Structural determination of D-fructans from Streptococcus mutans, serotype b, c, e, and f strains, by 13C-n.m.r. spectroscopy.
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Fructans↗
Biomedical subjects
A Shimamura
Publications and source records attributed to A Shimamura.
Merkel-neurite complexes in the fungiform papillae of two species of monkeys.
Merkel-neurite complexes in tongues of Japanese and cynomolgus monkeys were examined by means of light and electron microscopy. Merkel-neurite complexes were found preferentially in the epithelium of fungiform papillae located at the tip of the tongue. It appears that the anterior fungiform papillae of the monkey are highly adapted for both taste and mechanical sensation.
Animals↗
Monoamine-containing basal cells in the taste buds of the newt Triturus pyrrhogaster.
Monoamine-containing cells were examined by fluorescence histochemistry and electron microscopy. Two or three serotonin-like fluorescent cells were located just above the basal lamina and failed to reach the free surface of the taste bud. Ultrastructurally this cell type was characterized by the presence of dense-cored vesicles and finger-like cytoplasmic processes. Many characteristics of Merkel cells were present.
Amines↗
Purification and characterization of extracellular glucosyltransferase from Streptococcus mutans serotype b (subspecies rattus).
An extracellular glucosyltransferase (GT-S) synthesizing water-soluble glucan was purified from the culture supernatant of Streptococcus mutans BHT (serotype b, subsp. rattus) by DEAE-Sepharose chromatography and preparative isoelectric focusing. The Mr of the enzyme was 155,000 and the pI was 4.5. The GT-S had a specific activity of 10.2 i.u. (mg protein)-1, an optimum pH of 6.0 and a Km value of 0.8 mM for sucrose, and was activated twofold by dextran T10. The GT-S was immunologically partially identical with the corresponding enzymes in crude preparations from serotypes c, e and f. The glucan synthesized de novo from sucrose by the GT-S was water-soluble and consisted of 29 mol% of non-reducing terminal, 49 mol% of 1,6-alpha-linked, 11 mol% of 1,3-alpha-linked and 11 mol% of 1,3,6-alpha-branched glucose residues.
Animals↗
The ultrastructure of encapsulated sensory corpuscles in the fungiform papillae of monkeys.
Both simple and coiled simple encapsulated sensory corpuscles in the fungiform papillae of primate tongues were examined by light and electron microscopy. These were found to be composed of discoid axon terminals, with cytoplasmic lamellae of lamellar cells surrounding them. The axon terminals were characterized by the presence of distinct finger-like projections extending beyond the corpuscular basal lamina to make contact with collagen fibers, as well as numerous mitochondria, clear vesicles and a few dense-core vesicles in the axoplasm. The cytoplasmic lamellae of lamellar cells showed a number of caveolae on the plasma membrane. Further, desmosome-like contacts were found between adjacent lamellae and between the axon and the innermost lamella.
Animals↗
Fine structure of taste buds in the tongue, palatal mucosa and gill arch of the axolotl, Ambystoma mexicanum.
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Ambystoma↗
Purification and properties of extracellular glucosyltransferase synthesizing 1,6-, 1,3-alpha-D-glucan from Streptococcus mutans serotype a.
An extracellular glucosyltransferase (sucrose: 1,6-, 1,3-alpha-D-glucan 3-alpha- and 6-alpha-D-glucosyltransferase, EC 2.4.1.-) of Streptococcus mutans HS6 (serotype a) was purified from culture supernatant by DEAE-Sepharose chromatography and preparative isoelectric focusing. The molecular weight measured by SDS-PAGE was 159 000 and the isoelectric point was pH 4.9. The specific activity was 89.7 i.u. (mg protein)-1 and the optimum pH was 6.0. The Km value for sucrose was 4.9 mM and the enzyme activity was not stimulated by exogenous dextran T10. Glucan was synthesized de novo from sucrose by the purified enzyme and consisted of 49.1 mol% 1,6-alpha-linked glucose and 33.9 mol% 1,3-alpha-linked glucose, with 13.6 mol% terminal glucose and 3.3 mol% 1,3,6-alpha-branched glucose.
Extracellular Space↗
Purification and properties of extracellular glucosyltransferase synthesizing 1,3-alpha-D-glucan from Streptococcus mutans serotype a.
