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Meng J, Lai MT, Munshi V, Grobler J, McCauley J, Zuck P, Johnson EN, Uebele VN, Hermes JD, Adam GC. Screening of HIV-1 Protease Using a Combination of an Ultra-High-Throughput Fluorescent-Based Assay and RapidFire Mass Spectrometry. ACTA ACUST UNITED AC 2015; 20:606-15. [PMID: 25681434 DOI: 10.1177/1087057115570838] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/12/2015] [Indexed: 12/19/2022]
Abstract
HIV-1 protease (PR) represents one of the primary targets for developing antiviral agents for the treatment of HIV-infected patients. To identify novel PR inhibitors, a label-free, high-throughput mass spectrometry (HTMS) assay was developed using the RapidFire platform and applied as an orthogonal assay to confirm hits identified in a fluorescence resonance energy transfer (FRET)-based primary screen of > 1 million compounds. For substrate selection, a panel of peptide substrates derived from natural processing sites for PR was evaluated on the RapidFire platform. As a result, KVSLNFPIL, a new substrate measured to have a ~ 20- and 60-fold improvement in k cat/K m over the frequently used sequences SQNYPIVQ and SQNYPIV, respectively, was identified for the HTMS screen. About 17% of hits from the FRET-based primary screen were confirmed in the HTMS confirmatory assay including all 304 known PR inhibitors in the set, demonstrating that the HTMS assay is effective at triaging false-positives while capturing true hits. Hence, with a sampling rate of ~7 s per well, the RapidFire HTMS assay enables the high-throughput evaluation of peptide substrates and functions as an efficient tool for hits triage in the discovery of novel PR inhibitors.
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Affiliation(s)
- Juncai Meng
- Screening and Protein Sciences, Merck Research Labs, North Wales, PA, USA
| | - Ming-Tain Lai
- Department of Infectious Disease, Merck Research Labs, West Point, PA, USA
| | - Vandna Munshi
- Department of Infectious Disease, Merck Research Labs, West Point, PA, USA
| | - Jay Grobler
- Department of Infectious Disease, Merck Research Labs, West Point, PA, USA
| | - John McCauley
- Medicinal Chemistry, Merck Research Labs, West Point, PA, USA
| | - Paul Zuck
- Screening and Protein Sciences, Merck Research Labs, North Wales, PA, USA
| | - Eric N Johnson
- Screening and Protein Sciences, Merck Research Labs, North Wales, PA, USA Wuxi Apptech
| | - Victor N Uebele
- Screening and Protein Sciences, Merck Research Labs, North Wales, PA, USA
| | - Jeffrey D Hermes
- Screening and Protein Sciences, Merck Research Labs, North Wales, PA, USA
| | - Gregory C Adam
- Screening and Protein Sciences, Merck Research Labs, North Wales, PA, USA
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A drug discovery platform: a simplified immunoassay for analyzing HIV protease activity. J Virol Methods 2012; 186:21-9. [PMID: 22846787 DOI: 10.1016/j.jviromet.2012.07.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 07/17/2012] [Accepted: 07/18/2012] [Indexed: 01/09/2023]
Abstract
Although numerous methods for the determination of HIV protease (HIV-PR) activity have been described, new high-throughput assays are required for clinical and pharmaceutical applications due to the occurrence of resistant strains. In this study, a simple enzymatic immunoassay to identify HIV-PR activity was developed based on a Ni(2+)-immobilized His(6)-Matrix-Capsid substrate (H(6)MA-CA) is cleaved by HIV protease-His(6) (HIV-PRH(6)) which removes the CA domain and exposes the free C terminus of MA. Following this cleavage, two monoclonal antibodies specific for either the free C-terminal MA or CA epitope are used to quantify the proteolytic activity using a standard ELISA-based system. Specificity for detection of the HIV-PRH(6) activity was confirmed with addition of protease inhibitor (PI), lopinavir. In addition, the assay was able to detect an HIV-PR variant activity indicating that this assay is capable of assessing viral mutation affect HIV-PR activity. The efficacy of commercially available PIs and their 50% inhibitory concentration (IC(50)) were determined. This assay provides a high-throughput method for both validating the efficiency of new drugs in vitro and facilitating the discovery of new PIs. In addition, it could serve as a method for examining the influence of various mutations in HIV-PRs isolated from drug-resistant strains.
