title: Purification from normal human plasma and biochemical characterization of a ribonuclease specific for poly(C) and poly(U).
abstract: A new specific ribonuclease from normal human plasma has been purified to homogeneity, following a five-step purification protocol that included DEAE-Sepharose, CM-Sepharose, and Heparin-Sepharose chromatographies. The purified enzyme was found to be glycosylated and appeared as a single 25-kDa band on a SDS polyacrylamide gel. This RNase is poly(C) preferential, degrading poly(U) at a lower rate. Activity of this RNase toward cleavage of native substrates such as ribosomal RNA was also detected. The human plasma ribonuclease is a thermolabile molecule, exhibiting maximum activity at pH 6.5. Comparison between other known plasma RNases and the human plasma ribonuclease described here indicated a variety of differences in their biochemical and catalytic properties.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Athens, Panepistimioupolis, Greece.
authors.forename: Irini D
authors.initials: ID
authors.lastname: Leimoni
authors.forename: Diamantis C
authors.initials: DC
authors.lastname: Sideris
authors.forename: Emmanuel G
authors.initials: EG
authors.lastname: Fragoulis
mesh_terms: D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D002417:Cattle; D002847:Chromatography, Agarose; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007700:Kinetics; D011066:Poly C / Q000378:metabolism*; D011072:Poly U / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000378:metabolism; D051381:Rats; D012259:Ribonuclease, Pancreatic / Q000037:antagonists & inhibitors / Q000378:metabolism; D012260:Ribonucleases / Q000097:blood* / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D002413:Cations, Divalent; D004791:Enzyme Inhibitors; D012335:RNA, Ribosomal; D011072:Poly U; D011066:Poly C; D012260:Ribonucleases; D012259:Ribonuclease, Pancreatic