyanoguanidine demonstrated that in analogy to cyclic urea, cyclic cyanoguanidines also displace the unique structural water molecule. The structure-activity relationship of the cyclic cyanoguanidines is compared with that of the corresponding cyclic urea analogues. The differences in binding constants of the two series of compounds have been rationalized using high-resolution X-ray structure information.
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PMID:Nonpeptide cyclic cyanoguanidines as HIV-1 protease inhibitors: synthesis, structure-activity relationships, and X-ray crystal structure studies. 955 78

As long as the threat of human immunodeficiency virus (HIV) protease drug resistance still exists, there will be a need for more potent antiretroviral agents. We have therefore determined the crystal structures of HIV-1 protease in complex with six cyclic urea inhibitors: XK216, XK263, DMP323, DMP450, XV638, and SD146, in an attempt to identify 1) the key interactions responsible for their high potency and 2) new interactions that might improve their therapeutic benefit. The structures reveal that the preorganized, C2 symmetric scaffolds of the inhibitors are anchored in the active site of the protease by six hydrogen bonds and that their P1 and P2 substituents participate in extensive van der Waals interactions and hydrogen bonds. Because all of our inhibitors possess benzyl groups at P1 and P1', their relative binding affinities are modulated by the extent of their P2 interactions, e.g. XK216, the least potent inhibitor (Ki (inhibition constant) = 4.70 nM), possesses the smallest P2 and the lowest number of P2-S2 interactions; whereas SD146, the most potent inhibitor (Ki = 0.02 nM), contains a benzimidazolylbenzamide at P2 and participates in fourteen hydrogen bonds and approximately 200 van der Waals interactions. This analysis identifies the strongest interactions between the protease and the inhibitors, suggests ways to improve potency by building into the S2 subsite, and reveals how conformational changes and unique features of the viral protease increase the binding affinity of HIV protease inhibitors.
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PMID:Molecular recognition of cyclic urea HIV-1 protease inhibitors. 957 85

A 3D-QSAR study using CoMFA methodology was conducted on a series of 29 symmetrical bis-benzamide cyclic urea derivatives having anti-HIV-1-protease activities. Active site minimization of the ligands was used to exclude conformations which are not sterically accessible within the active site. A significant cross validated correlation coefficient q2 (0.724) was obtained indicating the predictive potential of the model for untested compounds of this class. A significant non-cross-validated correlation coefficient (r2) of 0.971 with a low standard error estimate (S) of 0.119 was obtained indicating that the model reliably predicted the ant-protease activities of poorly to highly active compounds. The model was used to predict the anti-protease activities of eight test-set compounds, and the predicted values were in good agreement with the experimental values. The CoMFA coefficient contour plots identified several key features which explain the wide range of activities. The already reported 2D-QSAR along with the CoMFA model presented here may help in designing effective HIV-1 protease inhibitors.
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PMID:Comparative molecular field analysis (CoMFA) of a series of symmetrical bis-benzamide cyclic urea derivatives as HIV-1 protease inhibitors. 969 78

A quantitative structure-activity relationship (QSAR) study is described on some cyclic ureas that inhibit the enzyme HIV-1 protease (HIV-1-PR) and exhibit antiviral potency. Both the enzyme inhibition activity and the antiviral potency were found to be primarily governed by the hydrophobic property of the substituents at the nitrogens (N2/N2') of the urea. Adjacent to the nitrogens, the C1/C1'-substituents are, however, found to affect the activity (inhibition) by their molecular size. The essential binding of the ureas with the receptor is, however, through multiple hydrogen bonding, where the substituents, too, can participate in such binding if they are capable of doing so. A schematic diagram of the overall interaction of the inhibitors with the receptor is presented.
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PMID:Quantitative structure-activity relationship studies on cyclic urea-based HIV protease inhibitors. 982 4

We have synthesized stereoisomers of cyclic urea HIV-1 protease inhibitors to study the effect of varying configurations on binding affinities. Four different synthetic approaches were used to prepare the desired cyclic urea stereoisomers. The original cyclic urea synthesis using amino acid starting materials was used to prepare three isomers. Three additional isomers were prepared by synthetic routes utilizing L-tartaric acid and D-sorbitol as chiral starting materials. A stereoselective hydroxyl inversion of the cyclic urea trans-diol was used to prepare three additional isomers. In all 9 of the 10 possible cyclic urea stereoisomers were prepared, and their binding affinities are described.
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PMID:Stereoisomers of cyclic urea HIV-1 protease inhibitors: synthesis and binding affinities. 983 27


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