The characterization of N-acetylglucosaminidases from the limpet Patella vulgata (L.)

The α- and β-N-acetylglucosaminidase activity of the limpet Patella vulgata (L.) is due to two enzymes. One of these enzymes hydrolyses both α- and β-N-acetylglucosaminidases and is referred to α,β-N-acetylglucosaminidase. The other is a β-N-acetylglucosaminidase (EC 3.2.1.30). Both enzymes have been isolated and characterized as glycoproteins containing 12% hexose, mainly galactose. The amino acid, neutral sugar and amino sugar content of the two enzymes is very similar, and the main difference lies in the presence of 9% sialic acid in β-N-acetylglucosaminidase. The molecular weight of α,β-N-acetylglucosaminidase is 217 000 and that of β-N-acetylglucosaminidase is 136 000. Evidence has been obtained for the presence of an additional sub-unit in the α,β-enzyme.