title: Purification and mode of action of exoribonuclease from bovine brain.
abstract: The exoribonuclease in bovine brain has been purified about 900-fold in 10% yield. The molecular weight is about 65,000. The enzyme is free from other ribonucleases of bovine brain. Studies of the mode of action of the enzyme show the following: (a) The enzyme cleaves both oligo- and polyribonucleotides exonucleolytically, initiating nucleolytic attack from the 5'-hydroxyl end to yield 3'-mononucleotides. The enzyme differs from spleen exonuclease in that it does not act on polydeoxyribonucleotides. (b) When the 5'-hydroxyl group is phosphorylated, the enzyme is inactive. (c) The enzymic action is processive in nature; the enzyme hydrolyzes one polynucleotide chain to completion before proceeding to the degradation of another chain.
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D005092:Exonucleases / Q000302:isolation & purification* / Q000378:metabolism; D009843:Oligoribonucleotides / Q000378:metabolism; D011061:Poly A / Q000378:metabolism; D012260:Ribonucleases / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D009843:Oligoribonucleotides; D011061:Poly A; D005092:Exonucleases; D012260:Ribonucleases