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Functional protease assay using liquid crystals as a signal reporter. Biosens Bioelectron 2012; 35:174-179. [DOI: 10.1016/j.bios.2012.02.042] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/18/2012] [Accepted: 02/20/2012] [Indexed: 11/22/2022]
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Askin SP, Morin I, Schaeffer PM. Development of a protease activity assay using heat-sensitive Tus-GFP fusion protein substrates. Anal Biochem 2011; 415:126-33. [PMID: 21570945 DOI: 10.1016/j.ab.2011.04.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2011] [Revised: 04/19/2011] [Accepted: 04/19/2011] [Indexed: 11/28/2022]
Abstract
Proteases are implicated in various diseases and several have been identified as potential drug targets or biomarkers. As a result, protease activity assays that can be performed in high throughput are essential for the screening of inhibitors in drug discovery programs. Here we describe the development of a simple, general method for the characterization of protease activity and its use for inhibitor screening. GFP was genetically fused to a comparatively unstable Tus protein through an interdomain linker containing a specially designed protease site, which can be proteolyzed. When this Tus-GFP fusion protein substrate is proteolyzed it releases GFP, which remains in solution after a short heat denaturation and centrifugation step used to eliminate uncleaved Tus-GFP. Thus, the increase in GFP fluorescence is directly proportional to protease activity. We validated the protease activity assay with three different proteases, i.e., trypsin, caspase 3, and neutrophil elastase, and demonstrated that it can be used to determine protease activity and the effect of inhibitors with small sample volumes in just a few simple steps using a fluorescence plate reader.
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Affiliation(s)
- Samuel P Askin
- Comparative Genomics Centre, School of Pharmacy and Molecular Sciences, James Cook University, DB 21, James Cook Drive, Townsville, QLD 4811, Australia
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Selective and facile assay of human immunodeficiency virus protease activity by a novel fluorogenic reaction. Anal Biochem 2009; 397:197-201. [PMID: 19852926 PMCID: PMC7094380 DOI: 10.1016/j.ab.2009.10.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 10/07/2009] [Accepted: 10/16/2009] [Indexed: 02/06/2023]
Abstract
A highly selective and facile assay of human immunodeficiency virus protease (HIV-PR) has been required for the screening of medicinal inhibitors and also for classifying the subtypes of HIV in the therapeutic treatment of acquired immune deficiency syndrome (AIDS). This article describes a novel assay method of HIV-PR based on the selective fluorogenic reaction of peptides. A peptide fragment generated from a substrate by the enzymatic digestion with HIV-PR could be selectively quantified by the spectrofluorometric detection after the fluorogenic reaction with catechol in the presence of sodium periodate and sodium borate (pH 7.0). This assay system uses an N-terminal acetyl peptide as the substrate and crude extracts from Escherichia coli expressing recombinant HIV-PR. The activity obtained by the proposed assay correlated with that obtained by a conventional HIV-PR assay based on fluorescence resonance energy transfer detection.
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Horáková D, Rumlová M, Pichová I, Ruml T. Luminometric method for screening retroviral protease inhibitors. Anal Biochem 2005; 345:96-101. [PMID: 16125122 DOI: 10.1016/j.ab.2005.07.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Revised: 06/30/2005] [Accepted: 07/12/2005] [Indexed: 01/08/2023]
Abstract
We have developed a sensitive luminometric assay for determining the activity of retroviral proteases that uses proteolytic cleavage of polypeptide substrate immobilized on Ni-NTA HisSorb Strips microplates. The protease substrate derived from the Gag precursor protein of Mason-Pfizer monkey virus (M-PMV) was conjugated with horseradish peroxidase (HRP), which catalyzes oxidation of luminol in the assay. The cleavage of the substrate was monitored as a decrease in luminescent signal caused by the release of the cleavage product conjugated to HRP. Testing of a set of M-PMV protease inhibitors confirmed that this method is sufficiently sensitive and specific for high-throughput screening of retroviral protease inhibitors.
