5-Enzyme mechamism handout2

Lehninger 4th ed 12 rnase acidbase catalysis 2 base

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Unformatted text preview: charge,anucleophile.averystrongnucleophile RNase: acid/base catalysis 2. Base forms a strong nucleophile (RO-) withcatalysis,alsotransitionstate catalysis:isthisdifferentfromnon-catalytic transitionstate-morestable?lessstable? Transition state #1 RNase: acid/base catalysis 2. Base forms a strong nucleophile (RO-) a) His-12 deprotonates the 2’-hydroxyl group of the pyrimidine nucleotide residue. b) The resulting nucleophilic oxygen atom attacks the adjacent elctrophile (P), forming a new P-O bond. c) His-119 acts as an acid and donates a proton to the other oxygen to neutralize the charge. Lehninger 4th ed. 12 RNase: acid/base catalysis 2. Base forms a strong nucleophile (RO-) Uncatalyzed – without enzyme Catalyzed – with enzyme RNase: acid/base catalysis 3. Acid forms a better leaving group (ROH) RO...
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This note was uploaded on 04/01/2014 for the course BIOL 201 taught by Professor Chowrira during the Winter '13 term at UBC.

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