title: Endoribonuclease from bovine adrenal cortex cytosol.
abstract: An endoribonuclease which digests a variety of synthetic homoribopolymers and poly(A)-rich mRNA has been identified and purified greater than 500-fold with respect to specific activity from bovine adrenal cortex cytosol. Enzymatic digestion of synthetic poly(riboadenylic acid) was stimulated by Mn-2+ and Mg-2+ and the enzyme exhibited broad pH and salt optima. Poly(cytidylic acid) and poly(uridylic acid), but not poly(guanylic acid), served as substrates for the enzyme preparation; double-stranded RNA, DNA, and DNA-RNA hybrids were not digested by the enzyme. Digestion generated oligonucleotides with 3-hydroxyl and 5'-monophosphoester termini. On isoelectric focusing, the enzymatic activity banded at pH 8.3 plus or minus 0.2. An initial preferential cleavage of the poly(A) tract of poly(A)-rich RNA is suggested by the rapid appearance of a 4-6S digestion product highly enriched for adenylic acid; however, progressive digestion of the RNA occurs with additional incubation.
mesh_terms: D000302:Adrenal Cortex / Q000201:enzymology*; D000311:Adrenal Glands / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D002501:Centrifugation, Zonal; D002848:Chromatography, DEAE-Cellulose; D003600:Cytosol / Q000201:enzymology; D004720:Endonucleases / Q000302:isolation & purification / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007525:Isoelectric Focusing; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology*; D008345:Manganese / Q000494:pharmacology; D009994:Osmolar Concentration; D012260:Ribonucleases / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D008345:Manganese; D004720:Endonucleases; D012260:Ribonucleases; D008274:Magnesium