Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GM1-ganglioside hydrolysis by leukocytes and fibroblasts, tissues easily obtainable from patients, was investigated using 3H-labeled GM1 and was found to be at least as active as that reported for any other tissue. Sodium taurocholate was required for the reaction, the crude bile salt at an optimum concentration of 0.4% producing twice as much activity as pure taurocholate at its optimum concentration of 0.8%. Leukocyte GM1-ganglioside beta-galactosidase and 4-MU-beta-gal cleaving activities were similar, 134.5 +/- 23.3 and 179.8 +/- 25.4 nmol/h/mg protein, respectively. In cultured skin fibroblasts and amniotic fluid cells these enzyme activities were 4 to 5 times higher. Homozygotes for GM1-gangliosidosis showed negligible activity while in heterozygotes the leukocyte GM1-cleaving activity was reduced to one-third of control values. In leukocytes from patients with four other sphingolipid storage diseases the activity was either normal (Krabbe's, Tay-Sachs, Metachromatic leukodystrophy) or increased (adult Gaucher's).
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PMID:GM1-ganglioside beta-galactosidase in leukocytes and cultured fibroblasts. 41 12

Metabolism of tritium-labelled galactosylceramide and lactosylceramide added to the culture medium was examined in cultured skin fibroblasts from 4 patients with globoid cell leukodystrophy (GLD) and 4 control individuals. The uptake of [3H]galactosylceramide and [3H]lactosylceramide by the fibroblasts continued actively at least up to 3 days. Approximately 30--40% of the galactosylceramide, which had been taken up, was released subsequently from the cells in a 4-day period, whereas only 10% of lactosylceramide was released during the same period. The GLD fibroblasts showed no abnormality in the kinetics of the uptake and in the release of these glycosphingolipids which are natural substrates of the beta-galactosidase genetically deficient in the disorder. This finding differs from that reported for fibroblasts from patients with metachromatic leukodystrophy, which showed abnormal accumulation and retention of sulfatide added to the culture media. However, degradation of added galactosylceramide to [3H]galactose by the GLD fibroblasts was only 25% of the control cells, while lactosylceramide was degraded at 70% of the normal rate. These findings are consistent with the known substrate specificities of the two acidic beta-galactosidases in human tissues; galactosylceramide is hydrolyzed almost exclusively by galactosylceramidase, while lactosylceramide can be hydrolyzed by both galactosylceramidase and GM1-ganglioside beta-galactosidase.
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PMID:Globoid cell leukodystrophy (Krabbe's disease). Metabolic studies with cultured fibroblasts. 73 Dec 65

Saposins are small, heat-stable glycoproteins required for the hydrolysis of sphingolipids by specific lysosomal hydrolases. Saposins A, B, C, and D are derived by proteolytic processing from a single precursor protein named prosaposin. Saposin B, previously known as SAP-1 and sulfatide activator, stimulates the hydrolysis of a wide variety of substrates including cerebroside sulfate, GM1 ganglioside, and globotriaosylceramide by arylsulfatase A, acid beta-galactosidase, and alpha-galactosidase, respectively. Human saposin B deficiency, transmitted as an autosomal recessive trait, results in tissue accumulation of cerebroside sulfate and a clinical picture resembling metachromatic leukodystrophy (activator-deficient metachromatic leukodystrophy). We have examined transformed lymphoblasts from the initially reported saposin B-deficient patient and found normal amounts of saposins A, C, and D. After preparing first-strand cDNA from lymphoblast total RNA, we used the polymerase chain reaction to amplify the prosaposin cDNA. The patient's mRNA differed from the normal sequence by only one C----T transition in the 23rd codon of saposin B, resulting in a threonine to isoleucine amino acid substitution. An affected male sibling has the same mutation as the proband and their heterozygous mother carries both the normal and mutant sequences, providing additional evidence that this base change is the disease-causing mutation. This base change results in the replacement of a polar amino acid (threonine) with a nonpolar amino acid (isoleucine) and, more importantly, eliminates the glycosylation signal in this activator protein. One explanation for the deficiency of saposin B in this disease is that the mutation may increase the degradation of saposin B by exposing a potential proteolytic cleavage site (arginine) two amino acids to the amino-terminal side of the glycosylation site when the carbohydrate side chain is absent.
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PMID:Characterization of a mutation in a family with saposin B deficiency: a glycosylation site defect. 232 May 74

