scholarly journals Protocol-Dependent Differences in IC50 Values Measured in Human Ether-Á-Go-Go–Related Gene Assays Occur in a Predictable Way and Can Be Used to Quantify State Preference of Drug Binding

2019 ◽  
Vol 95 (5) ◽  
pp. 537-550 ◽  
Author(s):  
William Lee ◽  
Monique J. Windley ◽  
Matthew D. Perry ◽  
Jamie I. Vandenberg ◽  
Adam P. Hill
Keyword(s):  
Drug Binding ◽  
Related Gene ◽  
State Preference ◽  
Ic50 Values

scholarly journals Protocol-dependent differences in IC50 values measured in hERG assays occur in a predictable way and can be used to quantify state preference of drug binding

2019 ◽  
Author(s):  
William Lee ◽  
Monique J. Windley ◽  
Matthew D. Perry ◽  
Jamie I. Vandenberg ◽  
Adam P. Hill
Keyword(s):  
State Dependence ◽  
Drug Binding ◽  
Machine Learning Algorithms ◽  
Drug Induced ◽  
Preferential Binding ◽  
State Preference ◽  
Proarrhythmic Risk ◽  
Ic50 Values ◽  
Novel Method ◽  
Open Versus

AbstractCurrent guidelines around preclinical screening for drug-induced arrhythmias require the measurement of the potency of block of Kv11.1 channels as a surrogate for risk. A shortcoming of this approach is that the measured IC50 of Kv11.1 block varies widely depending on the voltage protocol used in electrophysiological assays. In this study, we aimed to investigate the factors that that contribute to these differences and to identify whether it is possible to make predictions about protocol-dependent block that might facilitate comparison of potencies measured using different assaysOur data demonstrate that state preferential binding, together with drug binding kinetics and trapping, is an important determinant of the protocol-dependence of Kv11.1 block. We show for the first time that differences in IC50 measured between protocols occurs in a predictable way, such that machine learning algorithms trained using a selection of simple voltage protocols can indeed predict protocol-dependent potency. Furthermore, we also show that a drug’s preference for binding to the open versus the inactivated state of Kv11.1 can also be inferred from differences in IC50 measured between protocols.Our work therefore identifies how state preferential drug binding is a major determinant of the protocol dependence of IC50 measured in preclinical Kv11.1 assays. It also provides a novel method for quantifying the state dependence of Kv11.1 drug binding that will facilitate the development of more complete models of drug binding to Kv11.1 and improve our understanding of proarrhythmic risk associated with compounds that block Kv11.1.

scholarly journals Biophysical Characterization of Novel DNA Aptamers against K103N/Y181C Double Mutant HIV-1 Reverse Transcriptase

Molecules ◽  
2022 ◽  
Vol 27 (1) ◽  
pp. 285
Author(s):  
Siriluk Ratanabunyong ◽  
Supaphorn Seetaha ◽  
Supa Hannongbua ◽  
Saeko Yanaka ◽  
Maho Yagi-Utsumi ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Double Mutant ◽  
Binding Pocket ◽  
Drug Binding ◽  
Dna Aptamer ◽  
Hek293 Cells ◽  
Dna Aptamers ◽  
Ic50 Values ◽  
Methionine Residues ◽  
Hiv 1

The human immunodeficiency virus type-1 Reverse Transcriptase (HIV-1 RT) plays a pivotal role in essential viral replication and is the main target for antiviral therapy. The anti-HIV-1 RT drugs address resistance-associated mutations. This research focused on isolating the potential specific DNA aptamers against K103N/Y181C double mutant HIV-1 RT. Five DNA aptamers showed low IC50 values against both the KY-mutant HIV-1 RT and wildtype (WT) HIV-1 RT. The kinetic binding affinity forms surface plasmon resonance of both KY-mutant and WT HIV-1 RTs in the range of 0.06–2 μM and 0.15–2 μM, respectively. Among these aptamers, the KY44 aptamer was chosen to study the interaction of HIV-1 RTs-DNA aptamer complex by NMR experiments. The NMR results indicate that the aptamer could interact with both WT and KY-mutant HIV-1 RT at the NNRTI drug binding pocket by inducing a chemical shift at methionine residues. Furthermore, KY44 could inhibit pseudo-HIV particle infection in HEK293 cells with nearly 80% inhibition and showed low cytotoxicity on HEK293 cells. These together indicated that the KY44 aptamer could be a potential inhibitor of both WT and KY-mutant HIV-RT.

