What kind of catalyst is peptidyl transferase, and where does it sit?

1. Peptidyl transferase catalyses the formation of each peptide bond. 2. It is an RNA-based enzyme rather than a protein one, which is why some ribosomal RNA is described as catalytic. 3. It is integrated into the 50S ribosomal subunit of the bacterial ribosome. 4. The 50S subunit is also the one carrying the A, P and E compartments, so the chemistry happens where the tRNAs are held. 5. Placing the enzyme in the 30S subunit puts it with the mRNA binding job instead. 6. Calling it a protein enzyme misses the point that ribosomal RNA itself does the catalysis. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 15 "Genes and Proteins", section 15.5 Ribosomes and Protein Synthesis_