Single-strand-specific DNase activity is an inherent property of the 140-kDa protein of the snake venom exonuclease

Abstract

Polyclonal antibodies against the exonuclease from Crotalus adamanteus venom (the 140-kDa protein) inhibit both the exonucleolytic and the single-strand-specific endonucleolytic activities, present in the exonuclease preparation. The antibodies also diminish the ability of the enzyme to split the negatively supercoiled Bluescript KS + in the AT-rich fragment near-by the transcription termination site of the Ampicillin gene. Therefore the single-strand-specific endonucleolytic activity was attributed to the protein molecule of the exonuclease. The processivity of the exonucleolytic action was found to be less than 3 monomers as indicated by the heparin trapping method.