puromycin uggest a likely relative order of bioactivity of these analogs and exp
ID: 213658 • Letter: P
Question
puromycin uggest a likely relative order of bioactivity of these analogs and explain your order briefly (3) Inside cells the molecule transfer RNA (RNA) (1) is a key ftactor synthesis. Its structure involves a long chain of an in protein adenosine nucleotide unit which is esterified at the 3-OH group of the terminated by e sugar ring. Puromycin (2) is a drug which blocks protein synthesis ony NT NH OH CH-NH2 CH-NH CH (a) Puromycin (2) is considered an isostere of transfer RNA (1). Eplain clearly why this so. (b) A nitrogen and oxygen in puromycin are methylated. How might th efffect the ability of the drug to be delivered to its target? (c) Suggest another isostere which might possibly be even more effe than puromycin. Extensions or modifications of the isostere concept are group reve and 'ring analogs" (a) Explain these concepts as they apply to structures (1) versus and (3) versus (4). (b) For (3) versus (4), what may be the advantage of (3) over4 of dosage of the drug likely required. Explain briefy.Explanation / Answer
Puromycin secondary metabolite of Streptomyces alboniger that blocks protein biosynthesis. Puromycin is a structural analogue of the 3 end of aminoacyl-transfer RNA, but differs from tRNA insofar as the aminoacyl residue is linked to the ribose via an amide bond rather than an ester bond. Puromycin, like aminoacyl-tRNA, binds to the A site of the ribosome peptidyl-transferase center. When the A site is occupied by puromycin, peptidyl-transferase links the peptide residues of the peptidyl-tRNA in the ribosomal P site covalently to puromycin. Since the amide bond cannot be cleaved by the ribosome, no further peptidyl transfer takes place, and the peptidyl-puromycin complex falls off the ribosome.
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