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DNA-relaxing enzyme from Micrococcus luteus.
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MedLine Citation:
PMID:  202927     Owner:  NLM     Status:  MEDLINE    
A DNA-relaxing enzyme which catalyzes the conversion of superhelical DNA to a non-superhelical covalently closed form has been purified from Micrococcus luteus to near homogeneity by two chromatographic steps. The enzyme is a single polypeptide chain. As determined by sodium dodecyl sulfate - polyacrylamide gel electrophoresis and gel filtration on Sephadex G 150, the molecular weight is 115,000. The DNA-relaxing activity determined as a function of enzyme concentration follows a sigmoidal curve. The enzyme requires Mg++ for activity. In the presence of 4.5 mM Mg++ addition of 50-250 mM KCl yields incompletely relaxed DNA molecules (intermediates); intermediates are also observed in the absence of KCl, when the reaction is carried out at 0 degree C or at Mg++ concentrations exceeding 10 mM.
R Hecht; H W Thielmann
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Nucleic acids research     Volume:  4     ISSN:  0305-1048     ISO Abbreviation:  Nucleic Acids Res.     Publication Date:  1977 Dec 
Date Detail:
Created Date:  1978-03-21     Completed Date:  1978-03-21     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0411011     Medline TA:  Nucleic Acids Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  4235-47     Citation Subset:  IM    
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MeSH Terms
DNA Topoisomerases, Type I / isolation & purification,  metabolism*
Magnesium / pharmacology
Micrococcus / enzymology*
Molecular Weight
Reg. No./Substance:
7439-95-4/Magnesium; EC Topoisomerases, Type I

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Full Text
Journal Information
Journal ID (nlm-ta): Nucleic Acids Res
ISSN: 0305-1048
ISSN: 1362-4962
Article Information
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Print publication date: Month: 12 Year: 1977
Volume: 4 Issue: 12
First Page: 4235 Last Page: 4247
ID: 343237
PubMed Id: 202927

DNA-relaxing enzyme from Micrococcus luteus.
R Hecht
H W Thielmann

Article Categories:
  • Research Article

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