A DNase from the trypanosomatid Crithidia fasciculata

C. J. Li, K. Y. Hwa, P. T. Englund

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9 Scopus citations


We have purified to homogeneity a DNase from a Crithidia fasciculata crude mitochondrial lysate. The enzyme is present in two forms, either as a 32 kDa polypeptide or as a multimer containing the 32 kDa polypeptide in association with a 56 kDa polypeptide. Native molecular weight measurements indicate that these forms are a monomer and possibly an α2β2 tetramer, respectively. The monomeric and multimeric forms of the enzyme are similar in their catalytic activities. Both digest double-stranded DNA about twice as efficiently as single-stranded DNA. They introduce single-strand breaks into a supercoiled plasmid but do not efficiently make double-strand breaks. They degrade a linearized plasmid more efficiently than a nicked plasmid. Both enzymes degrade a 5'-32P-labeled double-stranded oligonucleotide to completion, with the 5'-terminal nucleotide ultimately being released as a 5'-mononucleotide. One difference between the monomeric and multimeric forms of the enzyme, demonstrated by a band shift assay, is that the multimeric form binds tightly to double-stranded DNA, possibly aggregating it.

Original languageEnglish (US)
Pages (from-to)4426-4433
Number of pages8
JournalNucleic acids research
Issue number21
StatePublished - 1995
Externally publishedYes

ASJC Scopus subject areas

  • Genetics


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