CHB HEX N-terminal domain

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CHB_HEX N-terminal domain
PDB 1c7t EBI.jpg
beta-n-acetylhexosaminidase mutant e540d complexed with di-n acetyl-d-glucosamine (chitobiase)
Symbol CHB_HEX
Pfam PF03173
Pfam clan CL0203
InterPro IPR004866
SCOP 1c7s

In molecular biology, the CHB HEX N-terminal domain represents the N-terminal domain in chitobiases and beta-hexosaminidases. Chitobiases degrade chitin, which forms the exoskeleton in insects and crustaceans, and which is one of the most abundant polysaccharides on earth.[1] Beta-hexosaminidases are composed of either a HexA/HexB heterodimer or a HexB homodimer, and can hydrolyse diverse substrates, including GM(2)-gangliosides; mutations in this enzyme are associated with Tay-Sachs disease.[2] HexB is structurally similar to chitobiase, consisting of a beta sandwich structure; this structure is similar to that found in the cellulose-binding domain of cellulase from Cellulomonas fimi.[1] This domain may function as a carbohydrate binding module.


  1. ^ a b Tews I, Perrakis A, Oppenheim A, Dauter Z, Wilson KS, Vorgias CE (July 1996). "Bacterial chitobiase structure provides insight into catalytic mechanism and the basis of Tay-Sachs disease". Nat. Struct. Biol. 3 (7): 638–48. doi:10.1038/nsb0796-638. PMID 8673609. 
  2. ^ Mark BL, Mahuran DJ, Cherney MM, Zhao D, Knapp S, James MN (April 2003). "Crystal structure of human beta-hexosaminidase B: understanding the molecular basis of Sandhoff and Tay-Sachs disease". J. Mol. Biol. 327 (5): 1093–109. doi:10.1016/S0022-2836(03)00216-X. PMC 2910754. PMID 12662933. 

This article incorporates text from the public domain Pfam and InterPro IPR004866