title: An immunochemical study of Neurospora nucleases.
abstract: Nucleases derived from Neurospora crassa mycelia with neutral single-strand (ss) endodeoxyribonuclease activity have been examined by immunochemical techniques and by sodium dodecyl sulfate - DNA gel electrophoresis. All of the intracellular nucleases, which have different divalent metal ion requirements, different strand specificities with single- and double-strand DNA, different modes of action on DNA and RNA, and other distinguishing characteristics, are immunochemically related to Neurospora endo-exonuclease. The evidence indicates that these enzymes are derived from one or more related large, inactive (precursor?) polypeptides that are first converted to 75- to 80-kdalton active polypeptide(s) which are very protease sensitive. Further limited proteolysis results in the production of the various active forms of nuclease studied here. Some proteolytic conversions may occur in a controlled manner in vivo in different cell compartments, but others are very likely artifacts resulting from uncontrolled proteolysis during extraction and isolation. The intracellular forms of Neurospora endo-exonuclease are immunologically cross-active with ss-DNA-binding nucleases isolated from Aspergillus nidulans and Saccharomyces cerevisiae. They are not immunochemically related to two extracellular Neurospora nucleases, the pancreatic DNase-I-like DNase A and a ss-specific exonuclease, and they are also not related to other fungal and plant nucleases with ss-specific endonuclease activity such as the S1 nuclease of Aspergillus oryzae, the P1 nuclease of Penicillium citrinum, and mung bean nuclease.
mesh_terms: D000906:Antibodies; D000936:Antigen-Antibody Complex; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D004720:Endonucleases / Q000032:analysis*; D005092:Exonucleases / Q000032:analysis*; D007118:Immunoassay; D008970:Molecular Weight; D009491:Neurospora / Q000201:enzymology*; D009492:Neurospora crassa / Q000201:enzymology*
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D004720:Endonucleases; D005092:Exonucleases; C020104:endoexonuclease