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N Ui

Publications and source records attributed to N Ui.

At least 19 recordsLinked to original sources
PubMed1988

Colorimetry of dehydroalanine residues preserved as 'lost side chains' in thyroglobulin.

We developed a new assay method for dehydroalanine residues in thyroglobulin, which had been proposed to be the 'lost side chains' during thyroid hormonogenesis. Thyroglobulin preparations were labeled with 4-aminothiophenol at 30 degrees C for 10 days. Under the conditions, the reagent reacted only with dehydroalanine and cysteine residues. The 4-aminothiophenol bound to cysteine was eliminated by reductive cleavage. The 4-aminothiophenol-labeled dehydroalanine (4-aminophenylcysteine) residues were liberated by acidic hydrolysis, converted to a colored derivative by the Bratton-Marshall reaction and quantified colorimetrically. The number of dehydroalanine residues was the same as that of hormone residues in each thyroglobulin preparation. The results indicate that when one hormone residue is produced by the coupling of two iodotyrosine residues, the 'lost side chain' is preserved as one dehydroalanine residue in the thyroglobulin molecule.

Alanine↗
PubMed1986

Purification and characterization of human platelet proteoglycan.

Freshly prepared platelets were shown to contain glycosaminoglycans equivalent to 530 micrograms of hexuronate/10(11) platelets. When the platelets were extracted with 4 M-guanidinium chloride containing proteinase inhibitors, and the extract was dialysed extensively against 7 M-urea solution, almost all of proteoglycan was recovered in the urea-soluble fraction. The proteoglycan was purified from the urea-soluble fraction with a yield of 47% by DEAE-Sephacel chromatography, CsCl-density-gradient centrifugation, Bio-Gel A-15m gel filtration and then rechromatography on DEAE-Sephacel. The purified proteoglycan contained 30% glucuronic acid, 32% N-acetylgalactosamine, 14% sulphate and 15% protein. Serine, glutamic acid, glycine, aspartic acid and leucine accounted for 64% of the total amino acids. The Mr of the proteoglycan was assessed to be approx. 136000 by sedimentation-equilibrium methods. The galactosaminoglycan released by alkaline-borohydride treatment of the proteoglycan was converted stoichiometrically into 4-sulphated unsaturated disaccharide by digestion with chondroitinase AC-II, indicating that the galactosaminoglycan was fully sulphated chondroitin 4-sulphate. The apparent Mr of the chondroitin sulphate was assessed to be 28000 by gel filtration on Bio-Gel A-0.5m (KD 0.18). On two-dimensional electrophoresis on a cellulose acetate membrane, the chondroitin sulphate gave a single compact spot co-migrating with a reference chondroitin sulphate, indicating that the chondroitin sulphate chains were homogeneous in both length and charge density. On the basis of these results, the proteoglycan in human platelets was concluded to be a macromolecule of Mr 136000 containing four chondroitin 4-sulphate chains each with the apparent Mr of 28000.

Amino Acids↗
PubMed1985

Electron microscopy of monoclonal antibody-linked chains of thyroglobulin molecules.

Negative staining electron microscopy visualized immune complexes of hog thyroglobulin produced by 3 monoclonal antibodies, each towards a different conformation-dependent antigenic structure of the thyroglobulin. Equimolar mixtures of the thyroglobulin and any one of the 3 antibodies formed peculiar unbranched chains of 'ovoid' thyroglobulin molecules linked by the antibody molecules in an 'end to end' fashion. A mixture of the thyroglobulin and the 2 different antibodies produced branched chains. A set of 3 conformation-dependent antigenic structures was thus located near each end of the elongated thyroglobulin molecule. The results also indicated a topological similarity between the 2 subunits of thyroglobulin.

Animals↗
PubMed1985

Properties of thyroglobulins from normal thyroid and thyroid tumor on a concanavalin A-sepharose column.

Affinity chromatography on a concanavalin A (con A)-Sepharose column is a potentially useful for the isolation of whole thyroglobulin (Tg) at least from normal thyroid tissue. In addition to being a simple procedure for the isolation of Tg, large amounts of Tg can be applied to the column and recovered in good yield with a buffer containing MeG. In gradient elution with buffer containing increasing amounts of MeG, a single but broad peak was obtained, without separation into subfractions. However, a hemagglutination-inhibition test showed that the Tg preparation eluted early from the column had less affinity for con A than the Tg preparation eluted later, suggesting a heterogeneous distribution of carbohydrate moieties among Tg preparations. When human Tg from thyroid tumor was applied to the column, tumor Tg partly passed through the column without being adsorbed. This unadsorbed Tg showed a very low affinity for lectins, con A and wheat germ agglutinin (WGA), as determined by a double diffusion reaction in agar gel. In contrast to this fraction, the Tg adsorbed on the con A-gel column showed a very strong affinity for WGA, differing from Tg of normal thyroid tissue. Therefore, tumor Tg preparation appears to have an abnormally modified carbohydrate structure, at least in part. The higher affinity for WGA (with a specificity for N-acetylglucosamine) seen in adsorbed Tg could be due to a larger amount of GlcNAc residues which bind irregularly in the carbohydrate moiety of tumor Tg.

