Discusstion section 0519

Discusstion section 0519 - Discusstion section #7 1st step:...

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Unformatted text preview: Discusstion section #7 1st step: activate amino acid 2nd step: reacts with tRNA to form aminoacyl tRNA Mediated by Aminoacyl-tRNA Synthetases REACTIONS amino acid + ATP aminoacyl-AMP + PPi aminoacyl-AMP + tRNA aminoacyl-tRNA + AMP An amino-acid-specific enzyme appends the amino acid to the 3ribose residue of its cognate tRNA to form amino-acyl-tRNA Aminoacyl-tRNA Synthetases 2 c la s s e s : s truc tura l diffe re nc e s a ntic o do n re c o g nitio n: m a ny c la s s I do , m a ny c la s s II wo nt 2-O H vs . 3-O H a m ino a c id s pe c ific ity b inds tRNA fro m the m ino r g ro o ve o f a c c e pto r s te m b e nds it ha irpin a t 3 e nd b inds tRNA fro m the m a jo r g ro o ve o f a c c e pto r s te m 3 c o ntinue s in he lic a l pa th Different stereo chemistries for class I and II result in different OH groups being amino-acylated monomer some deep pockets Glutaminyl-tRNA synthetase (GlnRS) with tRNA Gln + ATP class I monomer class II enzyme dimer with two tRNA Asp Dimer or tetramer Ribosome A RNA-protein complex b inds m RNA b ring s in tRNA A a m ino ac yl s ite - inc o m ing c harg e d tRNA P pe ptidyl s ite - pe ptide bo nd fo rm a tio n E e xit s ite - e xiting dis c harg e d tRNA s upe rvis e s a nd pro o fre a ds b a s e -pa iring c a ta lyze s pe ptide b o nd fo rm a tio n unde rg o e s m o ve m e nt a llo ws tra ns la tio n re g ula tio n fa c to rs to re g ula te initia tio n, e lo ng a tio n, a nd te rm ina tio n Prokaryotic ribosome Eukaryotic ribosome 30s & 50s 40s & 60s Protein synthesis Occurs from N to C: Peptidyl transferase activity appends incoming aa to C- terminus Ribosomes read mRNA in 5 to 3 direction polysomes occur in 5 end polypeptide grows by being transferred from one tRNA to the next High salt treatment releases peptide chain from ribosome: C-terminal residue of the polypeptide is esterified to the peptidyl tRNA polypeptide grows by being transferred...
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This note was uploaded on 10/30/2010 for the course CHEM 114C taught by Professor Alexanderhoffmann during the Spring '08 term at UCSD.

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Discusstion section 0519 - Discusstion section #7 1st step:...

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