beta-hexosaminidase, alpha-D-mannosidase, and beta-mannosidase expression in serum from patients with carbohydrate-deficient glycoprotein syndrome type I

The activity of beta -hexosaminidase, determined \Nith 4-methylumbelliferyl -beta -N-acetylglucopyranoside substrate, and of beta -D-mannosidase was si gnificantly higher in the serum of patients with carbohydrate-deficient gly coprotein (CDG) syndrome type IA (phosphomannomutase deficiency) than in co ntrols. No significant differences were observed in the activity of beta -h exosaminidase, determined using 4-methylumbelliferyl-beta -N-acetylglucopyr anoside-6-sulphate as substrate, and the activity of alpha -D-mannosidase. Using DEAE-cellulose chromatography, a greater amount of hexosaminidase B t han hexosaminidase A was detected in CDG serum. In CDG serum, hexosaminidas e A was eluted in a more basic position in the salt gradient. An isoenzyme of alpha -D-mannosidase and beta -D-mannosidase was identified in control a nd CDG sera. alpha -D-Mannosidase isoenzyme was eluted in a slightly more b asic position in CDG serum than in control serum, whereas beta -D-mannosida se isoenzyme was eluted in the same position. (C) 2000 Elsevier Science B.V . All rights reserved.