Homologous Alkalophilic and Acidophilic L-Arabinose Isomerases Reveal Region-Specific Contributions to the pH Dependence of Activity and Stability

Abstract
To study the pH dependence of L-arabinose isomerase (AI) activity and stability, we compared homologous AIs with their chimeras. This study demonstrated that an ionizable amino acid near the catalytic site determines the optimal pH (pHopt) for activity, whereas the N-terminal surface R residues play an important role in determining the pHopt for stability.