InterPro domain: IPR000246

Threonine peptidases are characterised by a threonine nucleophile at the N terminus of the mature enzyme. The threonine peptidases belong to clan PB or are unassigned, clan T-. The type example for this clan is the archaean proteasome beta component of Thermoplasma acidophilum.

This group of sequences have a signature that places them in MEROPS peptidase family T2 (clan PB(T)). The glycosylasparaginases ( 3.5.1.26 ) are threonine peptidases. Also in this family is L-asparaginase ( 3.5.1.1 ), which catalyses the following reaction: L-asparagine + H ₂ O = L-aspartate + NH ₃

Glycosylasparaginase catalyses: N4-(beta-N-acetyl-D-glucosaminyl)-L-asparagine + H(2)O = N-acetyl-beta-glucosaminylamine + L-aspartate cleaving the GlcNAc-Asn bond that links oligosaccharides to asparagine in N-linked glycoproteins. The enzyme is composed of two non-identical alpha/beta subunits joined by strong non-covalent forces and has one glycosylation site located in the alpha subunit [ 1 ] and plays a major role in the degradation of glycoproteins.

1. Purification, biochemistry and molecular cloning of an insect glycosylasparaginase from Spodoptera frugiperda. Glycobiology 6, 527-36