Peptidyl transferase

Peptidyl transferase is an enzyme that plays a crucial role in protein synthesis. It is located in the ribosome, specifically in the large subunit (50S in prokaryotes, 60S in eukaryotes). The function of peptidyl transferase is to catalyze the peptide bond formation between the amino acids during the translation process of protein synthesis.

Function

Peptidyl transferase catalyzes the formation of a peptide bond between the carboxyl group of the peptidyl-tRNA in the P site and the amino group of the aminoacyl-tRNA in the A site. This reaction is a condensation reaction, meaning it results in the release of a water molecule.

Structure

The peptidyl transferase center (PTC) is located in the large subunit of the ribosome. It is composed of ribosomal RNA (rRNA), not protein, which makes it a ribozyme. The PTC is highly conserved across all domains of life, indicating its fundamental importance in biology.

Mechanism

The exact mechanism of peptidyl transferase is still not fully understood. However, it is known that the reaction it catalyzes is a nucleophilic attack by the amino group of the aminoacyl-tRNA on the carbonyl carbon of the peptidyl-tRNA. This results in the formation of a peptide bond and the release of the deacylated tRNA.

Role in Antibiotic Resistance

Many antibiotics target the peptidyl transferase center of the ribosome, inhibiting protein synthesis and thus killing the bacteria. However, mutations in the PTC can lead to antibiotic resistance, a major problem in modern medicine.

See Also

• Protein biosynthesis
• Ribosome
• Translation (biology)
• Antibiotic resistance

References

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