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Mitochondrial DNA topoisomerase I from human platelets
Journal article   Peer reviewed

Mitochondrial DNA topoisomerase I from human platelets

Marshall J Kosovsky and Gerald Soslau
Biochimica et biophysica acta, Protein structure and molecular enzymology, v 1078(1)
1991
PMID: 1646636

Abstract

Mitochondrion Camptothecin DNA topoisomerase I Human platelet
An anucleated cell system has been used for the first time to study mitochondrial topoisomerase activity. Mitochondrial extracts from human blood platelets contained type I topoisomerase. The type I classification was based on ATP-independent activity, inhibition by ATP or camptothecin, and the lack of inhibition by novobiocin. Platelet mitochondrial topoisomerase I relaxation activity was inhibited linearly by increasing concentrations of EGTA. Topoisomerase activity 90% inhibited by 175 μM EGTA was partially restored to 16 and 50% of the initial level of activity by the subsequent addition of 50 and 100 μM Ca 2+, respectively. Additionally, results from studies of partially purified platelet mitochondrial topoisomerase I were consistent with the crude extract data. This work supports the hypothesis that platelet mitochondria contain a type I topoisomerase that is biochemically distinct from that previously isolated and characterized from cell nuclei.

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Web of Science research areas
Biochemistry & Molecular Biology
Biophysics
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