🔬biological chemistry i review

key term - Peptidyl transferase activity

Definition

Peptidyl transferase activity refers to the enzymatic function of forming peptide bonds between amino acids during protein synthesis, specifically during translation. This activity is primarily associated with the large subunit of the ribosome, where it catalyzes the reaction that links the carboxyl group of one amino acid to the amino group of another, thereby elongating the polypeptide chain. The precision and efficiency of this process are crucial for the accurate assembly of proteins based on mRNA templates.

5 Must Know Facts For Your Next Test

  1. Peptidyl transferase activity is primarily carried out by ribosomal RNA (rRNA) within the ribosome, specifically in the large subunit known as the 50S subunit in prokaryotes.
  2. The formation of peptide bonds is a condensation reaction, releasing a molecule of water as amino acids are linked together in a growing polypeptide chain.
  3. This activity is essential during the elongation phase of translation when tRNA molecules sequentially add their respective amino acids based on the codon sequence of mRNA.
  4. Inhibition of peptidyl transferase activity can lead to disruptions in protein synthesis and has been targeted by certain antibiotics to combat bacterial infections.
  5. Understanding peptidyl transferase activity is vital for molecular biology and biotechnology applications, including protein engineering and therapeutic development.

Review Questions

  • How does peptidyl transferase activity contribute to the overall process of translation?
    • Peptidyl transferase activity plays a central role in translation by catalyzing the formation of peptide bonds between adjacent amino acids as they are added to the growing polypeptide chain. This enzymatic function occurs in the ribosome during the elongation phase, where tRNA molecules bring specific amino acids that correspond to the codons in mRNA. By facilitating these reactions efficiently, peptidyl transferase ensures that proteins are synthesized accurately according to genetic instructions.
  • Discuss how the structure of the ribosome facilitates peptidyl transferase activity during protein synthesis.
    • The structure of the ribosome is intricately designed to facilitate peptidyl transferase activity. The large subunit contains rRNA that serves as the catalytic core for peptide bond formation. The ribosome has distinct sites (A, P, and E sites) where tRNA molecules bind; the P site holds the growing polypeptide chain, while the A site brings in new tRNA with its respective amino acid. This arrangement allows for efficient positioning and alignment necessary for catalysis, making peptidyl transferase activity a seamless part of translation.
  • Evaluate the implications of targeting peptidyl transferase activity in antibiotic development and how it affects bacterial protein synthesis.
    • Targeting peptidyl transferase activity in antibiotic development has significant implications for treating bacterial infections. Antibiotics like chloramphenicol inhibit this enzymatic function within bacterial ribosomes, disrupting protein synthesis. This selective inhibition allows for effective treatment while sparing human cells since eukaryotic ribosomes differ structurally. The ability to inhibit bacterial protein synthesis through this mechanism highlights how understanding peptidyl transferase activity is crucial for developing novel antimicrobial strategies and combating resistance.

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