Adenoma↗
PubMed1981

Properties of peroxisomal 3-ketoacyl-coA thiolase from rat liver.

Peroxisomal 3-ketoacyl-CoA thiolase has a molecular weight of 89,000 and consists of 2 polypeptide chains of identical size. The enzyme has no interchain disulfide bonds and is reversibly dissociated to an inactive monomer in the cold. Mitochondrial 3-ketoacyl-CoA thiolase and acetoacetyl-CoA specific thiolase have molecular weights of 154,000 and 149,000, respectively. They each consist of 4 polypeptide chains of identical size. Peroxisomal thiolase and mitochondrial 3-ketoacyl-CoA thiolase operate by a ping-pong mechanism. The catalytic properties, including substrate specificity, of the peroxisomal enzyme were compared to those of mitochondrial 3-ketoacyl-CoA thiolase.

Acetyl-CoA C-Acetyltransferase↗
PubMed1977

Bioaffinity chromatography of thyrotropin using immobilized concanavalin A.

The behavior of crude preparations of whale and bovine thyrotropins was studied on an affinity column packed with concanavalin A-Sepharose. Only a small portion of the proteins applied was adsorbed to the column and eluted quantitatively with 0.5 M methyl-alpha-D-glucoside or -mannoside. Immunoreactive as well as hormonally active thyrotropin was recovered exclusively in the absorbed fraction. The usefulness of this chromatographic procedure for the group separation of pituitary glycoprotein hormones is discussed.

Animals↗
PubMed1977

Purification and properties of four biologically active components of whale luteinizing hormone.

Four biologically active components of luteinizing hormone (LH), designated as LH I, II, III, and IV, were isolated from whale pituitary glands. These components migrated as single bands with different mobilities in disc electrophoresis, and their isoeletric points were at pH 8.1, 8.3, 8.5, and 8.7, respectively. Their amino acid and carbohydrate compositions showed close similarity. The molecular weight of whale LH was determined to be 31,000 by sedimentation equilibrium, and no difference was detected among the four components. The molecular properties of whale LH were compared with the previously reported data for LH from other animal species.

Amino Acids↗
PubMed1976

The presence of N-terminal pyroglutamyl residues in hog thyroglobulin.

A method was devised to isolate N-terminal peptide fragments from the polypeptide chains constituting thyroglobulin even in the case when the terminal amino groups are naturally blocked, for instance, acylated. Reduced and carboxymethylated hog thyroglobulin was first acetylated and digested with thermolysin. The blocked N-terminal peptide fragments were separated from the unblocked N-terminal fragments by column chromatography on Dowex 50, then on Dowex 1 after dinitrophenylation, and finally fractionated into ten fractions by paper chromatography after gel filtration on Sephadex G-10. Structural analyses by enzymic or partial acid hydrolysis of these peptide fractions failed to detect N-terminal acetyl amino acid. Instead, pyroglutamyl peptides including pyroglutamylleucine were found. By the same method, acetylated lysine and glycine were identified for chicken lysozyme and horse myoglobin, respectively. The use of thermolysin because of its unique specificity, and the possible relevance of the present result to the previous data on the N-terminal analysis of thyroglobulin are discussed.

Amino Acid Sequence↗
PubMed1976

Purification and properties of whale thyroid-stimulating hormone III. Properties of isolated multiple components.

Properties of the four purified components of whale thyroid-stimulating hormone (TSH) have been compared. The amino acid composition shows close similarity among these components. Their hexosamine and sialic acid contents are of the same magnitude, whereas the neutral sugar composition differs somewhat from each other. The molecular weight of whale TSH determined by sedimentation equilibrium is 29,000, and no difference in molecular weight as well as in Stokes radius as determined by gel filtration has been detected among these four components. The amino acid and carbohydrate compositions of whale TSH resemble those of TSH from other species, especially those of non-primate mammalian TSH. Whale TSH contains, unlike bovine TSH but like human TSH, 1-2 residues of sialic acid as a constituent carbohydrate.

Amino Acids↗