A low-molecular-weight protein cross-reacting with human liver N-acetyl-beta-D-glucosaminidase.
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ABSTRACT:
SUBMITTER: Carroll M
PROVIDER: S-EPMC1166107 | biostudies-other | 1974 Feb
REPOSITORIES: biostudies-other
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Project description:Albuminuria is a well known risk factor for cardiovascular disease and mortality, but focus on renal tubular dysfunction as a potential risk factor is growing also. The association between the urinary activity of N-acetyl-β-D-glucosaminidase (NAG) and cardiovascular risk has been assessed mostly in cross-sectional studies. We studied the cross-sectional associations between urinary NAG and cardiovascular risk factors and the longitudinal associations between NAG, cardiovascular disease, and all-cause mortality in a general population. Urinary NAG/creatinine ratio (NAG ratio) and albumin/creatinine ratio (ACR) were measured in 6834 participants of the Tromsø Study in 1994-1995. During the median 17.5 years of follow-up, 958 myocardial infarctions, 726 ischemic strokes, and 2358 deaths were registered. In multivariable analyses adjusted for albuminuria and cardiovascular risk factors, a baseline NAG ratio in the highest quartile was associated with an increased risk of myocardial infarction (hazard ratio [HR], 1.43; 95% confidence interval [95% CI], 1.16 to 1.76), ischemic stroke (HR, 1.41; 95% CI, 1.10 to 1.80), and all-cause mortality (HR, 1.60; 95% CI, 1.39 to 1.84). Combined, ACR and NAG ratio above median associated with a 48%-80% increased risk for the three end points. However, the NAG ratio did not add significantly to the baseline risk-prediction models when assessed by area under the receiver operating characteristics curve or net reclassification improvement. In conclusion, the nonsignificant improvement of risk prediction does not support the clinical use of NAG ratio in cardiovascular risk assessment in a low-risk group.
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Project description:Antisera were raised to a partially purified preparation of human liver hexosaminidase and to highly purified preparations of hexosaminidase isoenzymes A and B. All the antisera precipitated the enzyme in an enzymically active form, which could be located on immunodiffusion and immunoelectrophoretic gels by using a histochemical substrate. The antisera to the purified isoenzymes were shown to react with hexosaminidase from human liver, kidney, brain and spleen, but did not cross-react with human liver beta-glucosidase, beta-galactosidase, alpha-mannosidase, beta-xylosidase, arylsulphatase or acid phosphatase. Hexosaminidases A and B were immunologically identical. The immunological properties of the hexosaminidases from livers of patients with three types of GM(2)-gangliosidoses were closely similar. No evidence could be found for cross-reacting material in enzyme-deficient states.
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Project description:This study aimed to test the influence of functional renal organic cation transporters (OCT2 in humans, Oct1 and Oct2 in mice) on biomarkers of cisplatin nephrotoxicity, such as urinary activity of N-acetyl-beta-D-glucosaminidase (NAG).Temporal cisplatin-induced nephrotoxicity was assessed by histopathology and biomarkers. Cisplatin-mediated NAG changes and survival were determined in wild-type and Oct1/2(-/-) mice. Identification of OCT2 inhibitors was done in transfected 293Flp-In cells, and the NCI(60) cell line panel was used to assess contribution of OCT2 to cisplatin uptake in cancer cells.Classical biomarkers such as blood urea nitrogen and serum creatinine were not elevated until 72 hours after cisplatin administration and substantial kidney damage had occurred. Oct1/2(-/-) mice had 2.9-fold lower NAG by 4 hours (P < 0.0001) and 2.3-fold increased survival (P = 0.0097). Among 16 agents, cimetidine strongly inhibited uptake of tetraethylammonium bromide (P = 0.0006) and cisplatin (P < 0.0001), but did not have an influence on cisplatin uptake in SK-OV-3 cells, the cancer line with the highest OCT2 mRNA levels. In wild-type mice, cimetidine inhibited cisplatin-induced NAG changes (P = 0.016 versus cisplatin alone) to a degree similar to that seen in Oct1/2(-/-) mice receiving cisplatin (P = 0.91). Cumulative NAG activity of >0.4 absorbance units (AU) was associated with 21-fold increased odds for severe nephrotoxicity (P = 0.0017), which was linked with overall survival (hazard ratio, 8.1; 95% confidence interval, 2.1-31; P = 0.0078).Cimetidine is able to inhibit OCT2-mediated uptake of cisplatin in the kidney, and subsequently ameliorate nephrotoxicity likely with minimal effect on uptake in tumor cells.
