Evolution acts via mutations in amino acid sequences. Substitution of essential amino acids leads to a nonfunctional protein. Thus, the number of essential residues is limited by evolutionary... Show moreEvolution acts via mutations in amino acid sequences. Substitution of essential amino acids leads to a nonfunctional protein. Thus, the number of essential residues is limited by evolutionary pressure. The roles of all non-catalytic essential residues in class A β-lactamases are described with a large-scale experiments, as well as specific functions of a few residues. The results show that residues close to the active site and farther away have different reasons for being essential. Show less
