InterPro: IPR000933 Glycoside hydrolase, family 29

O-Glycosyl hydrolases EC:3.2.1. are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [1, 2, 3]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site [4]. Because the fold of proteins is better conserved than their sequences, some of the families can be grouped in clans.

Family 29 (GH29) encompasses alpha-L-fucosidases (EC:3.2.1.51) [5], which is a lysosomal enzyme responsible for hydrolyzing the alpha-1,6-linked fucose joined to the reducing-end N-acetylglucosamine of the carbohydrate moieties of glycoproteins. Alpha-L-fucosidase is responsible for hydrolysing the alpha-1,6-linked fucose joined to the reducing-end N-acetylglucosamine of the carbohydrate moieties of glycoproteins.

Fucosylated glycoconjugates are involved in numerous biological events, making alpha-l-fucosidases, the enzymes responsible for their processing, critically important. Deficiency in alpha-l-fucosidase activity is associated with fucosidosis, a lysosomal storage disorder characterised by rapid neurodegeneration, resulting in severe mental and motor deterioration [6]. The enzyme is a hexamer and displays a two-domain fold, composed of a catalytic (beta/alpha)(8)-like domain and a C-terminal beta-sandwich domain [6].

Drosophila melanogaster spermatozoa contains an alpha-l-fucosidase that might be involved in fertilisation by interacting with alpha-l-fucose residues on the micropyle of the eggshell [7]. In human sperm, membrane-associated alpha-l-fucosidase is stable for extended periods of time, which is made possible by membrane domains and compartmentalisation. These help preserve protein integrity [8].