The predicted unfolding order of the β-strands in the starch binding domain from Aspergillus niger glucoamylase

The unfolding of the β-strands in the starch binding domain from Aspergillus niger glucoamylase was predicted to follow the order of β3→β2→β6→β5→β4→β1→β7 by 600 ps molecular dynamics simulations at 300, 400, and 600 K. The interior region around β-strands 2 and 3 acts as the initiation site for unfolding. β-Strands 1 and 7 are probably stabilized by the disulfide bond formed between Cys509 and Cys604. β-Strand 4 is stabilized by forming an antiparallel β-sheet with β-strand 1. Hydrophobic and electrostatic interactions between side chains instead of the hydrogen bonds are important in stabilizing these β-strands, thus the entire starch binding domain.