The Experts below are selected from a list of 252 Experts worldwide ranked by ideXlab platform
Robert M. Snapka - One of the best experts on this subject based on the ideXlab platform.
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Topoisomerase II poisoning by ICRF-193.
Journal of Biological Chemistry, 2001Co-Authors: Kuan-chun Huang, Hanlin Gao, Kenneth K. Chan, Linus L. Shen, Edith F. Yamasaki, Dale Grabowski, Shujun Liu, Ram Ganapathi, Robert M. SnapkaAbstract:Abstract Antineoplastic bis(dioxopiperazine)s, such as meso-2,3-bis(2,6-dioxopiperazin-4-yl)butane (ICRF-193), are widely believed to be only catalytic inhibitors of topoisomerase II. However, topoisomerase inhibitors have little or no antineoplastic activity unless they are topoisomerase poisons, a special subclass of topoisomerase-targeting drugs that stabilize topoisomerase-DNA strand passing intermediates and thus cause the topoisomerase to become a cytotoxic DNA-damaging agent. Here we report that ICRF-193 is a very significant topoisomerase II poison. Detection of topoisomerase II poisoning by ICRF-193 required the use of a chaotropic Protein Denaturant in the topoisomerase poisoning assays. ICRF-193 caused dose-dependent cross-linking of human topoisomerase IIβ to DNA and stimulated topoisomerase IIβ-mediated DNA cleavage at specific sites on 32P-end-labeled DNA. Human topoisomerase IIα-mediated DNA cleavage was stimulated to a lesser extent by ICRF-193. In vivo experiments with MCF-7 cells also showed the requirement of a chaotropic Protein Denaturant in the assays and selectivity for the β-isozyme of human topoisomerase II. Studies with two topoisomerase IIβ-negative cell model systems confirmed significant topoisomerase II poisoning by ICRF-193 in the wild type cells and were consistent with β-isozyme selectivity. Common use of only the detergent, SDS, in assays may have led to failure to detect topoisomerase II poisoning by ICRF-193 in earlier studies.
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Chloroquinoxaline Sulfonamide (NSC 339004) Is a Topoisomerase IIα/β Poison
Cancer research, 2000Co-Authors: Hanlin Gao, Edith Yamasaki, Kenneth K. Chan, Linus L. Shen, Robert M. SnapkaAbstract:Chloroquinoxaline sulfonamide (chlorosulfaquinoxaline, CQS, NSC 339004) is active against murine and human solid tumors. On the basis of its structural similarity to the topoisomerase IIβ-specific drug XK469, CQS was tested and found to be both a topoisomerase-IIα and a topoisomerase-IIβ poison. Topoisomerase II poisoning by CQS is essentially undetectable in assays using the common Protein Denaturant SDS, but easily detectable with strong chaotropic Protein Denaturants. The finding that detection of topoisomerase poisoning can be so dependent on the Protein Denaturant used in the assay has implications for drug discovery efforts and for our understanding of topoisomerase poisons.
Hanlin Gao - One of the best experts on this subject based on the ideXlab platform.
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Topoisomerase II poisoning by ICRF-193.
