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Open AccessJournal ArticleDOI

IC50-to-Ki: a web-based tool for converting IC50 to Ki values for inhibitors of enzyme activity and ligand binding

TLDR
A new web-server tool estimates Ki values from experimentally determined IC50 values for inhibitors of enzymes and of binding reactions between macromolecules and ligands to enable end users to help gauge the quality of the underlying assumptions used in these calculations.
Abstract
A new web-server tool estimates Ki values from experimentally determined IC50 values for inhibitors of enzymes and of binding reactions between macromolecules (e.g. proteins, polynucleic acids) and ligands. This converter was developed to enable end users to help gauge the quality of the underlying assumptions used in these calculations which depend on the type of mechanism of inhibitor action and the concentrations of the interacting molecular species. Additional calculations are performed for nonclassical, tightly bound inhibitors of enzyme-substrate or of macromolecule-ligand systems in which free, rather than total concentrations of the reacting species are required. Required userdefined input values include the total enzyme (or another target molecule) and substrate (or ligand) concentrations, the Km of the enzyme-substrate (or the Kd of the target-ligand) reaction, and the IC50 value. Assumptions and caveats for these calculations are discussed along with examples taken from the literature. The host database for this converter contains kinetic constants and other data for inhibitors of the proteolytic clostridial neurotoxins (http:// botdb.abcc.ncifcrf.gov/toxin/kiConverter.jsp).

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Design and evaluation of novel piperidine HIV-1 protease inhibitors with potency against DRV-resistant variants

TL;DR: In this article, a novel class of HIV-1 protease inhibitors with flexible piperidine as the P2 ligand was designed with the aim of improving extensive interactions with the active subsites.
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Inhibition of human UDP-glucuronosyltransferase enzymes by midostaurin and ruxolitinib: implications for drug-drug interactions.

TL;DR: It is found that midostaurin is a potent inhibitor of the majority of human UGTs and may bring a potential risk of DDI via inhibition against UGT1A3, 1A7, and 1A8, while ruxolitinib cannot trigger UGT‐mediated DDI due to its weak inhibition towards U GTs.
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Chemical structure and correlation analysis of HIV-1 NNRT and NRT inhibitors and database-curated, published inhibition constants with chemical structure in diverse datasets

TL;DR: For both subsets, descriptive and predictive QSAR models are derived, discussed and externally validated, revealing general trends in relationships between molecular structure and binding affinity constants in structurally diverse datasets.
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Modulation of Glycine Receptor-Mediated Pain Signaling in vitro and in vivo by Glucose

TL;DR: Glucose showed mild analgesic effects and was able to compensate for strychnine-induced allodynia in mice and suggest a molecular mechanism for glucose-mediated analgesia.
References
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Journal ArticleDOI

Relationship between the inhibition constant (K1) and the concentration of inhibitor which causes 50 per cent inhibition (I50) of an enzymatic reaction.

TL;DR: The analysis described shows K I does not equal I 50 when competitive inhibition kinetics apply; however, K I is equal to I 50 under conditions of either noncompetitive or uncompetitive kinetics.
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Development and optimization of a binding assay for the XIAP BIR3 domain using fluorescence polarization

TL;DR: The development of a homogeneous high-throughput assay based on fluorescence polarization for measuring the binding affinities of small-molecule inhibitors to the BIR3 domain of XIAP and results obtained indicated that the FP-based competitive binding assay performs correctly as designed.
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A linear equation that describes the steady-state kinetics of enzymes and subcellular particles interacting with tightly bound inhibitors.

TL;DR: D dose-response measurements generate a linear plot of inhibitor concentration divided by degree of inhibition against velocity without inhibitor divided by velocity with inhibitor, which indicates that the inhibitors of oxidative phosphorylation, rutamycin and bongkrekic acid, are tightly bound to rat liver mitochondria.
Journal ArticleDOI

BRENDA, AMENDA and FRENDA the enzyme information system: new content and tools in 2009

TL;DR: The web service via a SOAP (Simple Object Access Protocol) interface for access to the BRENDA data has been further enhanced and a new search option provides the access to protein-specific data.
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Fluorescence Polarization Competition Assay: The Range of Resolvable Inhibitor Potency Is Limited by the Affinity of the Fluorescent Ligand

TL;DR: The higher the affinity of the fluorescent ligand, the wider the range of inhibitor potency that can be resolved, and an approximate estimate for the low end of inhibitor K(i) values thatCan be resolved is the K(d) value of theorescent ligand.
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