title: A fluorimetric enzyme assay for the diagnosis of Sanfilippo disease C (MPS III C).
abstract: Both the alpha- and beta-anomers of 4-methylumbelliferyl-D-glucosaminide were synthesized and shown to be substrates for the lysosomal acetyl-CoA:glucosaminide N-acetyltransferase. Using the beta-anomer, fibroblasts and leukocytes from 11 different Sanfilippo C patients showed < 1% of mean normal N-acetyltransferase activity. Heterozygotes showed intermediate activities. The enzymatic liberation of the fluorochrome from 4-methylumbelliferyl-beta-D-glucosaminide requires the sequential action of the N-acetyltransferase and beta-hexosaminidase. Normal beta-hexosaminidase activity caused complete hydrolysis of the reaction intermediate 4-methylumbelliferyl-beta-D-N-acetylglucosaminide formed by the N-acetyltransferase. In cell extracts with a beta-hexosaminidase deficiency, however, a second incubation in the presence of excess beta-hexosaminidase is needed to avoid underestimation of the N-acetyltransferase activity.
authors.affiliation: Institute of Biochemistry, Academy of Sciences Armenian Republic, Yerevan.
authors.lastname: Voznyi YaV
authors.forename: E A
authors.initials: EA
authors.lastname: Karpova
authors.forename: T V
authors.initials: TV
authors.lastname: Dudukina
authors.forename: I V
authors.initials: IV
authors.lastname: Tsvetkova
authors.forename: A M
authors.initials: AM
authors.lastname: Boer
authors.forename: H C
authors.initials: HC
authors.lastname: Janse
authors.forename: O P
authors.initials: OP
authors.lastname: van Diggelen
mesh_terms: D000123:Acetyltransferases / Q000172:deficiency / Q000378:metabolism*; D002478:Cells, Cultured; D005347:Fibroblasts / Q000201:enzymology; D005470:Fluorometry; D006579:Heterozygote; D006801:Humans; D006923:Hymecromone / Q000031:analogs & derivatives / Q000378:metabolism; D007962:Leukocytes / Q000201:enzymology; D009084:Mucopolysaccharidosis III / Q000175:diagnosis* / Q000201:enzymology; D012016:Reference Values
chemical_list: C008511:4-methylumbelliferyl-beta-glucosaminide; D006923:Hymecromone; D000123:Acetyltransferases; C020580:glucosamine acetyltransferase