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...

Abstraet--N-Acetyl-hexosaminidase (Hex) exists in various human tissues in two major isozymic forms--Hex A and Hex B. The main difference between the two forms is the lability of Hex A to both heat and acid as compared to the stability of Hex B. When heated to 50°C for 2-3 hr Hex A loses its entire enzymatic activity. In the present study we demonstrate that specific antiserum stabilizes Hex A ...

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...

In the assay for hexosaminidase A (Hex A) in leukocytes, cultured fibroblasts, and cultured amniotic fluid cells for the detection of Tay-Sachs disease and carrier identification, bovine serum albumin (BSA) is used (1,2). We find that some BSA preparations are contaminated with hexosaminidase activity. We wish to warn others of this and to show how an incorrect diagnosis could be reached by usi...

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...