Journal of Biological Chemistry, 2001Co-Authors: Kuan-chun Huang, Hanlin Gao, Kenneth K. Chan, Linus L. Shen, Edith F. Yamasaki, Dale Grabowski, Shujun Liu, Ram Ganapathi, Robert M. SnapkaAbstract:Abstract Antineoplastic bis(dioxopiperazine)s, such as meso-2,3-bis(2,6-dioxopiperazin-4-yl)butane (ICRF-193), are widely believed to be only catalytic inhibitors of topoisomerase II. However, topoisomerase inhibitors have little or no antineoplastic activity unless they are topoisomerase poisons, a special subclass of topoisomerase-targeting drugs that stabilize topoisomerase-DNA strand passing intermediates and thus cause the topoisomerase to become a cytotoxic DNA-damaging agent. Here we report that ICRF-193 is a very significant topoisomerase II poison. Detection of topoisomerase II poisoning by ICRF-193 required the use of a chaotropic Protein Denaturant in the topoisomerase poisoning assays. ICRF-193 caused dose-dependent cross-linking of human topoisomerase IIβ to DNA and stimulated topoisomerase IIβ-mediated DNA cleavage at specific sites on 32P-end-labeled DNA. Human topoisomerase IIα-mediated DNA cleavage was stimulated to a lesser extent by ICRF-193. In vivo experiments with MCF-7 cells also showed the requirement of a chaotropic Protein Denaturant in the assays and selectivity for the β-isozyme of human topoisomerase II. Studies with two topoisomerase IIβ-negative cell model systems confirmed significant topoisomerase II poisoning by ICRF-193 in the wild type cells and were consistent with β-isozyme selectivity. Common use of only the detergent, SDS, in assays may have led to failure to detect topoisomerase II poisoning by ICRF-193 in earlier studies.
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Chloroquinoxaline Sulfonamide (NSC 339004) Is a Topoisomerase IIα/β Poison
Cancer research, 2000Co-Authors: Hanlin Gao, Edith Yamasaki, Kenneth K. Chan, Linus L. Shen, Robert M. SnapkaAbstract:Chloroquinoxaline sulfonamide (chlorosulfaquinoxaline, CQS, NSC 339004) is active against murine and human solid tumors. On the basis of its structural similarity to the topoisomerase IIβ-specific drug XK469, CQS was tested and found to be both a topoisomerase-IIα and a topoisomerase-IIβ poison. Topoisomerase II poisoning by CQS is essentially undetectable in assays using the common Protein Denaturant SDS, but easily detectable with strong chaotropic Protein Denaturants. The finding that detection of topoisomerase poisoning can be so dependent on the Protein Denaturant used in the assay has implications for drug discovery efforts and for our understanding of topoisomerase poisons.
Linus L. Shen - One of the best experts on this subject based on the ideXlab platform.
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Topoisomerase II poisoning by ICRF-193.
Journal of Biological Chemistry, 2001Co-Authors: Kuan-chun Huang, Hanlin Gao, Kenneth K. Chan, Linus L. Shen, Edith F. Yamasaki, Dale Grabowski, Shujun Liu, Ram Ganapathi, Robert M. SnapkaAbstract:Abstract Antineoplastic bis(dioxopiperazine)s, such as meso-2,3-bis(2,6-dioxopiperazin-4-yl)butane (ICRF-193), are widely believed to be only catalytic inhibitors of topoisomerase II. However, topoisomerase inhibitors have little or no antineoplastic activity unless they are topoisomerase poisons, a special subclass of topoisomerase-targeting drugs that stabilize topoisomerase-DNA strand passing intermediates and thus cause the topoisomerase to become a cytotoxic DNA-damaging agent. Here we report that ICRF-193 is a very significant topoisomerase II poison. Detection of topoisomerase II poisoning by ICRF-193 required the use of a chaotropic Protein Denaturant in the topoisomerase poisoning assays. ICRF-193 caused dose-dependent cross-linking of human topoisomerase IIβ to DNA and stimulated topoisomerase IIβ-mediated DNA cleavage at specific sites on 32P-end-labeled DNA. Human topoisomerase IIα-mediated DNA cleavage was stimulated to a lesser extent by ICRF-193. In vivo experiments with MCF-7 cells also showed the requirement of a chaotropic Protein Denaturant in the assays and selectivity for the β-isozyme of human topoisomerase II. Studies with two topoisomerase IIβ-negative cell model systems confirmed significant topoisomerase II poisoning by ICRF-193 in the wild type cells and were consistent with β-isozyme selectivity. Common use of only the detergent, SDS, in assays may have led to failure to detect topoisomerase II poisoning by ICRF-193 in earlier studies.
