title: Partial characterization of ribonuclease (RNase) activity from the isolated and solubilized brush border of Hymenolepis diminuta.
abstract: The isolated brush border membrane of Hymenolepis diminuta contained ribonuclease (RNase) activity which was demonstrable using yeast RNA or synthetic homopolymers of adenylic, cytidylic, inosinic, or uridylic acids as substrates. Polyguanylic acid was not hydrolyzed by worm RNase. RNase activity was inhibited by EDTA and divalent cations as well as sulfhydryl blocking and reducing agents. Polyguanylic acid and DNA were also inhibitors of RNase activity; these compounds were not hydrolyzed, but inhibited the hydrolysis of other substrates, possibly by nonproductive substrate binding. Data suggested that RNase (endonuclease) was probably the major enzyme activity in the degradation of long chain polyribonucleotides at the work's surface, while phosphodiesterase (exonuclease) activity did not contribute significantly to the hydrolysis of these compounds.
mesh_terms: D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006926:Hymenolepis / Q000201:enzymology*; D007700:Kinetics; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D011119:Polynucleotides / Q000378:metabolism; D012260:Ribonucleases / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D002413:Cations, Divalent; D011119:Polynucleotides; D004492:Edetic Acid; D012260:Ribonucleases; D010727:Phosphoric Diester Hydrolases