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„Y Amino acid activation site, serving as the ¡§coarse sieve¡¨, contains Pro46, Trp518,Trp558 which corresponding to van der Waals interactions with side chain and Asp58,Gln554 which forming H-bond with the NH3+ and COO- groups.
„Y The ¡§fine sieve¡¨, serving for editing, made up of Tyr386, His384, Trp232 and Phe359 is just large enough to accommodate L-valine. This site was further confirmed by mutagenesis analysis.
„Y The fine sieve may function as the catalytic triads of hydrolases when hydrolyzing Val-AMP and Val-tRNAIle.
„Y The ATP consumption demonstrates the high cost of accuracy.