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Small-molecule-substrate interactions with a self-aminoacylating ribozyme
Small-molecule-substrate interactions with a self-aminoacylating ribozyme.
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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.
Illangasekare M, Yarus M
Journal of molecular biology
1997-05-09 00:00
268
3
631-9
Acylation,Adenosine Monophosphate,Amino Acids,Catalysis,Electrophoresis, Polyacrylamide Gel,Hydrogen-Ion Concentration,Kinetics,Molecular Sequence Data,Nucleic Acid Conformation,RNA, Catalytic,Sodium Chloride,Amino Acids,RNA, Catalytic,Adenosine Monophosphate,phenylalanyl-5'-AMP,Sodium Chloride
Department of MCD Biology, University of Colorado, Boulder 80309-0347, USA
J. Mol. Biol.
NIGMS GM48080
0022-2836
10.1006/jmbi.1997.0988
S0022-2836(97)90988-8
1468
True
9171286
