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DNA topoisomerase I from Diplococcus pneumoniae.

Authors
Type
Published Article
Journal
Biomedica biochimica acta
Publication Date
Volume
48
Issue
1
Pages
69–76
Identifiers
PMID: 2549982
Source
Medline
License
Unknown

Abstract

A type I topoisomerase has been purified from Diplococcus pneumoniae using phosphocellulose and hydroxylapatite chromatography. The purified enzyme catalyses the relaxation of negatively supercoiled DNA. The relaxation requires Mg2+ and is favoured by 0.2 M monovalent cations. The enzyme does not exhibit catenating or supercoiling activities. Using circular pBR322 DNA from dam+- and dam- -hosts as substrates for the enzyme, the relaxation reaction proceeds with somewhat higher efficiency with plasmids containing methylated adenine in GATC sequences. Plasmids from dcm+- and dcm- -hosts show no difference in reactivity.

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