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Biomedical subjects

A Omori

Publications and source records attributed to A Omori.

At least 73 records · Page 4Linked to original sources
PubMed1991

Purification and determination of the NH2-terminal amino acid sequence of mouse alpha-amylase secreted from Saccharomyces cerevisiae: correct processing of the secretion signal from pGKL killer 28 kDa precursor protein.

We have previously reported the construction of recombinant mouse salivary alpha-amylase secretion vector in Saccharomyces cerevisiae utilizing novel yeast secretion signal derived from killer 28 kDa precursor protein. Here, we have first purified recombinant mouse alpha-amylase to homogeneity from the culture medium of S. cerevisiae, and determined its NH2-terminal amino acid sequence. The sequencing data indicated that the 28 kDa killer secretion signal-alpha-amylase fusion protein was cleaved accurately at its native processing site, and that both the core-glycosylated and non-glycosylated alpha-amylases possessed the same NH2-terminal amino acid sequences.

Amino Acid Sequence↗
PubMed1991

A novel brain-specific 25 kDa protein (p25) is phosphorylated by a Ser/Thr-Pro kinase (TPK II) from tau protein kinase fractions.

A novel brain-specific 25 kDa protein (p25) was purified from a bovine brain extract. The protein was phosphorylated by Ser/Thr-Pro kinase (TPK II) in tau protein kinase fractions at the Ser residues of Ser-Pro sequences. Using immunoblot analysis, the protein was found only in brain extracts, and was most abundant in the brain regions such as cerebrum and hippocampus, but less abundant in cerebellum, medulla oblongata and olfactory bulb. The protein was detected in rat, bovine and human brain extracts, indicating that this protein specifically exists in mammalian brain tissues.

Amino Acid Sequence↗
PubMed1991

A serine/threonine proline kinase activity is included in the tau protein kinase fraction forming a paired helical filament epitope.

Previously we partially purified a novel protein kinase which phosphorylated tau and formed a paired helical filament (PHF) epitope. In this paper we show that the kinase fraction contains a protein kinase activity recognizing serine/threonine proline sequence. The kinase phosphorylated tau at the tau-1 site previously reported as one of the phosphorylation sites on PHF by other groups. The kinase also phosphorylated extraordinarily insoluble portion located on C-terminal region of tau in PHF. It is worth considering that tau phosphorylated by this kinase activity is incorporated into PHF.

Amino Acid Sequence↗
PubMed1991

Conversion of endoglycoceramidase-activator II by trypsin to the 27.9 kDa polypeptide possessing full activity: purification of activator for endoglycoceramidase by trypsin treatment followed by trypsin-inhibitor agarose column application.

Endoglycoceramidase (EGCase) cleaves the linkage between oligosaccharides and ceramides of various glycosphingolipids [Ito, M. & Yamagata, T. (1986) J. Biol. Chem. 261, 14278-14282]. A detergent was required for EGCase to express full activity, possibly due to its hydrophobic nature. Recently, activator proteins responsible for stimulating EGCase activity in the absence of detergents were isolated from the culture supernatant of Rhodococcus sp. [Ito, M., Ikegami, Y., & Yamagata, T. (1991) J. Biol. Chem. 266, 7919-7926]. The activity of activator II specific for EGCase II was heat-labile but insensitive to trypsin-treatment. This activator (69.2 kDa) was converted to the 27.9 kDa polypeptide via the 42 kDa intermediate by exhaustive trypsination, and the stimulatory activity of 27.9 kDa polypeptide on EGCase II was identical to that of the native form toward asialo GM1 and cell-surface GM3 of horse erythrocytes as substrates. This observation was successfully applied to obtain the purified activator without contamination with EGCase activity, which is abolished completely following treatment with trypsin.

Animals↗
PubMed1990

Rat liver arginase suppresses mixed lymphocyte reaction.

An inhibitory factor to mixed lymphocyte reaction (MLR) was purified from the supernatant of rat liver homogenate by procedures including chloroform treatment, ammonium sulfate precipitation, ion-exchange column chromatography, and gel filtration. The molecular weight of the purified inhibitor was 34,000 on SDS-PAGE. We determined the amino acid sequence of the N-terminal region of the purified inhibitor to be Glu-Glu-Pro-Trp-Met-Ser-Met-Ser-Ser-Lys-Pro-Lys-Pro-Ile-Glu-. This sequence shows a high homology to a rat arginase, the amino acid sequence of which was predicted from the nucleic acid sequence of cloned rat arginase cDNA. The amino acid sequence of the purified arginase is 6 amino acid residues longer than the predicted one. The purified MLR inhibitor showed a high arginase activity. The inhibition mechanism was studied and it was discovered that L-arginine was depleted in the culture medium, and that the supply of L-arginine to the cell culture caused recovery of the incorporation of tritium thymidine. Here we present evidence that the MLR inhibitor from rat liver homogenate is the liver arginase. It is noteworthy that immune response may be controlled by a liver factor.

