2ALecture 14

1 inimamon mechanism of translation wait a sec whats

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Unformatted text preview: es? “Ribozymes” are enzymes in which the catalysis is performed by RNA, rather than protein. The pepMdyl transferase funcMon of ribosomes is performed by an RNA. There are several other ribozymes, all with funcMons related to RNA metabolism. Hmmmm.. Was early life RNA ­based (no proteins, no translaMon)? +mRNA PA small subunit A = aminoacyl tRNA binding site P = peptidyl tRNA binding site Close-up of peptide bond formation Loss of a proton from the amino group . . . . 1. IniMaMon Mechanism of translation Wait a sec ­ what’s this E thing? It’s the site from which the empty tRNA is ejected. Don’t worry about it ­ we won’t discuss it. Close-up of peptide bond formation Note proteins are made from N to C Close-up of peptide bond formation leaves electrons ready to attack! NH3+ R1 O CH C O R2 O NH2 + H+ CH C O vulnerable carbon atom. Aminoacyl site Peptidyl site 4 2/9/10 Close-up of peptide bond formation Close-up of peptide bond formation linking the two amino acids electrons begin their attack Close-up of peptide bond formation creating a peptide bond. •  Elongation peptide bond NH3+ R2 O CH C O GGG •  Elongation •  Elongation NH3+ R1 O CH C NH HO R2 O CH C O R2 O HO R1 O NH3+ CH C NH CH C O U AC U AC G GG G A A G AU G C C C G C G U U C U A G A A U C P G GG G A A G AU G C C C G C G U U C U A G A A U C The used tRNA leaves the P site. P site empty 5 2/9/10 •  Elon...
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