background: tay-sachs disease (tsd), or gm2 gangliosidosis, is a lethal autosomal recessive neurodegenerative disorder, which is caused by a deficiency of beta-hexosaminidase a (hexa), resulting in lysosomal accumulation of gm2 ganglioside. the aim of this study was to identify the tsd-causing mutations in an iranian population. methods: in this study, we examined 31 patients for tsd-causing mu...

Human kidney hexosaminidase A (beta-N-acetylglucosaminidase; 2-acetamido-2-deoxy-beta-D-glucoside acetamidodeoxyglucohydrolase; EC 3.2.1.30) is a heteropolymer of two immunologically distinct subunits designated as alpha and beta. Hexosaminidase B, however, is a homopolymer comprised entirely of beta subunits. When human kidney hexosaminidase A was dissociated into its subunits by p-hydroxymerc...

The activity of purified human hexosaminidases A and B toward hyaluronic acid (HA) isolated from cultured hum& skin fibroblasts was investigated. The cleavage of N-acetylglucosaminyl residues to monosaccharide N-acetylglucosamines by hexosaminidase isozymes was determined in the presence and absence of purified human fi-glucuronidase. The pH optima of this reaction, with and without P-glucuroni...

A crude /I-hexosaminidase fraction prepared by (NH,),SO( fractionation of human liver extract or urine was found to convert Tay-Sachs ganglioside, GalNAcPl -+ 4(NANcrZ -+ 3)Gal/31 --f 4Glc + ceramide (G& into NAN& + 3Galfil -+ 4 Glc + ceramide (GMM3). After separation of hexosaminidase A and B by DEAE-cellulose chromatography, only freshly prepared fi-hexosaminidase A hydrolyzed GM2 although bo...

from case 2, however, showed a shoulder at pH4.5 due probably to some residual glucosaminidase A and glucosaminidase B activity. The optimum for both glucosaminidase and galactosaminidase activities ofleucocytes from this patient was pH4.5; here a greater proportion of hexosaminidase A and hexosaminidase B remains, masking the C form. The total hexosaminidase activity of these leucocytes was 4 ...

Hexosaminidase A is present in relatively low concentrations in cell-free amniotic fluids from pregnancies with Tay-Sachs fetuses. This isoenzyme was determined by an immunological procedure, radial immunodiffusion, by which hexosaminidase A can be directly and specifically detected, even in the presence of excess amounts of hexosaminidase B. No hexosaminidase A could be detected by the same pr...

Liver biopsies from 88 patients with different liver diseases were studied for beta-hexosaminidase activity. Liver specimens with normal light microscopical morphology showed no immunohistochemical reactivity for beta-hexosaminidase. Increased reactions were noted, mainly in hepatocytes, in biopsies from the patients with different liver diseases. A very large interindividual variation of bioch...

b-Hexosaminidase, which is generally present in the lysosome, is essential for glycoprotein metabolism in the maintenance of cell homeostasis. In mast cells (MCs), large amounts of b-hexosaminidase are present in the granules as opposed to the lysosome, and the biological role of MC b-hexosaminidase has yet to be fully elucidated. Therefore, we investigated the biological role of b-hexosaminida...

Previous studies of the subunit structure of hexosaminidase gave ambiguous results, but suggested that the enzyme was composed of six equally sized subunits. Dissociation of hexosaminidase A with p-chloromercuribenzoate produces an alkylated fragment with mol.wt. approx. 50000, which is converted into hexosaminidase S by treatment with dithiothreitol. Treatment ofnative hexosaminidase A with so...

The techniques of somatic cell genetics have been used to establish the linkage relationships of loci coding for two forms (A and B) of hexosaminidase (EC 3.2.1.30; 2-acetamido-2-deoxy-beta-D-glucoside acetamidodeoxyglucohydrolase) and to determine whether a structural relationship exists between these forms. In a series of human-mouse hybrid cell lines, hexosaminidase A and B segregated indepe...