Extracellular 1,3-alpha-D-glucan synthase (sucrose: 1,3-alpha-D-glucan 3-alpha-D-glucosyltransferase, EC 2.4.1.-) of Streptococcus mutans HS6 (serotype a) was purified from culture supernatant by ultrafiltration, DEAE-Sepharose chromatography and preparative isoelectric focusing. The enzyme had a molecular weight of 158 000 by SDS-PAGE and an isoelectric point of pH 5.2. The specific activity of the enzyme was 48.3 i.u. (mg protein)-1. The Km for sucrose was 1.2 mM and the activity was optimal at pH 6.0. The enzyme activity was stimulated about 20-fold in the presence of dextran T10. Glucan was synthesized de novo from sucrose by the enzyme and characterized as a linear 1,3-alpha-D-glucan by GC-MS.
Chromatography, Ion Exchange↗
Isolation and characterization of an extracellular glucosyltransferase synthesizing insoluble glucan from Streptococcus mutans serotype c.
A glucosyltransferase which synthesized insoluble glucan in polyacrylamide gel was isolated from the culture supernatant of Streptococcus mutans Ingbritt (serotype c) by ultrafiltration, ethanol fractionation, isoelectric focusing, and preparative gel electrophoresis. The enzyme preparation was electrophoretically homogeneous and immunologically distinct from the highly branched 1,6-alpha-D-glucan synthase and fructosyltransferase from the same strain and glucosyltransferases from serotypes a and g. The molecular weight was 99,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the isoelectric point was 8.5. The enzyme had the optimum pH of 6.0 and Km value for sucrose of 9.4 mM. Besides the insoluble glucan with 96% 1,3-alpha linkage, this enzyme synthesized a considerable amount of diffusible glucan with 84% 1,6-alpha linkage, separately. This enzyme may be the one released from the enzyme aggregates by extracellular proteases, because the addition of extraneous trypsin to the crude enzyme preparation increased the amount of the enzyme species.
Animals↗
Fine structure of monoamine-containing basal cells in the taste buds on the barbels of three species of teleosts.
The taste buds on the barbels in three species of teleosts (Cyprinus carpio, Misgurnus anguillicaudatus, Parasilurus asotus) were studied by means of fluorescence- and electron microscopy. Intensely yellow-fluorescent cells, which are disk-shaped and located exclusively in a basal position, are observed in the barbel-buds of all fishes examined. The basal cells contain a large number of small clear vesicles approximately 40-60 nm in diameter, which show a tendency to aggregate in the cytoplasm facing the junction of the nerve terminals; chemically transmitting synapses are seen in the latter region. It is suggested from the present observations that the basal cells in the barbel-bud may originate from Schwann cells and have a dual function both as mechanoreceptors and paracrine elements. Since the administration of 5,6-DHT results in an appearance of small dense vesicles among the small clear vesicles, the possibility exists that the basal cell may be capable of taking up monoamines and storing them in the small clear vesicles.
5,6-Dihydroxytryptamine↗
Ultrastructural and histochemical changes in the frog taste organ following denervation.
The fine structure of the taste organ in the Rana catesbeiana was observed by light and electron microscopy. The taste organ consists of three distinct cell types, the taste, supporting and basal cells as well as nerve elements. The present findings suggest that the taste cell might function not only as a chemoreceptor cell, but also as a paracrine cell. The basal cell also may have a dual function as both mechanoreceptor and paracrine cell. Furthermore, taste organs have been examined at intervals from 3 hrs to 120 days after sectioning of the glossopharyngeal nerves. The taste organs were almost intact throughout the experimental period after denervation and even after ceasing to produce impulses from chemical or mechanical stimuli. The dense-cored vesicles of the taste or basal cells, which may possess a paracrine action, still remain in the taste organ even 120 days after denervation. It can be concluded that the morphological integrity of the frog taste organ does not absolutely need the presence of the gustatory fibers in contrast to the nerve-dependent nature of the mammalian taste bud.
Adenosine Triphosphatases↗
Three kinds of extracellular glucosyltransferases from Streptococcus mutans 6715 (serotype g).
In addition to the 1,3-alpha-D-glucan synthetase (pI 4.9) and the highly-branched 1,6-alpha-D-glucan synthetase (pI 3.9-4.1), Streptococcus mutans 6715 (serotype g) was found to secrete the third glucosyltransferase in multiple forms (pI 5.5-7.0), which exhibited 87% 1,6-alpha-bond-, 6% 1,3-alpha-bond- and 7% 1,3,6-branch-forming activities. The production of this enzyme was extremely enhanced when the organism was grown in Tween 80-supplemented medium. The 3 glucosyltransferases from the same organism were enzymatically and immunologically distinct from each other, and they were commonly found among the serotype g strains.
Chemical Phenomena↗
Purification and properties of extracellular glucosyltransferases from Streptococcus mutans serotype a.
