Showing papers by "Tokyo University of Science published in 1976"

Multiple Forms of Nuclear Ribonuclease H from Tetrahymena pyriformis

Abstract: Three types of ribonuclease H were detected in the isolated macronuclei of Tetrahymena pyriformis GL, partially purified and characterized. They were eluted at around 0.15 M, 0.3 M and 0.4 M of ammonium chloride in phosphocellulose chromatography, and termed H-1, H-2 and 11-3, respectively. The partially purified enzymes have following properties. a) These enzymes specifically hydrolyze the RNA moiety of RNA. DNA hybrid. Neither DNA moiety of'RNA. DNA hybrid nor the RNA molecule dissociated by heat from RNA. DNA hybrid is hydrolyzed by these enzymes. b) The enzymes are most active at pH 8.5-9.0. c) They require divalent cations such as Mg2+ Or Mn2+ for their activities. The optimal concentrations of these cations are different among these enzymes. d) The mode of cleavage by these enzymes is endonucleolytic, producing mostly oligonucleotides and a small amount of mononueleotIdes which possess 3′-hydroxyl and 5′-phosphate termini.