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Project description:Endo-N-acetyl-beta-D-glucosaminidase activity towards an oligomannosidic type glycoamino acid substrate was found in the soluble fraction of rat liver and kidney. No evidence for a lysosomal form of the activity was found.
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Project description:N-Acetyl-beta-D-glucosaminidase activities were determined in homogenates of marmoset kidney, in serum and in urine by using the 4-methylumbelliferyl substrate. The enzyme activity was separated into several components by DEAE-cellulose ion-exchange chromatography, starch-gel electrophoresis and isoelectric focusing. The kidney contained two major forms of the enzyme, A and B, which had similar pH optima and Km values. The A-form bound to DEAE-cellulose at pH 6.8, migrated towards the anode on starch-gel electrophoresis and had a pI of 5.0. The B-form did not bind to DEAE-cellulose at pH 6.8, remained near the origin on starch-gel electrophoresis and had a pI of 7.64. The isoenzymes also differed in heat stability, the B-form being the more stable. Serum contained B-form activity and, in addition, two intermediate forms (I1 and I2) were loosely bound to DEAE-cellulose. The serum A-form activity was less firmly bound to DEAE-cellulose than was the tissue A-form and was designated As. Serum from a pregnant marmoset contained a form which may be analogous to the human P-isoenzyme. Urine contained only a small amount of B-form activity, the majority being present in the A-form. The kidney A- and B-forms both had mol.wts. of 96000--100000 and the activity was predominantly lysosomal. Partial purification of the kidney A isoenzyme was undertaken. Immunoprecipitation studies indicated a relationship between marmoset kidney A-form and human liver A-form activity.
| S-EPMC1186147 | biostudies-other
Project description:Those proteins of human liver that cross-reacted with antibodies raised to apparently homogenous hexosamindases A and B were detected by immunodiffusion. Cross-reacting proteins with high molecular weights (greater than 2000000) and intermediate molecular weights (70000--200000) were present both in the unadsorbed fraction and in the 0.05--0.2M-NaCl eluate obtained by DEAE-cellulose chromatography at pH7.0. The unadsorbed fraction also contained a cross-reacting protein of low molecular weight (10000--70000). The possible structural and functional relationships between hexosaminidase and the cross-reacting proteins are discussed. An apparently cross-reacting protein present in the 0.05M-NaCl eluate from the DEAE-cellulose column was serologically unrelated to hexosaminidase, but it gave a reaction of immunological identify with one of the apparently cross-reacting proteins having the charge and size characteristics of hexosaminidase A. It is suggested that immunochemical methods may provide criteria for the homogeneity of enzyme preparations superior to those of conventional methods.
