title: Small-molecule-substrate interactions with a self-aminoacylating ribozyme.
abstract: A self-aminoacylating RNA catalyst is shown to carry out the chemistry required for turnover, being reacylated several times from aminoacyl-AMP with an unaltered rate, thereby meeting one definition of an enzyme. Furthermore, a newly applied gel electrophoresis assay suggests first order kinetics in RNA and saturation kinetics in the substrate aminoacyl-adenylate, implying a Michaelis complex. AMP is a competitive inhibitor, though phenylalanine is not detectably inhibitory, consistent with a Michaelis complex through the AMP moiety of phenylalanyl-adenylate substrate. This idea is supported by measurement of elevated acylation velocities with seryl and alanyl-adenylates. The rate of aminoacylation increases with pH, consistent with attack of a terminal ribose oxyanion on the carbonyl carbon atom of the adenylate.
authors.affiliation: Department of MCD Biology, University of Colorado, Boulder 80309-0347, USA.
authors.forename: M
authors.initials: M
authors.lastname: Illangasekare
authors.forename: M
authors.initials: M
authors.lastname: Yarus
mesh_terms: D000215:Acylation; D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D000596:Amino Acids / Q000737:chemistry*; D002384:Catalysis; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D016337:RNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D016337:RNA, Catalytic; D000249:Adenosine Monophosphate; D012965:Sodium Chloride; C017620:phenylalanyl-5'-AMP