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A nuclease that releases one nucleotide at a time, serially, beginning at one end of a polynucleotide (nucleic acid); several have been prepared from Escherichia coli, designated e. I, e. II, etc.; e. III, which removes nucleotides from 3′ ends of DNA, is used in DNA sequencing. Cf.:endonuclease.
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exo·nu·cle·ase .ek-sō-'n(y)ü-klē-.ās, -.āz n an enzyme that breaks down a nucleic acid by removing nucleotides one by one from the end of a chain compare ENDONUCLEASE
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exo·nu·cle·ase (ek″so-nooґkle-ās) [EC 3.1.11–16] any nuclease specifically catalyzing the hydrolysis of terminal bonds of deoxyribonucleotide or ribonucleotide chains, releasing mononucleotides. Cf. endonuclease.Medical dictionary. 2011.