Hexosaminidase

Hexosaminidases are enzymes that cleave the terminal residues of N - Acetylglucosiden by hydrolysis, and degrade them step by step. This reaction is part of the degradation of glycosaminoglycans and glycosphingolipids in animals and chitin in plants and bacteria. In humans, five proteins with hexosaminidase activity are known to occur in several isoforms and assemble to form enzyme complexes. Mutations in the HEXA gene are the cause of Tay -Sachs disease, and mutations at the HEXB gene are responsible for Sandhoff disease.

The five hexosaminidases be called hexosaminidase A to D and S. Hexosaminidase A, B and S are protein complexes and both products of the two genes HEXA ( subunit α ) and HEXB ( subunits βA and βB ) are formed. The A enzyme is a trimer α - βA - βB, B enzyme is a tetramer - βA βA, βB βB, and - S- enzyme is a dimer of α - α. Last hexosaminidase C is the monomer of MGEA5 gene product, as well as the dimer of D HEXDC gene product.

Hexosaminidases form family 20 in the classification of glycosidases by Henrissat.