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Affiliation(s)
- Dana Horáková
- Department of Biochemistry and Microbiology, Institute of Chemical Technology, Technická 3, 166 28 Prague, Czech Republic
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Sperka T, Pitlik J, Bagossi P, Tözsér J. Beta-lactam compounds as apparently uncompetitive inhibitors of HIV-1 protease. Bioorg Med Chem Lett 2005; 15:3086-90. [PMID: 15893929 DOI: 10.1016/j.bmcl.2005.04.020] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Revised: 03/31/2005] [Accepted: 04/14/2005] [Indexed: 10/25/2022]
Abstract
Compounds of a combinatorial monocyclic beta-lactam library were found to be apparently uncompetitive inhibitors of HIV-1 protease, providing lead compounds for a new class of HIV protease inhibitors.
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Affiliation(s)
- Tamás Sperka
- Department of Biochemistry and Molecular Biology, Research Center for Molecular Medicine, University of Debrecen, Faculty of Medicine, H-4012 Debrecen, Hungary
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Gutiérrez OA, Salas E, Hernández Y, Lissi EA, Castrillo G, Reyes O, Garay H, Aguilar A, García B, Otero A, Chavez MA, Duarte CA. An immunoenzymatic solid-phase assay for quantitative determination of HIV-1 protease activity. Anal Biochem 2002; 307:18-24. [PMID: 12137774 DOI: 10.1016/s0003-2697(02)00009-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A novel immunoenzymatic procedure for the quantitative determination of HIV protease activity is provided. An N-terminal biotinylated peptide (DU1) that comprises an HIV-1 protease (HIV-PR) cleavage sequence was bound to streptavidin-coated microtiter plates. The bound peptide can be quantified by an immunoenzymatic procedure (enzyme-linked immunosorbent assay, ELISA) that includes a monoclonal antibody (Mab 332) against the peptide (DU1) C-terminal. The incubation of the bound peptide with HIV-PR in solution resulted in a signal decrement, as the peptide was hydrolyzed and the released C-terminal segment washed away. An equation that relates the amount of added enzyme to the kinetics of the reaction was written in order to describe this heterogeneous enzyme-quasi-saturable system. This equation allows quantitative determination of protease activity, a feature widely underrated in previous similar assays. The assay also allows evaluation of the inhibitory activity of HIV-PR inhibitors. Due to the intrinsic advantages of the ELISA format, this method could be used in high-throughput screening of HIV protease inhibitors. The assay can be extended to other proteolytic enzymes.
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Affiliation(s)
- Omar A Gutiérrez
- Facultad de Biología, Centro de Estudios de la Proteínas, Universidad de la Habana, Ciudad Habana, Cuba.
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Lindsten K, Uhlíková T, Konvalinka J, Masucci MG, Dantuma NP. Cell-based fluorescence assay for human immunodeficiency virus type 1 protease activity. Antimicrob Agents Chemother 2001; 45:2616-22. [PMID: 11502538 PMCID: PMC90701 DOI: 10.1128/aac.45.9.2616-2622.2001] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) protease is essential for production of infectious virus and is therefore a major target for the development of drugs against AIDS. Cellular proteins are also cleaved by the protease, which explains its cytotoxic activity and the consequent failure to establish convenient cell-based protease assays. We have exploited this toxicity to develop a new protease assay that relies on transient expression of an artificial protease precursor harboring the green fluorescent protein (GFP-PR). The precursor is activated in vivo by autocatalytic cleavage, resulting in rapid elimination of protease-expressing cells. Treatment with therapeutic doses of HIV-1 protease inhibitors results in a dose-dependent accumulation of the fluorescent precursor that can be easily detected and quantified by flow cytometric and fluorimetric assays. The precursor provides a convenient and noninfectious model for high-throughput screenings of substances that can interfere with the activity of the protease in living cells.
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Affiliation(s)
- K Lindsten
- Microbiology and Tumor Biology Center, Karolinska Institutet, S-171 77 Stockholm, Sweden
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