{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,19]],"date-time":"2025-11-19T06:53:19Z","timestamp":1763535199998,"version":"build-2065373602"},"reference-count":37,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2013,3,25]],"date-time":"2013-03-25T00:00:00Z","timestamp":1364169600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Sensors capable of quantitative real-time measurements may present the easiest and most accurate way to study enzyme activities. Here we present a novel DNA-based sensor for specific and quantitative real-time measurement of the enzymatic activity of the essential human enzyme, topoisomerase I. The basic design of the sensor relies on two DNA strands that hybridize to form a hairpin structure with a fluorophore-quencher  pair. The quencher moiety is released from the sensor upon reaction with human  topoisomerase I thus enabling real-time optical measurement of enzymatic activity. The sensor is specific for topoisomerase I even in raw cell extracts and presents a simple mean of following enzyme kinetics using standard laboratory equipment such as a qPCR machine or fluorimeter. Human topoisomerase I is a well-known target for the clinically used anti-cancer drugs of the camptothecin family. The cytotoxic effect of camptothecins correlates directly with the intracellular topoisomerase I activity. We therefore envision that the presented sensor may find use for the prediction of cellular drug response. Moreover, inhibition of topoisomerase I by camptothecin is readily detectable using the presented DNA sensor, suggesting a potential application of the sensor for first line screening for potential topoisomerase I targeting anti-cancer drugs.<\/jats:p>","DOI":"10.3390\/s130404017","type":"journal-article","created":{"date-parts":[[2013,3,26]],"date-time":"2013-03-26T04:34:12Z","timestamp":1364272452000},"page":"4017-4028","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["DNA-Based Sensor for Real-Time Measurement of the Enzymatic Activity of Human Topoisomerase I"],"prefix":"10.3390","volume":"13","author":[{"given":"L\u00e6rke","family":"Marcussen","sequence":"first","affiliation":[{"name":"Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark"},{"name":"Department of Pathology, Aarhus University Hospital, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Morten","family":"Jepsen","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark"},{"name":"Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Emil","family":"Kristoffersen","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark"},{"name":"Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Oskar","family":"Franch","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark"},{"name":"Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joanna","family":"Proszek","sequence":"additional","affiliation":[{"name":"Department of Pathology, Aarhus University Hospital, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yi-Ping","family":"Ho","sequence":"additional","affiliation":[{"name":"Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Magnus","family":"Stougaard","sequence":"additional","affiliation":[{"name":"Department of Pathology, Aarhus University Hospital, Aarhus C 8000, Denmark"},{"name":"Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Birgitta","family":"Knudsen","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark"},{"name":"Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2013,3,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"144","DOI":"10.1016\/j.bios.2012.01.034","article-title":"Sensitive detection of endonuclease activity and inhibition using gold nanorods","volume":"34","author":"Deng","year":"2012","journal-title":"Biosens. 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