%0 Journal Article
%T DNA-Based Sensor for Real-Time Measurement of the Enzymatic Activity of Human Topoisomerase I
%A L£¿rke Bay Marcussen
%A Morten Leth Jepsen
%A Emil Laust Kristoffersen
%A Oskar Franch
%A Joanna Proszek
%A Yi-Ping Ho
%A Magnus Stougaard
%A Birgitta Ruth Knudsen
%J Sensors
%D 2013
%I MDPI AG
%R 10.3390/s130404017
%X 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.
%K real-time activity measurement
%K DNA sensor
%K fluorophore-quencher pair
%K topoisomerase I
%K cancer treatment
%K camptothecin
%U http://www.mdpi.com/1424-8220/13/4/4017