A novel single-stranded DNA-specific endonuclease from pea chloroplasts

Kumar, D. ; Mukherjee, S. ; Reddy, M. K. ; Tewari, K. K. (1995) A novel single-stranded DNA-specific endonuclease from pea chloroplasts Journal of Experimental Botany, 46 (7). pp. 767-776. ISSN 0022-0957

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Official URL: http://jxb.oxfordjournals.org/content/46/7/767.sho...

Related URL: http://dx.doi.org/10.1093/jxb/46.7.767


A nuclease with novel activities has been isolated and purified to apparent homogeneity from pea chloroplasts. The enzyme prefers single-stranded (ss) circular DNA; its activity being 1500-fold higher with the ss circular DNA than with the linear double-stranded DNA substrates. The single-stranded DNase activity is stable at moderately high temperature (50 °C) and inhibited in the presence of 75 mM NaCl. It binds negatively supercoiled DNA in the stoichiometric fashion, but behaves catalytically on the single-stranded circular DNA. Although the DNase activity does not recognize any specific nucleotide sequence, the co-operative mode of activity seems to be a novel one. The protein is a monomer of 35 kDa and binds with DNA predominantly through electrostatic interactions. The drug distamycin blocks the endonuclease activity suggesting that the protein binds at the minor groove of DNA. A RNase activity has also been found associated with the ss-DNA endonuclease.

Item Type:Article
Source:Copyright of this article belongs to Oxford University Press.
Keywords:Pea; Chloroplast; Endonuclease
ID Code:82332
Deposited On:10 Feb 2012 12:20
Last Modified:10 Feb 2012 12:20

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