Question

3. (4 pts) Puromycin is an antibiotic that has an effect on both prokaryotes and eukaryotes. The drug, which is structurally similar to the aminoacyl terminus of an aminoacyl-tRNA (see figure below), inhibits protein synthesis by releasing nascent polypeptide chains before their synthesis is completed. н,с CH NH2 N N N CH CH HC нс. N N O 'N HOCH 0 R-O-POCHO H H 0 H H H H H H HAN OH O OH CO C=0 H-C-CH2 OCH H-C-R NH NH2 Puromycin Aminoacyl-tRNA Explain how puromycin can have this effect on growing polypeptide chains during translation (specifically, where does it reside within the ribosome) and why the peptide chains would be prematurely released.

Answer 1

hath 24 than an Puromycin mhibit translation gt is gt ind peptidyl transferase inhibitor Structura analogue of the 3' end of amino acyl transfer RNA but differ from tRNA in so far as aminoacyl whesidue is linked to the ribose via amide bond ester bond, Pusomycin bind to the Asite of Ribosome peptidyl transferase Center when occupied with it peptidy transferase links the ribosomal peptidyl tRNA Covalently to puxomycin to Puromycin. So amide bond by further peptidyl transfer take place Peptidyl -busomycin complex falls off the cribosome A site get þebtide presidues of e site in the cleaned ribosome no that cannot be CS Scanned with CamScanner

for Cu3 CH3 eg ERNA - phenylalanine ERHA N o P-0-C OHC O OH estesy bond C=0 Amide NH 04 Bond CCO H₂N-C-H H₂N-C-H CH2 CH2 tRNA phenylalanine O CHI Puromycin 9t donot cleaved. CS Scanned with CamScanner