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H Mukasa

Publications and source records attributed to H Mukasa.

At least 37 records · Page 2Linked to original sources
PubMed1989

Purification and characterization of cell-associated glucosyltransferase synthesizing insoluble glucan from Streptococcus mutans serotype c.

Streptococcus mutans Ingbritt (serotype c) was shown to have a significant amount of cell-associated glucosyltransferase activity which synthesizes water-insoluble glucan from sucrose. The enzyme was extracted from the washed cells with SDS, renatured with Triton X-100, adsorbed to 1,3-alpha-D-glucan gel, and then eluted with SDS. The enzyme preparation was electrophoretically homogeneous, and the specific activity was 7.3 i.u. (mg protein)-1. The enzyme had an Mr of 158,000 as determined by SDS-PAGE, and was a strongly hydrophilic protein, as judged by its amino acid composition. The enzyme gradually aggregated in the absence of SDS. The enzyme had an optimum pH of 6.5 and a Km value of 16.3 mm for sucrose. Activity was stimulated 1.7-fold by dextran T10, but was not stimulated by high concentrations of ammonium sulphate. Below a sodium phosphate buffer concentration of 50 mm, activity was reduced by 75%. This enzyme synthesized an insoluble D-glucan consisting of 76 mol% 1,3-alpha-linked glucose and 24 mol% 1,6-alpha-linked glucose.

Bacterial Proteins↗
PubMed1988

Frontal midline theta activity and platelet MAO in human subjects.

The distinctive theta rhythm that appears at the frontal midline during the performance of mental tasks has been designated as frontal midline theta (Fm theta). Fm theta shows individual differences and seems to be related to certain personality traits. In several studies, it has been indicated that low platelet monoamine oxidase (MAO) activity is also associated with certain personality traits. In the present study, we found a negative correlation between the appearance of Fm theta and platelet MAO activity. Subjects with marked extroversion show a high amount of Fm theta and low MAO activity. It is therefore suggested that Fm theta, an electrophysiological marker, may be useful in the investigation of monoamine functions in the central nervous system (CNS) by way of platelet MAO activity, a biochemical marker.

Adult↗
PubMed1988

Streptococcus mutans gtfA gene specifies sucrose phosphorylase.

The ethanol-insoluble product formed from sucrose by purified enzyme encoded by the gtfA gene from Streptococcus mutans, expressed in recombinant Escherichia coli, was analyzed by 13C and 31P nuclear magnetic resonance. The product was identified as alpha-D-glucose-1-phosphate, and it was concluded that the GTF-A enzyme is sucrose phosphorylase (sucrose:orthophosphate alpha-D-glucosyltransferase [EC 2.4.1.7]).

DNA, Bacterial↗
PubMed1987

Characterization of glucosyltransferase expressed from a Streptococcus sobrinus gene cloned in Escherichia coli.

The gene encoding a glucosyltransferase which synthesized water-insoluble glucan, gtfI, previously cloned from Streptococcus sobrinus strain MFe28 (mutans serotype h) into a bacteriophage lambda vector, was subcloned into the plasmid pBR322. The recombinant plasmid was stable in Escherichia coli and gtfI was efficiently expressed. The GTF-I expressed in E. coli was compared to the corresponding enzymes in S. sobrinus strains MFe28 (serotype h), B13 (serotype d) and 6715 (serotype g) and shown to resemble them closely in molecular mass and isoelectric point. The insoluble glucan produced by GTF-I from recombinant E. coli consisted of 1,3-alpha-D-glycosyl residues (approximately 90%). An internal fragment of the gtfI gene was used as a probe in hybridization experiments to demonstrate the presence of homologous sequences in chromosomal DNA of other streptococci of the mutans group.

Cloning, Molecular↗
PubMed1987

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↗
PubMed1987

Individual differences in psychophysiological responses after alcohol ingestion.

We have conducted a study on the individual differences in psychophysiological responses to alcohol. The subjects were 12 flushers and 12 non-flushers. In the flushers, significant increases in the blood acetaldehyde (AcH) level, skin temperature and pulse rate were found. In the non-flushers, on the contrary, no significant increase was observed. There was no difference between the flushers and the non-flushers concerning the change in the blood ethanol (EtOH) level nor the change of P1 and P2 latencies in photopalpebral reflex (PPR). Also, no difference was found in the change of the state anxiety level. From these results, we concluded that there exists an obvious discrepancy between the central inhibitory response (elicited by EtOH) and the autonomic response (elicited by AcH) of the human subjects to a small amount of alcohol.

Acetaldehyde↗
PubMed1987

[Effect of the TRH analog DN-1417 on the appearance of frontal midline theta activity (Fm0)].

The distinct 0 rhythm which appears in the frontal midline area during the performance of mental tasks is called Fm0. The appearance of Fm0 shows individual differences and a close relationship to the personality traits of the subject. It is also reported that administration of diazepam or alcohol brings about an increase of Fm0 along with lowering of the anxiety level. In the present study, the TRH analog DN-1417 (80 mg) was administered to 8 healthy male students for 15 days. They were all extrovert in nature and had no great neurotic tendencies as measured by the Maudsley Personality Inventory (MPI). EEG recording, determination of the blood concentration of DN-1417, and Spielberger's State-Trait Anxiety Inventory-I (STAI-I) were carried out before, during, and after drug administration. The appearance of Fm0 showed significant increase during and just after drug administration. As to anxiety, the STAI-I score showed no significant change. There was no correlation between blood concentration and Fm0. From these results, we considered that the change of appearance of Fm0 due to drug administration was not necessarily associated with change of the anxiety level, and that DN-1417, a DA releaser, increased the appearance of Fm0.

Adult↗
PubMed1985

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↗
PubMed1985

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↗
PubMed1985

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↗
PubMed1983

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↗
PubMed1983

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↗
PubMed1983

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↗
PubMed1982

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↗