Amino Acid Sequence↗
PubMed1990

Anticonvulsant syndrome with multiple symptoms, including porphyria, IgA deficiency, and liver dysfunction.

A 19-year-old Japanese female who had been treated for epilepsy with a combined phenytoin-phenobarbital preparation for the past three years presented with increasing skin pigmentation and hirsutism. She had suffered two attacks of loss of consciousness after bilateral partial oophorectomy at the age of 16. Investigations revealed a marked increase in coproporphyrin levels in the urine and feces, a marked decrease in her serum IgA level, and liver dysfunction. All these manifestations gradually improved upon the withdrawal of her antiepileptic treatment. In vitro studies revealed B cell dysfunction producing IgA deficiency, which normalized within one year after discontinuation of the antiepileptic therapy. It was assumed that her treatment had worsened preexisting porphyria, which was misdiagnosed as epilepsy because of abnormal EEG findings. The type of porphyria appeared to be hereditary coproporphyria, despite the lack of a family history.

Adult↗
PubMed1990

[Prognostic significance of the DNA ploidy of the early glottic cancer].

The stage classification is most frequently used at the present in predicting the outcome of laryngeal carcinoma. Recently, DNA ploidy pattern as detected by DNA flow cytometry and cytofluorometry has been also shown to be predictive. In this study, DNA cytofluorometry was performed on formalin-fixed paraffin-embedded tissues from 18 patients with T1 and T2 glottic squamous cell carcinoma for whom long-term follow-up data were available. The DNA ploidy pattern was classified into three types, diploid, diploid + tetraploid and aneuploid according to the DNA content of Go/G1 cells and mitotic cells. In these 18 cases, 8 cases (44%) had diploid pattern, 3 cases (17%) had the diploid + tetraploid pattern and 7 cases (39%) had the aneuploid pattern. The ploidy pattern was significantly associated with the relapse-free rate, but did not correlate with the stage of the carcinoma and differentiation of the cancer cells. Distribution of the patients by histology, stage and therapy was almost equal among the diploid, diploid + tetraploid and aneuploid groups. All the patients were treated with irradiation (60Gy). In the group as a whole, no patient died of glottic carcinoma. Relapse-free survival rates for diploid, diploid + tetraploid and aneupoid were 88%, 33% and 29% respectively. This retrospective study of glottic cancer treated with radiation therapy suggests the possibility that the DNA ploidy pattern would significantly predict patient outcome and would be useful for selecting patients whose poor prognosis demands more aggressive therapy.

Aged↗
PubMed1988

Avian myeloblastosis virus reverse transcriptase is easier to use than the Klenow fragment of DNA polymerase I for labeling the 3'-end of a DNA fragment.

The 3'----5' exonuclease activity of the Klenow fragment operates in 3'-end labeling of DNA fragments. In the presence of excess deoxyribonucleoside 5'-triphosphates (dNTPs), the 5'----3' polymerase activity is dominant over the exonuclease activity. However, in the presence of a small amount of dNTPs, the exonuclease activity removed deoxyribonucleoside 5'-monophosphate (dNMP) incorporated in the 3'-end of a DNA strand by the polymerase activity. We found that the radioactivity of incorporated dNMP decreased remarkably in the course of 3'-end labeling by the Klenow fragment. On the other hand avian myeloblastosis virus (AMV) reverse transcriptase also possesses the polymerase activity. The decline of the incorporated radioactivity was not observed, indicating that the enzyme has neither exo- nor endonuclease activities. Furthermore, the level of the incorporated radioactivity was the same as that obtained by the Klenow fragment. We conclude that AMV reverse transcriptase is easier to use than the Klenow fragment for labeling the 3'-end of a DNA fragment.

Affinity Labels↗
PubMed1988

3'-end labeling of DNA fragments by AMV-reverse transcriptase.

