title: A second form of the single-strand specific endonuclease of Neurospora crassa which is associated with a double-strand exonuclease.
abstract: A second form of single-strand specific endonuclease, which is stable to heating up to 74 degrees C and does not bind strongly to phosphocellulose, has been partially purified from extracts of mycelia of wild-type Neurospora crassa. The endonuclease is associated with an equally heat-stable exonuclease which degrades linear but not circular double-stranded DNA and does not attack double-stranded RNA. The exonuclease probably also degrades single-stranded DNA. Both endonuclease and exonuclease activities are inhibited by 0.1-0.5 mM ATP. The exonuclease is preferentially inhibited by a variety of agents and preferentially inactivated by trypsin. A DNA-unwinding activity has also been detected in the nuclease preparation. Protease(s) present in the nuclease preparation destroy the DNA-unwinding and exonuclease activities on incubation at 37 degrees C, but do not affect the endonuclease activity. However, the heat-stability and chromatographic properties of the endonuclease are affected by this treatment. The altered properties of the endonuclease are very similar to those of the single-strand specific endonuclease which has been previously described. The combined nuclease activities of the unaltered preparational make up a putative recombination nuclease of N. crassa.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D002413:Cations, Divalent; D004247:DNA; D004277:DNA, Single-Stranded; D003851:Deoxyribonucleases / Q000302:isolation & purification / Q000378:metabolism; D004355:Drug Stability; D004492:Edetic Acid / Q000494:pharmacology; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism; D005092:Exonucleases / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D009491:Neurospora / Q000201:enzymology*; D009492:Neurospora crassa / Q000201:enzymology*; D009690:Nucleic Acid Conformation; D009994:Osmolar Concentration; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D004277:DNA, Single-Stranded; D012965:Sodium Chloride; D000255:Adenosine Triphosphate; D004247:DNA; D004492:Edetic Acid; D003851:Deoxyribonucleases; D004720:Endonucleases; D005092:Exonucleases