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Biomedical subjects

A Reglero

Publications and source records attributed to A Reglero.

70 records · Page 4Linked to original sources
PubMed1982

[Glycosidases of mammals: association of activities and changes of levels in some disorders].

beta-Galactosidase and associated activities (beta-glucosidase and beta-fucosidase) have been studied in rabbit and bovine liver and rabbit spleen. The physico-chemical (optimal pH, pI, MW) and kinetical (Km, Vmax, Ki) properties were determined for all the activities. Two enzyme forms were separated in rabbit spleen. beta-Galactosidase, beta-fucosidase and beta-glucosidase activities were catalyzed by the same enzyme in rabbit and bovine liver. The enzyme from bovine liver showed nonlinear double-reciprocal plots, suggesting a substrate-activation model, and the presence of more than one binding site in the enzyme. The enzyme activities of several glycosidases were determined in human sera fom control groups and from patients with diabetes mellitus, pancreatitis, hepatitis, cirrhosis, stomach and breast cancer, myocardial infarction and renal failure. The results show significantly different enzyme levels for several glycosidases in all the studied diseases. Experimentally-induced diabetes mellitus, alcoholism and nephrotoxicity in rats showed different glycosidase levels in several tissues, as compared with control groups.

Alcoholism↗
PubMed1982

[Gangliosides of neural and extraneural tissues of various species of mammals].

The ganglioside patterns of the forebrain, cerebellum and brain stem from horse, donkey, mule and goat have been determined by thin-layer chromatography. GM1, GD1a, GD1b and GT1b are the four major brain gangliosides. N-acetylneuraminic acid as the predominant sialic acid (congruent to 97%) and traces of N-glycolyneuraminic acid were found. The four above mentioned major gangliosides were also found in the forebrain, cerebellum and brain stem of adult rats. This pattern is not modified in rats under stress situation (at 4 degrees C for 3 months). In other extraneural organs from rats such as liver and kidney the patterns differ from those of the neural organs. Pig spleen lymphocyte gangliosides were studied by thin-layer chromatography. Their patterns show remarkable differences in comparison to those of neural organs. These gangliosides were also separated by DEAE Sephadex chromatography into two peaks, I and II. Peak I contains mainly monosialogangliosides and peak II contains disialogangliosides. No trisialogangliosides were practically detected in the material. Sheep platelets contain GM3 as predominant ganglioside.

Animals↗
PubMed1982

[Neuraminidase of influenza virus].

Neuraminidase or sialidase (EC 3.2.1.18, acylneuraminyl hydrolase) from a strain of the influenza virus A (H3N2), identical to the A/Hong Kong/68 (H3N2) strain, has been purified and characterized by electrofocusing; only about 20% of the previous enzymic activity was lost after electrofocusing. The enzyme activity was measured by the peryodate-thiobarbiturate procedure, by the methoxyphenol-antipyrine method, and by spectrophotometry at 340 nm of the NADH produced in the oxidation of the beta-galactose + NAD+; this beta-galactose was released from lactose by beta-galactosidase; and lactose was liberated from N-acetylneuraminyl-lactose by the neuraminidase activity. The results of the interference by some chemical compounds, which are not true inhibitory agents for the enzyme, on the peryodate-thiobarbiturate reaction are indicated, as well as the detection of other compounds which are true inhibitors of this enzyme in vitro. This neuraminidase was able to release sialic acid with linkages alpha 2-3, alpha 2-6 and alpha 2-8 from several substrates, but with very different efficiency. Natural substrates such as the oligosaccharide N-acetylneuraminyl-lactose, glycoproteins (fetuin, bovine horse brain, colominic acid, and synthetic substrates such as 5-N-acetyl-2-O-(3-methoxyphenyl)-alpha-D-neuraminic acid and 2'-(4-methyl umbellyferil)-alpha-D-N-acetylneuraminic acid were hydrolyzed by this enzyme. Finally, the finding of neuraminidase in ovine, equine and porcine platelet is summarized.

Animals↗
PubMed1980

Neuraminidase from influenza virus A (H3N2): specificity towards several substrates and procedure of activity determination.

Neuraminidase (acylneuraminyl hydrolase, EC 3.2.1.18) from the influenza virus A/Hong Kong/68 (H3N2) was purified after treatment of the purified virus with sarcosyl (sodium laurylsarcosinate), centrifugation at 110 000 x g, and chromatography on DEAE-Sephadex and Sephadex G-200. It migrated as a single component during electrophoresis on polyacrylamide gel, and its molecular weight was estimated about 270 000. The enzyme was thermolabile, the activity being reduced to 60% in 10 min at 50 degrees C. The purified neuraminidase had an apparent Km value of 4.1 . 10(-3) M for 5-N-acetyl-2-O-(3-methoxyphenyl)-alpha-D-neuraminic acid and was able to release sialic acid with linkages alpha 2-3, alpha 2-6 and alpha 2-8 (with very different efficiency) from fetuin, gangliosides, colominic acid, and bovine and porcine submaxillary mucins. The enzymic activity was measured by several procedures: (A) spectrophotometric determination at 340 nm of the NADH produced in the reaction catalysed by beta-galactose dehydrogenase on beta-galactose + NAD+, this beta-galactose was the product released from lactose by beta-galactosidase and lactose was the product of the neuraminidase activity on N-acetylneuraminyl-lactose; (B) determination of the colored quinone yielded by the liberated methoxyphenol with 4-aminoantipyrine (Santer, U.V., Yee-Foon, J. and Glick, M.C. (1978) Biochim. Biophys. Acta 523, 435-442); (C) periodate-thiobarbiturate procedures (Warren, L. (1959) J. Biol. Chem 234, 1971-1975 or Aminoff, D. (1961) Biochem. J. 81, 384-391). Some peculiarities of these methods are discussed.