The efficiency on 3'-end labeling of DNA fragments was compared between Klenow fragment of DNA polymerase I from E. coli and AMV-reverse transcriptase. In the case of Klenow fragment, the exonuclease activity of this enzyme rapidly removed the labeled dNMP incorporated in 3'-end of DNA fragment by the polymerase activity of it. AMV-reverse transcriptase caused no decrease of the labeled dNMP incorporated by the polymerase activity because it has no exonuclease activity. Therefore, AMV-reverse transcriptase is easier to use than Klenow fragment for labeling the 3'-end of DNA fragment.

Avian Myeloblastosis Virus↗
PubMed1980

Different repeat lengths in rat satellite I DNA containing chromatin and bulk chromatin.

The nucleosome repeat structure of a rat liver chromatin component containing the satellite I DNA (repeat length 370 bp) was investigated. Digestion experiments with micrococcal nuclease, DNAase II, and the Ca2+/Mg2+-dependent endogenous nuclease of rat liver nuclei revealed a repeat unit of 185 nucleotide pairs which is shorter by approximately 10 bp than the repeat unit of the bulk chromatin of this cell type. The difference seems not to be related to the histone composition which was found to be similar in the two types of chromatin.

Animals↗
PubMed1980

Non-random arrangement of nucleosomes in satellite I containing chromatin of rat liver.

The location of nucleosomes on the nucleotide sequence of rat satellite I DNA was investigated using micrococcal nuclease, exonuclease III, and restriction nucleases as tools. Hae III cleaved the satellite DNA containing chromatin very preferentially in the linker region. Nucleosomes were found predominantly in three defined positions on the 370 bp satellite I monomer unit. This type of arrangement occurs on not more than half of the satellite DNA containing chromatin while the rest of this chromatin is arranged differently. The arrangement of nucleosomes with high probability in preferred frames and with low probability in less preferred frames may be a general phenomenon which can be discussed as a possible mechanism to modulate sequence recognition.

Animals↗
PubMed1978

Isolation and some properties of a deoxyribonuclease from Turbo cornutus.

1. Four DNases were found in the dried liver extract of a top shell, Turbo cornutus. The major one was purified 120-fold by phosphocellulose column chromatography, sulfoethylcellulose column chromatography and gel-filtration on Sephadex G-150. The yield was 2.7%. 2. The enzyme activity was not affected by Mg2+ (10(-3)--10(-2)M), EDTA (10(-3)--10(-2)M), or NaCl (10(-1)M). It showed a pH optimum of 4.7--4.8. Ionic strength was found to be critical for the maximal activity. The isoelectric point was 8.5--9.0. On heating at 50 degrees C C for 5 min the enzymic activity fell to half the initial value. 3. The enzyme preparation degraded native as well as heat-denatured DNA, but not RNA. It degraded heat-denatured DNA endonucleolytically to give oligonucleotides with 3'-phosphates. 4. The 3'-phosphate and 5'-hydroxy termini of oligonucleotides were investigated. At both the 3'- and 5'-terminal positions, purine nucleotides were predominant.

Deoxyribonucleases↗
PubMed1978

Isolation and some properties of two deoxyribonucleases from a snail, Achatina fulica.

1. Two main DNases were found in the dried liver extract of a snail, Achatina fulica. They were purified by the phosphocellulose batch method and by phosphocellulose column chromatography. The enzyme eluted earlier from the phosphocellulose column was designated as Achatina DNase-1 and the other as Achatina DNase-2. DNase-1 was purified further by QAE-Sephadex A-25 column chromatography (twice) just before use because of the instability of the purified enzyme. By these procedures, DNase-1 and 2 were purified 200- and 130-fold, respectively. 2. Divalent or monovalent cations had no marked effect on either enzyme. The showed pH optima of 4.8 (DNase-1) and 5.2 (DNase-2). Ionic strength was found to be critical for the maximal activity. The isoelectric points of DNase-1 and 2 were both 6.9. On heating at 70--75 degrees C for 5 min, each enzymic activity fell to half of the initial value. 3. The enzyme preparations degraded native DNA 1.5--2.5 times faster than heat-denatured DNA. They both degraded heat-denatured DNA endonucleolytically, to give oligonucleotides with 3'-phosphates. 4. The 3'-phosphoryl and 5'-hydroxy termini of the resulting oligonucleotides were analyzed. DNase-1 possessed marked specificity for dThd at 3'-termini and dAdo at 5'-termini in the early stages of degradation, but only for dAdo at 5'-termini in the later stages. DNase-2 showed some preference for purine nucleotides at both 3'- and 5'-termini in the later stages of degradation.

Chromatography↗