Extracellular glucosyltransferases (sucrose: 1,6-alpha-D-glucan 3-alpha- and 6-alpha-glucosyltransferase) of Streptococcus mutans HS6 (serotype a) were purified from the culture supernatant by DEAE-Sepharose chromatography, ConA-Sepharose chromatography and chromatofocusing. The enzymes I and II with specific activities of 6.20 and 5.86 i.u. mg-1, respectively, exhibited slightly different isoelectric points (pI 4.5 and 4.2) and the molecular weights were estimated to be 161000 and 174000, respectively, by SDS-PAGE. The enzymes had the same optimum pH of 5.5 and the same Km values of 1.3 mM for sucrose and of 83 microM-glucose equivalent for dextran T10. By double immunodiffusion test on agar, these enzymes were immunologically identical to each other. Analysis by GLC of the glucans synthesized de novo from sucrose by the enzymes (I and II) established that they were 1,6-alpha-D-glucans with 20 and 24.5 mol% 1,3,6-branch points, respectively. Both are therefore bifunctional enzymes.
Carbohydrate Conformation↗
Comparative study of Streptococcus mutans extracellular glycosyltransferases by isoelectric focusing.
Extracellular glycosyltransferases from 17 strains of Streptococcus mutans were examined by analytical isoelectric focusing. Three kinds of glucosyltransferase: highly-branched-1,6-alpha-D-glucan synthetase, 1,3-alpha-D-glucan synthetase and 1,6-alpha-D-glucan synthetase, were excreted from serotype a, d and g strains. The enzymes of serotype a strains were distinguishable from those of serotypes d and g by differences in their pI values. Serotype c, e and f strains excreted basic glucosyltransferase and acidic fructosyltransferase. Serotype b strains also excreted the glucosyl- and fructosyltransferases, but the pI values were different from those of the enzymes from the other serotypes. Thus, S. mutans strains could be divided into four groups by analytical isoelectric focusing of glycosyltransferases which corresponded well to the four genetic groups.
Glucosyltransferases↗
Comparative anatomical observations on the tongue of the Insectivora.
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Animals↗
Purification and characterization of basic glucosyltransferase from Streptococcus mutans serotype c.
Streptococcus mutans Ingbritt (serotype c) was found to secrete basic glucosyltransferase (sucrose: 1,6-alpha-D-glucan 3-alpha and 6-alpha-glucosyltransferase). The enzyme preparation obtained by ethanol fractionation, DEAE Bio-Gel A chromatography, chromatofocusing and preparative isoelectric focusing was composed of three isozymes with slightly different isoelectric points (pI 8.1-8.4). The molecular weight was estimated to be 151000 by SDS-polyacrylamide gel electrophoresis. The specific activity of the enzyme was 9.8 IU per mg of protein and the optimum pH was 6.5. The enzyme was activated 2.4-fold by commercial dextran T10, and had Km values of 7.1 micro M for the dextran and 4.3 mM for sucrose. Glucan was de novo synthesized from sucrose by the enzyme and found to be 1,6-alpha-D-glucan with 17.7% of 1,3,6-branching structure by a gas-liquid chromatography-mass spectroscopy.
Chromatography, Ion Exchange↗
Direct activity stains for glycosidase and glucosyltransferase after isoelectric focusing in horizontal polyacrylamide gel layers.
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Electrophoresis, Polyacrylamide Gel↗
Purification and properties of Streptococcus mutans extracellular glucosyltransferase.
Extracellular glucosyltransferase (sucrose:1,6-alpha-D-glucan 3-alpha- and 6-alpha-glucosyltransferase) was purified about 10 000-fold from the culture supernatant of Streptococcus mutans 6715. The enzyme preparation was homogeneous on polyacrylamide gel electrophoresis, isoelectric focusing and ultracentrifugation analyses. The specific activity of the enzyme was 34.9 I.U. per mg of protein and the carbohydrate content was less than 1% (w/w). The molecular weight was determined to be 149 000 +/- 5000 by sedimentation equilibrium experiment. The acidic and basic amino acids of the enzyme comprised 29 and 8.4% of total amino acid, respectively, and the isoelectric point was pH 4.1. The enzyme had the optimum pH of 5.5 and the Km value of 2.4 mM for sucrose. The water-soluble glucan, which was de novo-synthesized from sucrose by the purified enzyme, was analyzed by a gas-liquid chromatography-mass spectroscopy and was found to be 1,6-alpha-D-glucan with highly (35%) branched structure of 1,3,6-linked glucose residue.
Amino Acids↗