title: Rapid Determination of the Specificity Constant of Irreversible Inhibitors (kinact/KI) by Means of an Endpoint Competition Assay.
abstract: Owing to their covalent target occupancy, irreversible inhibitors require low exposures and offer long duration, and their use thus represents a powerful strategy for achieving pharmacological efficacy. Importantly, the potency metric of irreversible inhibitors is kinact/KI not IC50. A simple approach to measuring kinact/KI was developed that makes use of an irreversible probe for competitive assays run to completion against test compounds. In this system, the kinact/KI value of the test compound is equal to (kinact/KI)probe ×[probe]/IC50. The advantages of this method include simplicity, high throughput, and application to all target classes, and it only requires an in-depth kinetic evaluation of the probe.
authors.affiliation: Biomolecular Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Ltd., 26-1, Muraoka-higashi 2-chome, Fujisawa, Kanagawa 251-8555 (Japan). ikuo.miyahisa@takeda.com.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Miyahisa
authors.affiliation: Biomolecular Research Laboratories, Pharmaceutical Research Division, Takeda Pharmaceutical Company Ltd., 26-1, Muraoka-higashi 2-chome, Fujisawa, Kanagawa 251-8555 (Japan).
authors.forename: Tomoya
authors.initials: T
authors.lastname: Sameshima
authors.affiliation: Modeling & Simulation, Global DMPK, Takeda California, Inc., 10410 Science Center Drive, San Diego, CA 92121 (USA).
authors.forename: Mark S
authors.initials: MS
authors.lastname: Hixon
mesh_terms: D023381:Endpoint Determination; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D015394:Molecular Structure; D009025:Morpholines / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D009025:Morpholines; C420268:Canertinib; D066246:ErbB Receptors
keywords: covalent inhibitors; drug discovery; enzyme kinetics; irreversible inhibition