title: Escherichia coli RNase D. Purification and structural characterization of a putative processing nuclease.
abstract: RNase D, a putative tRNa processing nuclease, has been purified about 1,000-fold from extracts of Escherichia coli to apparent homogeneity, as judged by acrylamide gel electrophoresis under nondenaturing and denaturing conditions and by gel electrofocusing. The purified enzyme is a single chain protein with a molecular weight of 40,000 and an isoelectric point of about 6.2. Spectral analysis indicated that RNase D is devoid of nucleic acid. Amino acid analysis suggested a low content of cysteine, and this was confirmed by the relative insensitivity of the enzyme to sulfhydryl group reagents. RNase D is sensitive to inactivation by elevated temperatures but can be protected by a variety of RNAs, including those which are not substrates for hydrolysis. The relation of RNase D to other known E. coli ribonucleases and to other previously identified processing activities, is discussed.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D004720:Endonucleases / Q000302:isolation & purification* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins; D008970:Molecular Weight; D043244:Ribonuclease III; D012260:Ribonucleases / Q000302:isolation & purification* / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D029968:Escherichia coli Proteins; D013439:Sulfhydryl Reagents; D004720:Endonucleases; D012260:Ribonucleases; D043244:Ribonuclease III; C468366:ribonuclease III, E coli