The unfolding of the beta-strands in the starch binding domain from Aspergillus niger glucoamylase was predicted to follow the order of beta3 --> beta2 --> beta6 --> beta5 --> beta4 --> beta1 --> beta7 by 600 ps molecular dynamics simulations at 300, 400, and 600 K. The interior region around beta-strands 2 and 3 acts as the initiation site for unfolding. beta-Strands 1 and 7 are probably stabilized by the disulfide bond formed between Cys509 and Cys604. beta-Strand 4 is stabilized by forming an antiparallel beta-sheet with beta-strand 1. Hydrophobic and electrostatic interactions between side chains instead of the hydrogen bonds are important in stabilizing these beta-strands, thus the entire starch binding domain. (C) 2002 Elsevier Science B.V. All rights reserved.