Ethylenediaminetetraacetic acid enhances structural stability and thermotolerance of recombinant cyclomaltodextrinase from Geobacillus thermopakistaniensis at higher temperatures

Ethylenediaminetetraacetic acid (EDTA), a chelating agent, has shown the ability to enhance the thermostability of cyclomaltodextrinase from Geobacillus thermopakistaniensis (CDase(Gt)). There was a 5-fold and 3-fold enhancement in the half-life of the enzyme at 70 and 75 degree celsius, respectively, when purified in the presence of EDTA. To further investigate, recombinant CDaseGt was subjected to molecular-level characterization using various techniques including circular dichroism spectroscopy, fluorescence spectroscopy, and fourier-transform infrared spectroscopy in the presence and absence of EDTA. Presence of EDTA caused several changes in the secondary structure of CDaseGt, specifically in terms of chirality and relocation of hydrophobic patches. No evident disturbance in the amino acid functional groups was observed with the addition of EDTA. In silico affinity analysis displayed favorable binding and attractive electrostatic interactions between CDase(Gt) and EDTA. These findings enhance our understanding about CDase(Gt)-EDTA interactions, and provide insights for developing efficient and stable enzymes with broad practical applications.