3.1. Interfacial interaction analysis
In an effort to redesign DAADH for improved stability, interfacial interactions of A and B subunits of DAADH from Ureibacillus thermosphaericus (DAwild) were analyzed by Protein Contacts Atlas. Amino acid residues interaction analysis indicated that there are only weak interfacial interactions between the A and B subunits, which are only one salt bridges and 12 hydrogen bonds. The salt bridge was form by GLU136 of A subunit and LYS316 of B subunit with the distance of 3.177 Å (Fig. 2A). Interactions heatmap of Helix 15 and 16 of A subunit and Helix 23 of B subunit were investigated and key residues were highlighted (Fig. 2B). Therefore, the interfacial interactions of subunits and motifs can be further improved to enhance the stability of the enzyme [23].