Studies on Active Sites of Ribosomes with Haloacetylated Antibiotic Analogs
The technique of affinity labeling allows the direct identification of the sites of interaction between two molecules, for example, between substrate and enzyme or, just as well, between a drug and its target. In general, a chemically reactive group is introduced into a molecule, which then can react preferentially and irreversibly with a properly oriented amino acid functional group in the binding region of the protein(s). We applied this technique to the antibiotics chloramphenicol, puromycin and streptomycin in order to find out, which ribosomal protein is associated with the binding sites of these antibiotics. All three antibiotics were modified with bromoor iodoacetic acid such that they did not lose their known antibiotic properties. However, the introduction of a haloacetyl group into the antibiotics leads to a chemical linkage between the antibiotic and its ribosomal binding site. The respective labeled ribosomal proteins were isolated and, thus, the ribosomal protein(s) involved in the binding of the antibiotic, could be identified.
KeywordsRibosomal Protein Ribosomal Subunit Acceptor Site Iodoacetic Acid Peptidyltransferase Center
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