Sphingolipid activator proteins (SAP) are relatively low-molecular-mass proteins that stimulate the hydrolysis of specific sphingolipids by the required lysosomal enzymes. SAP-1 or sulfatide/GM1 ganglioside activator protein has previously been demonstrated to stimulate the enzymatic hydrolysis of sulfatide, GM1 ganglioside and globotriaosylceramide. Using monospecific rabbit antibodies against human liver sulfatide/GM1 activator, the biosynthesis and processing of this activator were studied in cultured skin fibroblasts from controls and patients with GM1 gangliosidosis and a variant form of metachromatic leukodystrophy. When [35S]methionine was presented in the medium to control human fibroblasts for 4 h, the majority of the immunoprecipitable radiolabeling was confined to bands within three regions of apparent molecular mass 65-70, 35-52 and 8-13 kDa. The only immunoprecipitable radiolabeled species excreted into the medium when NH4Cl was present had an apparent molecular mass of 70 kDa. When the excretion products were given to fresh cells followed by incubation for up to 24 h there was production of the mature species. Treatment of the 70 kDa form with endoglycosidase F resulted in production of a 53 kDa molecular mass form. Pulse-chase experiments indicated that the initial immunoprecipitable translation product was 65 kDa which increased to 70 kDa over the next hour. The 65 kDa species must result from co-translational glycosylation of the polypeptide chain. Apparently, intralysosomal processing converts the 13 kDa form to the 8-11 kDa species. The cells from the patient with GM1 gangliosidosis could not process to the smallest species found in controls due to the deficiency of acid beta-galactosidase. Patients who have a variant form of metachromatic leukodystrophy do not make any immunoprecipitable radiolabeled products in the cells or in the media. This indicates a severe mutation in the gene coding for this activator protein. The production of such small mature species from a relatively large precursor form may regulate the production of this interesting protein.
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PMID:Biosynthesis of the sulfatide/GM1 activator protein (SAP-1) in control and mutant cultured skin fibroblasts. 308 Oct 38

Fibroblasts cultured from the skin of a patient with metachromatic leukodystrophy have been found to manifest the biochemical defect of this inborn error of metabolism, a deficiency of arylsulfatase A. Diseased cells had less than five per cent of normal arylsulfatase-A activity, while activities of other lysosomal enzymes-including arylsulfatase B, beta-galactosidase, beta-glucuronidase, and beta-N-acetylglucosaminidase-were comparable to those in control cells. The presence of dissociable inhibitors in extracts of the diseased cells was excluded by combination experiments. The deficiency of the enzyme in leukocytes was also confirmed and is comparable to that found in cultured fibroblasts. The finding that readily cultured fibroblasts from easily obtained skin biopsy specimens exhibit the enzymatic defect should prove valuable in the biochemical study of this disease.
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PMID:Metachromatic leukodystrophy: arylsulfatase-A deficiency in skin fibroblast cultures. 525 10

Sphingolipidoses are an heterogeneous group of inherited disorders of lipid metabolism affecting primarily the central nervous system. These disorders occur chiefly in the pediatric population, and the degenerative nature of the disease processes is generally characterized by diffuse and progressive involvement of neurones (gray matter) with psychomotor retardation and myoclonus or of fiber tracts (white matter) with weakness and spasticity. Biochemical research has identified the defects in the sphingolipidoses to specific lysosomal enzymes. For example, Niemann-Pick disease lacks sphingomyelinase; Krabbe's disease lacks galactocerebrosidase; Gaucher's disease lacks beta-D-glucosidase; metachromatic leukodystrophy lacks sulfatase; Tay-Sachs disease lacks hexosaminidase A; and generalized gangliosidosis lacks beta-galactosidase. Although there are no currently available modes of rendering corrective therapy in these disorders, a definitive diagnosis is possible both antepartum as well as postpartum. This information provides a sound and accurate basis for genetic counseling.
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PMID:Sphingolipidoses. 555 2

Cultured skin fibroblasts from the patient described by Shapiro and co-workers as having a variant form of metachromatic leukodystrophy (MLD) [Shapiro, L.J., Aleck, K. A., Kaback, M.M., Itabashi, H., Desnick, R.J., Brand, N., Stephens, R.L., Fluharty, A.L. & Kihara, H. (1979) Pediatr. Res. 13, 1179-1181] were confirmed to have a partial deficiency (25-40% of controls) of arylsulfatase A activity in vitro and a severe inability to metabolize [14C]stearic acid-labeled sulfatide presented in the medium. When 150 micrograms of purified activator protein for GM1 ganglioside beta-galactosidase and sulfatide sulfatase was added in 4 ml of medium with the 14C-labeled sulfatide, correction of the sulfatide metabolism to the normal range was found. Monospecific antibodies to this activator protein were prepared in rabbits, and they were used to examine cultured cells for the presence of crossreacting material by Ouchterlony double immunodiffusion and rocket immunoelectrophoresis. Cell extracts from controls and from patients with GM1 gangliosidosis and MLD were found to have a single line of identity. By comparison to known concentrations of purified activator protein, cell extracts from controls were found to have 0.76 +/- 0.32 micrograms of activator protein (mean +/- 1 SD, n = 10) per mg of solubilized protein, whereas those from patients with type 1 GM1 gangliosidosis and late infantile MLD had 1.53 and 1.41 micrograms/mg, respectively. Cell extracts from the patient with a variant form of MLD had no visible precipitin line by Ouchterlony double immunodiffusion and only a diffuse nonspecific region of staining by rocket immunoelectrophoresis. These immunologic studies provide evidence for a deficiency in the activator protein required for normal catabolism of sulfatide in the cells from this patient and possibly provide a method for diagnosis of similar patients.
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PMID:Immunological evidence for deficiency in an activator protein for sulfatide sulfatase in a variant form of metachromatic leukodystrophy. 613 82

