Studies on the Thermodenaturation Behavior of Bacillus subtilis α‐Amylase on Chromatographic Media

The thermodenaturation behavior of Bacillus subtilis α‐amylase on some chromatographic media was studied by determining their adsorption parameters with frontal analysis. The experimental results show that on a RP‐C₁₈ reversed‐phase medium, a Chelating Sepharose Fast‐Flow chelated by Zn²⁺ affinity medium and a WCX‐1 cation‐exchange medium, a stable conformation of α‐amylase molecule separately exists below or over 30 °C; while on a PEG‐400 hydrophobic medium and a modified PEG‐400 medium, a stable conformation of α‐amylase molecule separately exists below 40 and 30 °C, and when the experimental temperatures are separately over 40 and 30 °C, a drastically conformational change of α‐amylase molecules can continuously take place. And by combining the intrinsic fluorescence emission spectrum and thermal inactivation profile of α‐amylase in free solution and on the PEG‐400 and modified PEG‐400 hydrophobic media, it can be concluded that in liquid chromatographic procedure, chromatographic media can induce the conformational change of α‐amylase molecules and promote their thermodenaturation; and in hydrophobic interaction chromatography, the higher the hydrophobicity of chromatographic medium, the lower the conformational change temperature of α‐amylase molecules on the chromatographic medium.