Den 1, den 2 and den 3, ATP-inhibited deoxyribonucleases from Dropsophila embryonic nuclei

Three Drosophila embryonic deoxyribonucleases, designated den1, den2 and de n3, are identified in nuclear extracts separated by glycerol density gradie nt centrifugation. Den1, removes short products from the 5'-ends of single- stranded DNA or double-stranded DNA with either blunt or 5'-recessed termin i. Den2 is inactive with single-stranded DNA and acts as 3'-exonuclease wit h double-stranded DNA possessing either blunt or 3'-recessed termini. Den3 preferentially uses partial duplex DNA containing single-stranded gap and i t catalyzes hydrolysis, in 3'-5' direction, of one of the shorter strands t hat flank the gap. Nucleolytic activities of den1, den2 and den3 are inhibi ted with ATP.