Purification and properties of beta-N-acetylglucosaminidase from Mytilus edulis L. gonads

Abstract

beta-N-Acetylglucosaminidase (beta-2-acetamido-2-deoxy-D-glucoside acetamidodeoxyglucohydrolase EC 3.2.1.30) from Mytilus edulis gonads and a homogenous protein was obtained from it by ion-exchange chromatography, gel filtration and disc electrophoresis. The apparent molecular weight, determined by gel filtration was 140,000 +/- 5,000. Two subunits were identified. The molecular weights of both subunits calculated by disc-electrophoresis were 70,000 and 75,000 + 2,000. Maximal activity for pH was 4.2. At 50 degrees C the enzyme was still active; at 60 degrees C inactive. The values of the apparent Km's proved to be 0.57 mM and 0.076 mM for p-nitrophenyl-beta-D-N-acetylglucosaminide and p-nitrophenyl-beta-D-N-acetylgalactosaminide as substrates. In the incubation of the enzyme with hyaluronic acid, chitin, deacetilated glycol-chitin and p-nitrophenyl-beta-D-glucuronide, N-acetyl-beta-D-glucosamine and glucuronic acid were not liberated. N-acetylgluconolactone and N-acetylgalactonolactone are competitive inhibitors for the enzyme.