... almost continuous densityfor the < /b> backbone of < /b> CBH IB. The < /b> final model, 1Q9H,included 430 of < /b> the < /b> 437 amino acid residues of < /b> CBH IB. The< /b> final two amino acids and the < /b> loop region (from amino acids193–197) ... perhapsindicative of < /b> its flexibility. It is worth noting that the< /b> structures of < /b> T. re esei GH7 CBHs were solved in the < /b> presence of < /b> substrates. However, as 1Q9H was solved in the < /b> absence of< /b> bound substrate, ... deletion of < /b> these three residues, thus leading to a more open substrate-binding site.Catalytic binding siteBrooks et al . showed, by NMR, that the < /b> CBHs I fromT. emersonii has a retaining mechanism...