In a variant of chymotrypsin, Asp 102 is replaced by Glu 102. Do you expect the enzyme to retain activity? Schematically indicate the role of amino acid residues participating in catalysis.
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Answer:
The enzyme TEV protease[a] contains an example of a catalytic triad of residues (red) in its active site. The triad consists of an aspartate (acid), histidine (base) and serine (nucleophile). The substrate (black) is bound by the binding site to orient it next to the triad. (PDB: 1LVM)
A catalytic triad is a set of three coordinated amino acids that can be found in the active site of some enzymes.[1][2] Catalytic triads are most commonly found in hydrolase and transferase enzymes (e.g. proteases, amidases, esterases, acylases, lipases and β-lactamases). An Acid-Base-Nucleophile triad is a common motif for generating a nucleophilic residue for covalent catalysis. The residues form a charge-relay network to polarise and activate the nucleophile, which attacks the substrate, forming a covalent intermediate which is then hydrolysed to release the product and regenerate free enzyme. The nucleophile is most commonly a serine or cysteine amino acid, but occasionally threonine or even selenocysteine. The 3D structure of the enzyme brings together the triad residues in a precise orientation, even though they may be far apart in the sequence (primary structure).[3]