ORGN 878 |
| The leucyl, phenylalanyl-tRNA transferase of E. coli catalyzes the addition of the amino acid from a charged leucyl- or phenylalanyl-tRNA to an arginyl or lysyl N-terminal residue of a substrate protein. In vivo, this addition signals the degradation of the substrate protein through the N-end rule pathway. The relaxed specificity of the transferase can be exploited through the use of mutant aminoacyl-tRNA synthetases that charge tRNAs with non-canonical amino acids. The mis-charged tRNAs can act as amino acid donors for the transfer reaction. We have tested the activity of the transferase in vitro with a variety of non-canonical amino acids using a dipeptide-aminocoumarin substrate. p-Azidophenylalanine, p-cyanophenylalanine, p-ethynylphenylalanine, p-acetylphenylalanine, azidohomoalanine, homopropargylglycine, and oxonorvaline can all be utilized as aminoacyl-tRNA substrates by the L,F-transferase based on detection by HPLC and subsequent MALDI-TOF analysis. The steady-state kinetic parameters of the enzyme and individual amino acids are currently under investigation.
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Proteins, Peptides, Amino Acids, and Enzyme Inhibitors
8:00 AM-12:00 PM, Thursday, 14 September 2006 Moscone Center -- Room 131, Oral
Division of Organic Chemistry |