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Chloroquinoxaline Sulfonamide (NSC 339004) Is a Topoisomerase IIα/β Poison
Cancer research, 2000Co-Authors: Hanlin Gao, Edith Yamasaki, Kenneth K. Chan, Linus L. Shen, Robert M. SnapkaAbstract:Chloroquinoxaline sulfonamide (chlorosulfaquinoxaline, CQS, NSC 339004) is active against murine and human solid tumors. On the basis of its structural similarity to the topoisomerase IIβ-specific drug XK469, CQS was tested and found to be both a topoisomerase-IIα and a topoisomerase-IIβ poison. Topoisomerase II poisoning by CQS is essentially undetectable in assays using the common Protein Denaturant SDS, but easily detectable with strong chaotropic Protein Denaturants. The finding that detection of topoisomerase poisoning can be so dependent on the Protein Denaturant used in the assay has implications for drug discovery efforts and for our understanding of topoisomerase poisons.
Kenneth K. Chan - One of the best experts on this subject based on the ideXlab platform.
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Topoisomerase II poisoning by ICRF-193.
Journal of Biological Chemistry, 2001Co-Authors: Kuan-chun Huang, Hanlin Gao, Kenneth K. Chan, Linus L. Shen, Edith F. Yamasaki, Dale Grabowski, Shujun Liu, Ram Ganapathi, Robert M. SnapkaAbstract:Abstract Antineoplastic bis(dioxopiperazine)s, such as meso-2,3-bis(2,6-dioxopiperazin-4-yl)butane (ICRF-193), are widely believed to be only catalytic inhibitors of topoisomerase II. However, topoisomerase inhibitors have little or no antineoplastic activity unless they are topoisomerase poisons, a special subclass of topoisomerase-targeting drugs that stabilize topoisomerase-DNA strand passing intermediates and thus cause the topoisomerase to become a cytotoxic DNA-damaging agent. Here we report that ICRF-193 is a very significant topoisomerase II poison. Detection of topoisomerase II poisoning by ICRF-193 required the use of a chaotropic Protein Denaturant in the topoisomerase poisoning assays. ICRF-193 caused dose-dependent cross-linking of human topoisomerase IIβ to DNA and stimulated topoisomerase IIβ-mediated DNA cleavage at specific sites on 32P-end-labeled DNA. Human topoisomerase IIα-mediated DNA cleavage was stimulated to a lesser extent by ICRF-193. In vivo experiments with MCF-7 cells also showed the requirement of a chaotropic Protein Denaturant in the assays and selectivity for the β-isozyme of human topoisomerase II. Studies with two topoisomerase IIβ-negative cell model systems confirmed significant topoisomerase II poisoning by ICRF-193 in the wild type cells and were consistent with β-isozyme selectivity. Common use of only the detergent, SDS, in assays may have led to failure to detect topoisomerase II poisoning by ICRF-193 in earlier studies.
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Chloroquinoxaline Sulfonamide (NSC 339004) Is a Topoisomerase IIα/β Poison
Cancer research, 2000Co-Authors: Hanlin Gao, Edith Yamasaki, Kenneth K. Chan, Linus L. Shen, Robert M. SnapkaAbstract:Chloroquinoxaline sulfonamide (chlorosulfaquinoxaline, CQS, NSC 339004) is active against murine and human solid tumors. On the basis of its structural similarity to the topoisomerase IIβ-specific drug XK469, CQS was tested and found to be both a topoisomerase-IIα and a topoisomerase-IIβ poison. Topoisomerase II poisoning by CQS is essentially undetectable in assays using the common Protein Denaturant SDS, but easily detectable with strong chaotropic Protein Denaturants. The finding that detection of topoisomerase poisoning can be so dependent on the Protein Denaturant used in the assay has implications for drug discovery efforts and for our understanding of topoisomerase poisons.
Martin Gruebele - One of the best experts on this subject based on the ideXlab platform.