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Project description:Neuronal cell bodies, isolated in bulk from 8-day-old rat cerebral cortices, were incubated in the presence of a 3H-labelled amino acid mixture, and subcellular fractions isolated by differential centrifugation. The particulate fractions were frozen/thawed in 0.20 M-sucrose/0.1 M-KCl [Selling et al. (1973) Biochim. Biophys. Acta 315, 128-146] and the profiles of acid-insoluble radioactivity and N-acetyl-beta-D-glucosaminidase (glucosaminidase) activity compared in the resulting non-sedimentable fractions by DEAE-cellulose chromatography and cellulose acetate electrophoresis. Radioactivity and glucosaminidase activity co-migrated to a significant extent. Electrophoresis revealed that after 1 min of incubation 42% of the radioactivity of the non-sedimentable microsomal fraction after freezing and thawing co-migrated with an intensely fluorescent band of glucosaminidase activity. Since the pellet fraction obtained on freezing/thawing the microsomal fraction contained up to 75% of the RNA, 95% of the radioactivity and 45% of the glucosaminidase, a detailed study of the association between its radioactivity and nascent glucosaminidase activity was undertaken. After 1 and 2 min of incubation, followed by centrifugation of the microsomal pellet on 35-60% (w/v) sucrose density gradients, radioactivity and glucosaminidase activity exhibited parallel profiles in the region of heavy polyribosomes and at the top of the gradient which contains spontaneously released nascent polypeptide chains. DEAE-cellulose chromatography of these chains revealed glucosaminidase A to be the principal nascent glucosaminidase component, with glucosaminidases B and C as minor peaks. After 2 min of incubation, all of the glucosaminidase components appeared labelled, and glucosaminidase A exhibited two distinct sub-components. The pattern of glucosaminidase labelling in the soluble and microsomal fractions suggested that newly formed glucosaminidase molecules traverse both the cellular sap and the lumen of the endoplasmic reticulum. Only glucosaminidase A reacted specifically with concanavalin A and radioactive glucosaminidase A could be successfully regenerated by treatment with alpha-methyl-D-glucoside. Glucosaminidase A and a substantial portion of the radioactivity associating with it could be readily converted into glucosaminidase B by re-chromatography on DEAE-cellulose and by reaction of the concanavalin A-glucosaminidase A complex with methyl glucosides.
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Project description:The archaeal exo-β-d-glucosaminidase (GlmA), a thermostable enzyme belonging to the glycosidase hydrolase (GH) 35 family, hydrolyzes chitosan oligosaccharides into monomer glucosamines. GlmA is a novel enzyme in terms of its primary structure, as it is homologous to both GH35 and GH42 β-galactosidases. The catalytic mechanism of GlmA is not known. Here, we summarize the recent reports on the crystallographic analysis of GlmA. GlmA is a homodimer, with each subunit comprising three distinct domains: a catalytic TIM-barrel domain, an α/β domain, and a β1 domain. Surprisingly, the structure of GlmA presents features common to GH35 and GH42 β-galactosidases, with the domain organization resembling that of GH42 β-galactosidases and the active-site architecture resembling that of GH35 β-galactosidases. Additionally, the GlmA structure also provides critical information about its catalytic mechanism, in particular, on how the enzyme can recognize glucosamine. Finally, we postulate an evolutionary pathway based on the structure of an ancestor GlmA to extant GH35 and GH42 β-galactosidases.
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Project description:An endo-N-acetyl-beta-D-glucosaminidase activity towards an asialo-N-acetyl-lactosaminic-type glycoasparagine substrate was demonstrated in rat liver. This activity was optimal at pH 7.0 and was predominantly present in the soluble (cytosolic) fraction.
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Project description:1. The activities of beta-galactosidase, beta-glucosidase, beta-glucuronidase and N-acetyl-beta-glucosaminidase from rat kidney have been compared when 4-methylumbelliferyl glycosides are used as substrates. 2. Separation by gel electrophoresis at pH7.0 indicated slow- and fast-moving components of rat-kidney beta-galactosidase. 3. The fast-moving component is also associated with the total beta-glucosidase activity and inhibition experiments indicate that a single enzyme species is responsible for both activities. 4. DEAE-cellulose chromatography and filtration on Sephadex gels suggests that the beta-glucosidase component is a small acidic molecule, of molecular weight approx. 40000-50000, with optimum pH5.5-6.0 for beta-galactosidase and beta-glucosidase activities. 5. The major beta-galactosidase component has low electrophoretic mobility, a calculated molecular weight of 80000 and optimum pH3.7.
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