Gangliosides↗
PubMed1980

Increased serum alpha-L-fucosidase and beta-N-acetylglucosaminidase activities in diabetic, cirrhotic and gastric cancer patients.

The activities of several glycosidases (alpha-L-fucosidase, alpha-D-mannosidase, alpha-D-galactosidase, beta-D-galactosidase, beta-N-acetylglucosaminidase and beta-D-glucuronidase) were determined in human sera from 10 normal subjects and in three groups each of 10 patients with diabetes mellitus, hepatic cirrhosis and gastric carcinoma. The results show significantly higher activities in the patients for alpha-L-fucosidase (p less than 0.001) and for beta-N-acetylglucosaminidase (p less than 0.1, p less than 0.001 and p less than 0.05, respectively), and smaller or not significantly greater values for the other glycosidases.

Acetylglucosaminidase↗
PubMed1978

Purification and properties of beta-N-acetylhexosaminidase from the mollusc Helicella ericetorum Müller.

1. A beta-N-acetylhexosaminidase was purified 330-fold from the digestive gland of the terrestrial mollusc Helicella ericetorum Müller. 2. Its pH optimum is 4.5 for both beta-N-acetylglucosaminidase and beta-N-acetylgalactosaminidase activities in two buffer solutions; it is fully stable at 37 degrees C for 2h in the pH range 3.8--4.6 and shows one isoelectric point (pH 4.83). 3. The estimated mol.wt. is between 120,000 and 145,000. 4. The enzyme shows an endo-beta-N-acetylhexosaminidase activity on natural substrates such as ovalbumin, ovomucoid, chondroitin 4-sulphate, chitin and hyaluronic acid. 5. Two forms of the enzyme were separated by preparative polyacrylamide-gel electrophoresis. 6. Km and Vmax. for p-nitrophenyl 2-acetamido-2-deoxy-beta-D-glucopyranoside and p-nitrophenyl 2-acetamide-2-deoxy-beta-D-galactopyranoside are 0.43 mM, 30.1 micronmol of p-nitrophenol/min per mg and 0.19 mM, 8.6 micronmol of p-nitrophenol/min per mg respectively. 7. It is inhibited by Hg2+, Fe3+, acetate, some lactones, N-acetylgalactosamine, N-acetylglucosamine and mannose. 8. Mixed-substrates analysis and Ki values for competitive inhibitors indicated that beta-N-acetylglucosaminidase and beta-N-acetylgalactosaminidase activities are catalysed by the enzyme at the same active site.

Animals↗
PubMed1977

Acetyl glutamate--a model of signals for intracellular proteolysis.

The proteolysis at neutral pH of mitochondria from liver and brain is more marked in isolated preparations than "in vivo" indicating activation of proteases or inactivation of repressors during isolation. Acetyl glutamate (AG), found in liver mitochondria of ureotelic animals, plays a crucial role as activator of carbamylphosphate synthetase. Since AG levels change under a number of conditions, we checked for an AG deacylase in mitochondria, for otherwise AG must be exported and destroyed by cytosol deacylases. We noted on incubation of mitochondrial extracts with AG an increase in trichloracetic acid-soluble ninhydrin-reacting material but not in acetate liberation, indicating activation of proteases. This was checked with 14C-labelled mitochondria. Under certain conditions AG and other acyl aminoacids stimulate approximately 5 to 20% the proteolysis with rat live and with brain mitochondria.

Animals↗
PubMed1976

Glycosidases of molluscs. Purification and properties of alpha-L-fucosidase from Chamelea gallina L.

An alpha-L-fucosidase had been purified approximately 300-fold from the liver (hepatopancreas) of the marine mollusc Chamelea gallina L. (= Venus gallina L.). During the different steps of the purification procedure it was difficult to remove the contaminant N-acetylglucosaminidase activity; but, after electrofocusing, a final preparation free of this and other glycosidades present in the crude extract was obtained. The purified enzyme has a broad specificity; it hydrolyzes p-nitrophenyl alpha-L-fucoside and natural substrates such as oligosaccharides containing fucosidic residues with alpha 1--2, alpha 1--3 and alpha 1--4 linkages; also it hydrolyzes fucose-containing glycopeptides, such as thyroglobulin glycopeptide, and glycoproteins as procine submaxillary mucin (previously rendered free of sialic acid). The enzyme has a pH optimum of 5.2 +/- 0.2, with a Km of 7 X 10(-5) M using p-nitrophenyl L-fucoside as substrate. It is inhibited by Hg2+ and some sugars, and activated by CN-, Zn2+, Ca2+ and EDTA. It shows two peaks by isoelectric focusing (at 6.3 and 6.6). The molecular weight of the alpha-L-fucosidase by gel filtration was over 2000000.

Animals↗
PubMedDate not supplied

O-acetylated sialic acids in gangliosides from pig spleen lymphocytes.

The sialic acid content of gangliosides from pig spleen lymphocytes was studied by thin-layer chromatography. N-glycolylneuraminic acid and N-acetylneuraminic acid were detected for the first time in this material as the major sialic acids. In addition, two other sialic acids, tentatively designated O-acetylated sialic acids, according to their RF values on cellulose plates, were also found. We have detected several gangliosides showing a retarded migration pattern in two dimensional thin-layer chromatography with an intermediate ammonia treatment. One of these gangliosides could be an O-acetylated derivative of the disialoganglioside GD3, since after de-O-acetyation it co-migrates with GD3. Another ganglioside co-migrated with GM2 before the alkaline treatment; however, after the treatment it was also retarded and co-migrates with GD3.

Acetylation↗