Rectal mucosa biopsy specimens from patients with neuronal storage diseases were examined by electron microscopy. The diseases were Tay-Sachs disease, Sandhoff's disease, Niemann-Pick disease types B and C, late infantile metachromatic leukodystrophy, GM1 gangliosidosis type 1, beta-galactosidase-neuraminidase deficiency, I-cell disease, and mucopolysaccharidoses (Hunter's syndrome and Sanfilippo's syndrome type A). Unmyelinated nerve fibers, endothelial cells, fibroblasts, plasma cells, and histiocytes were seen in the specimens. Except for plasma cells, the results thus obtained for various cells were similar to those obtained from skin and conjunctival biopsy specimens, which have been already reported. There has been no report so far on ultrastructure of the plasma cell in these diseases. Storage materials, eg, dense bodies and membrane-bound vacuoles, were observed in the plasma cells in various storage diseases, with the exception of late infantile metachromatic leukodystrophy. Thus, electron microscopy of rectal mucosa is useful in making diagnoses and examining plasma cells in some neuronal storage diseases.
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PMID:Ultrastructural study of biopsy specimens of rectal mucosa. Its use in neuronal storage diseases. 689 82

Pairs of cultured amniotic cells and maternal fibroblasts ("feto-maternal pairs") were studied for hexosaminidase A (HXA) and arylsulfatase A (ASA) activity. These lysosomal enzyme activities are genetically deficient in Tay-Sachs disease and metachromatic leukodystrophy, respectively. After HXA was standardized by relating it to hexosaminidase B (HXB) activity, a feto-maternal correlation coefficient of r = 0.51 (n = 32; 95% confidence limits 0.197-0.73) was found for the HXA/HXB activity quotients. This coefficient was near the 0.5 value theoretically valid for mother-child pairs, suggesting that the studied activities reflect essentially the genetic variability. The studies of ASA revealed a high variability of individual activities, which was reduced in two steps: (1) The ASA activity was related to the mean of two lysosomal reference enzyme activities, total hexosaminidase and acid beta-galactosidase. (2) Since the square root of ASA activity was found to follow more closely the variation of the reference activities, the square root of ASA activity over the mean reference activity was taken as a more standardized measure of ASA activity, and the quotient was treated statistically. Positive feto-maternal correlation of standardized ASA activity was obtained after the elimination of three pairs with extreme values. A correlation coefficient of 4 = 0.42 (n - 26; 95% confidence limits 0.039-0.695) resulted. The implications of these correlation studies for the problem of heterozygote identification by quantitative enzyme assays in families deficient in HXA and ASA activity were considered.
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PMID:Genetic variation of hexosaminidase A and arylsulfatase A activity. Correlation study in amnio-maternal pairs of cultured cells. 728 80

Arylsulfatase A (ASA) and cerebroside-beta-galactosidase activities in leukocytes serve as a diagnostic tool for determining the presence of metachromatic leukodystrophy and globoid cell leukodystrophy, respectively. It has not been demonstrated whether a delay in blood processing and the presence of mixed cell types in different proportions in leukocytes affect the activities of the two enzymes in these cells. We have in the present study determined the specific activity in leukocytes and lymphocytes (T-cells) prepared from blood samples processed immediately after, 4, and 24 h after collection. In order to determine whether the enzyme activities in lymphocytes reflect expression of genetic trait, and not environmental or "state" influence, the activities of the two enzymes in interleukin 2-stimulated T-cells and resting T-cells were compared. A delay of up to 24 h in blood processing did not significantly change the specific activities of the two enzymes in both leukocytes and lymphocytes. The specific activity of ASA and beta-galactosidase in lymphocytes was 1.4-1.8 times that in leukocytes. The activities of the two enzymes in interleukin 2-stimulated T-cells did not differ from those in resting T-cells. These results indicate that blood-processing delay had no significant effects on ASA and beta-galactosidase activity. The data further indicate that the ASA and beta-galactosidase activity in interleukin 2-stimulated T-cells was not significantly different from resting lymphocytes from either normal or psychiatric subjects exposed to various medications. The activity levels in lymphocytes from psychiatric subjects thus reflect expression of genetic trait, rather than environmental or state influence.
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PMID:Arylsulfatase A and beta-galactosidase activities in leukocytes and lymphocytes from normal and psychiatric subjects. Effects of blood-processing delay and interleukin-2 stimulation. 775 46


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