Puromycin analog, synthesis

The synthesis of this chemically reactive puromycin analog is relatively simple. Since iodoacylated puromycin is not very stable, a simple and rapid isolation procedure by DEAE-column chromatography was devised. 

Other antibiotics inhibit protein synthesis on all ribosomes (puromycin) or only on those of eukaryotic cells (cycloheximide). Puromycin (Figure 38—11) is a structural analog of tyrosinyl-tRNA. Puromycin is incorporated via the A site on the ribosome into the carboxyl terminal position of a peptide but causes the premature release of the polypeptide. Puromycin, as a tyrosinyl-tRNA analog, effectively inhibits protein synthesis in both prokaryotes and eukaryotes. Cycloheximide inhibits peptidyltransferase in the 60S ribosomal subunit in eukaryotes, presumably by binding to an rRNA component. 

Table 29.4). For example, the antibioticpuromycin inhibits protein synthesis by causing nascent prokaryotic polypeptide chains to be released before their synthesis is completed. Puromycin is an analog of the terminal aminoacyl-adenosine part of aminoacyl-tRNA (Figure 29.34). 

Puromycin is a specific metabolic inhibitor of protein synthesis and acts as an aminoacyl-tRNA analog and peptidyl acceptor. The latter causes premature chain... 

The protein synthesis inhibitors tetracycline, chloramphenicol, and streptomycin all block bacterial protein synthesis. Several eukaryotic translational inhibitors have also been found and they include diphtheria toxin, ricin, and cycloheximide. Puromycin causes premature chain termination in both prokaryotes and eukaryotes by functioning as an aminoacyl tRNA analog. 

As a general rule, if the natural ligand is aromatic, it seems advisable first to irradiate the natural ligand receptor complex before embarking on the synthesis of a pbotolabile analog. It has been found in a few cases, e.g., with puromycin or with iV -butyTyl-cAMP, that the chromophore... 

Puromycin has a structure closely analogous to the 3 terminus of a tyrosine-tRNA, and it inhibits protein synthesis by accepting, in place of an aminoacyl-tRNA, an incomplete polypeptide chain from ribosome-bound peptidyl-tRNA, thus prematurely terminating protein synthesis. We have found that irradiation at 2537 A (low-pressure Hg lamp) of solutions containing puromycin and ribosomes from E. coli leads to significant covalent incorporation of puromycin into the ribosome. For... 

Nemoto et al. developed a method for the fluorescence labeling of the C-terminal of nascent proteins using fluorescein-puromycin conjugates." The fluorescent analog of puromydn (an antibiotic that inhibits protein synthesis by binding to the A site on the ribosome) forms a bond with the C-terminal amino acid residue of the protein but only when the coding sequence does not contain a termination... 

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