Structural determinants of cold adaptation and stability in a large protein

• Main Authors: Charles Gerday, Georges Feller
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2001
• Subjects: Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1027.1025; http://orbi.ulg.ac.be/bitstream/2268/16026/1/JBC_2001_MutAHA.pdf

The heat-labile a-amylase from an antarctic bacte-rium is the largest known protein that unfolds revers-ibly according to a two-state transition as shown by differential scanning calorimetry. Mutants of this en-zyme were produced, carrying additional weak interac-tions found in thermostable a-amylases. It is shown that single amino acid side chain substitutions can signifi-cantly modify the melting point Tm, the calorimetric enthalpy DHcal, the cooperativity and reversibility of unfolding, the thermal inactivation rate constant, and the kinetic parameters kcat and Km. The correlation be-tween thermal inactivation and unfolding reversibility displayed by the mutants also shows that stabilizing interactions increase the frequency of side reactions during refolding, leading to intramolecular mismatches