DOMON-like type 9 carbohydrate binding module. Family 9 carbohydrate-binding modules (CBM9) play a role in the microbial degradation of cellulose and hemicellulose (materials found in plants). The domain has previously been called cellulose-binding domain. The polysaccharide binding sites of CBMs with available 3D structure have been found to be either flat surfaces with interactions formed by predominantly aromatic residues (tryptophan and tyrosine), or extended shallow grooves. CBM9 domains found in this uncharacterized heterogeneous subfamily are often located at the C-terminus of longer proteins and may co-occur with various other domains.
Carbohydrate family 9 binding domain-like. CBM9_1 is a C-terminal domain on bacterial xylanase proteins, and it is tandemly repeated in a number of family-members. The CBM9 module binds to amorphous and crystalline cellulose and a range of soluble di- and monosaccharides as well as to cello- and xylo- oligomers of different degrees of polymerization. Comparison of the glucose and cellobiose complexes during crystallisation reveals surprising differences in binding of these two substrates by CBM9-2. Cellobiose was found to bind in a distinct orientation from glucose, while still maintaining optimal stacking and electrostatic interactions with the reducing end sugar.
NPCBM-associated, NEW3 domain of alpha-galactosidase. The English-language version of the first reference can be found on pages 388-399 of the above. This domain has been named NEW3 but its actual function is not known. It is found on proteins which are bacterial galactosidases. The domain is associated with the NPCBM family, pfam08305, a novel putative carbohydrate binding module found at the N-terminus of glycosyl hydrolases.