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dodine as a transparent Protein Denaturant for circular dichroism and infrared studies
Protein Science, 2016Co-Authors: Drishti Guin, Kori Sye, Kapil Dave, Martin GruebeleAbstract:The fungicide dodine combines the cooperative denaturation properties of guanidine with the mM denaturation activity of SDS. It was previously tested only on two small model Proteins. Here we show that it can be used as a chemical Denaturant for phosphoglycerate kinase (PGK), a much larger two-domain enzyme. In addition to its properties as a chemical Denaturant, dodine facilitates thermal denaturation of PGK, and we show for the first time that it also facilitates pressure denaturation of a Protein. Much higher quality circular dichroism and amide I' infrared spectra of PGK can be obtained in dodine than in guanidine, opening the possibility for use of dodine as a Denaturant when UV or IR detection is desirable. One caution is that dodine denaturation, like other detergent-based Denaturants, is less reversible than guanidine denaturation.
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Dodine as a Protein Denaturant: the best of two worlds?
The journal of physical chemistry. B, 2013Co-Authors: Hannah Gelman, Tatyana Perlova, Martin GruebeleAbstract:Traditional Denaturants such as urea and guanidinium ion unfold Proteins in a cooperative “all-or-none” fashion. However, their high working concentration in combination with their strong absorption in the far ultraviolet region make it impossible to measure high quality circular dichroism or infrared spectra, which are commonly used to detect changes in Protein secondary structure. On the other hand, detergents such as dodecyl sulfate destabilize native Protein conformation at low millimolar concentrations and are UV transparent, but they denature Proteins more gradually than guanidinium or urea. In this work, we studied the denaturation properties of the fungicide dodecylguanidinium acetate (dodine), which combines both Denaturants into one. We show that dodine unfolds some small Proteins at millimolar concentrations, facilitates temperature denaturation, and is transparent enough at its working concentration, unlike guanidinium, to measure full range circular dichroism spectra. Our results also suggest...
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New Powerful Protein Denaturant
Biophysical Journal, 2013Co-Authors: Tatyana Perlova, Hannah Gelman, Martin GruebeleAbstract:Traditional Denaturants such as urea and guanidinium hydrochloride effectively unfold a variety of Proteins in an “all-or-none” fashion. However their high working concentration in combination with the strong absorption below 210 nm make it impossible to measure high quality circular dichroism spectra, which are commonly used to detect changes in Protein secondary structure. Detergents on the other hand destabilize native Protein conformation at the extremely low concentration of several millimolar and are UV transparent, but they do not denature Proteins as effectively as guanidinium or urea. In this work we studied the denaturation properties of the dodecylguanidine acetate which can be considered as a chemical combination of detergent and guanidinium. We have shown that dodecylguanidine acetate unfolds the Protein at the millimolar concentration and is transparent enough to measure full range circular dichroism spectra. Our results also suggest that dodecylguanidine acetate allows to fine-tune the degree of Protein unfolding unlike traditional “all-or-none” Denaturants.
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Dodine as a Protein Denaturant: The Best of Two Worlds?
The Journal of Physical Chemistry, 2013Co-Authors: Hannah Gelman, Tatyana Perlova, Martin GruebeleAbstract:Traditional Denaturants such as urea and guanidinium ion unfold Proteins in a cooperative “all-or-none” fashion. However, their high working concentration in combination with their strong absorption in the far ultraviolet region make it impossible to measure high quality circular dichroism or infrared spectra, which are commonly used to detect changes in Protein secondary structure. On the other hand, detergents such as dodecyl sulfate destabilize native Protein conformation at low millimolar concentrations and are UV transparent, but they denature Proteins more gradually than guanidinium or urea. In this work, we studied the denaturation properties of the fungicide dodecylguanidinium acetate (dodine), which combines both Denaturants into one. We show that dodine unfolds some small Proteins at millimolar concentrations, facilitates temperature denaturation, and is transparent enough at its working concentration, unlike guanidinium, to measure full range circular dichroism spectra. Our results also suggest that dodine allows fine-tuning of the Protein’s unfolded state, unlike traditional “all-or-none” Denaturants.