Local Anesthetic Interaction with Human Ether-a-go-go –related Gene (HERG) Channels

2005 ◽  
Vol 103 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Cornelia C. Siebrands ◽  
Nicole Schmitt ◽  
Patrick Friederich
Keyword(s):  
Local Anesthetics ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Drug Binding ◽  
Related Gene ◽  
Wild Type ◽  
Ovary Cells ◽  
Whole Cell Patch Clamp ◽  
Amino Amide ◽  
Herg Channels

Background Human ether-a-go-go-related gene (HERG) potassium channels constitute a potential target involved in cardiotoxic side effects of amino-amide local anesthetics. The molecular interaction site of these low-affinity blockers with HERG channels is currently unknown. The aim of this study was to determine the effect of the mutations Y652A and F656A in the putative drug binding region of HERG on the inhibition by bupivacaine, ropivacaine, and mepivacaine. Methods The authors examined the inhibition of wild-type and mutant HERG channels, transiently expressed in Chinese hamster ovary cells by bupivacaine, ropivacaine, and mepivacaine. Whole cell patch clamp recordings were performed at room temperature. Results Inhibition of HERG wild-type and mutant channels by the different local anesthetics was concentration dependent, stereoselective, and reversible. The sensitivity decreased in the order bupivacaine > ropivacaine > mepivacaine for wild-type and mutant channels. The mutant channels were approximately 4-30 times less sensitive to the inhibitory action of the different local anesthetics than the wild-type channel. The concentration-response data were described by Hill functions (bupivacaine: wild-type IC50 = 22 +/- 2 microm, n = 38; Y652A IC50 = 95 +/- 5 microm, n = 31). The mutations resulted in a change of the stereoselectivity of HERG channel block by ropivacaine. The potency of the local anesthetics to inhibit wild-type and mutant channels correlated with the lipophilicity of the drug (r > 0.9). Conclusions These results indicate that local anesthetics specifically but not exclusively interact with the aromatic residues Y652 and F656 in S6 of HERG channels.

Drug Binding to the Inactivated State Is Necessary but Not Sufficient for High-Affinity Binding to Human Ether-à-go-go-Related Gene Channels

2008 ◽  
Vol 74 (5) ◽  
pp. 1443-1452 ◽  
Author(s):  
Mark J. Perrin ◽  
Philip W. Kuchel ◽  
Terence J. Campbell ◽  
Jamie I. Vandenberg
Keyword(s):  
Drug Binding ◽  
Affinity Binding ◽  
Related Gene ◽  
High Affinity Binding ◽  
High Affinity

Effect of piperacillin on morphology and viability of gram-negative bacteria

1984 ◽  
Vol 42 ◽  
pp. 218-219
Author(s):  
R. H. Liss
Keyword(s):  
Inhibitory Concentration ◽  
Cytoplasmic Membrane ◽  
Drug Binding ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Drug Induced ◽  
Penicillin Binding Proteins ◽  
Lactam Antibiotic ◽  
Drug Free ◽  
Tube Dilution

Piperacillip (PIP) is b-[D(-)-α-(4-ethy1-2,3-dioxo-l-piperzinylcar-bonylamino)-α-phenylacetamido]-penicillanate. The broad spectrum semisynthetic β-lactam antibiotic is believed to effect bactericidal activity through its affinity for penicillin-binding proteins (PBPs), enzymes on the bacterial cytoplasmic membrane that control elongation and septation during cell growth and division. The purpose of this study was to correlate penetration and binding of 14C-PIP in bacterial cells with drug-induced lethal changes assessed by microscopic, microbiologic and biochemical methods.The bacteria used were clinical isolates of Escherichia coli and Pseudomonas aeruginosa (Figure 1). Sensitivity to the drug was determined by serial tube dilution in Trypticase Soy Broth (BBL) at an inoculum of 104 organisms/ml; the minimum inhibitory concentration of piperacillin for both bacteria was 1 μg/ml. To assess drug binding to PBPs, the bacteria were incubated with 14C-PIP (5 μg/0.09 μCi/ml); controls, in drug-free medium.

Khat affects apoptosis and related gene XIAP and Smac expression following transient focal ischemia in rats

2010 ◽  
Vol 34 (8) ◽  
pp. S16-S16
Author(s):  
Fang‑fang Bi ◽  
Hadi M. Mujlli ◽  
Yue‑qiang Hu ◽  
Fa‑fa Tian ◽  
Zhi‑guo Wu ◽  
...  
Keyword(s):  
Focal Ischemia ◽  
Related Gene ◽  
Transient Focal Ischemia
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