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Y Inoue

Publications and source records attributed to Y Inoue.

At least 1,333 records · Page 74Linked to original sources
PubMed1992

[Three-dimensional display of 99mTc-MIBI myocardial scintigraphy].

One of 99mTc-hexakis, 99mTc-methoxyisobutyl isonitrile (MIBI), has been demonstrated to have a myocardial uptake proportional to regional coronary blood flow. In this study, 99mTc-MIBI myocardial scintigraphy were performed for 16 patients with ischemic heart disease. After injection of 740 MBq of 99mTc-MIBI, 64 projection images were collected during a 360-degree rotation. Three-dimensional (3D) display of the left ventricle was reconstructed with depth-shading method from 99mTc-MIBI SPECT images, which were reconstructed by filtered back projection method. In 9 of the patients, left ventricular cineangiography were performed as diagnostic gold standard. Four physicians blinded to patients' clinical informations interpreted 3D images and SPECT images on separate occasions. Diagnosis of hypoperfusion by 3D displays agreed with those of SPECT in 92.9% (104/112 segments), and disagreed in 7.1% (8 segments). Sensitivity and specificity of 3D images were 87.0 and 93.9%, which were not statistically different (p less than 0.05) from that of SPECT images (91.3, 97.0%). Receiver operating characteristic (ROC) analysis revealed nearly identical curves for the two. Although 3D display had nearly identical diagnostic ability with SPECT, observers reported that 3D images were easier to diagnose than SPECT images. An advantage of the 3D display is that the display gives a more realistic impression of the left ventricle to an observer than tomography or planar imaging. Another advantage is that 3D display can reduce the amount of data storage compared with that of SPECT. In conclusion, 3D images may be useful for diagnosis of hypoperfusion of left ventricle.

Adult↗
PubMed1991

Peptide:N-glycosidase activity found in the early embryos of Oryzias latipes (Medaka fish). The first demonstration of the occurrence of peptide:N-glycosidase in animal cells and its implication for the presence of a de-N-glycosylation system in living organisms.

The recent discovery of free oligosaccharides typical for the complex type of glycan chains terminating with a free di-N-acetylchitobiosyl structure in certain fish eggs and early embryos (Ishii, K., Iwasaki, M., Inoue, S., Kenny, P. T. M., Komura, H., and Inoue, Y. (1989) J. Biol. Chem. 264, 1623-1630; Seko, A., Kitajima, K., Iwasaki, M., Inoue, S., and Inoue, Y. (1989) J. Biol. Chem. 264, 15922-15929; Inoue, S., Iwasaki, M., Ishii, K., Kitajima, K., and Inoue, Y. (1989) J. Biol. Chem. 264, 18520-18526) led us to find an enzyme responsible for detachment of N-linked glycan chains from glycoproteins by hydrolyzing the beta-aspartyl-glucosylamine linkage in Oryzias latipes embryos. The enzyme, peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase or peptide:N-glycosidase (PNGase), was partially (2090-fold) purified, and the reaction site at which this enzyme acts was specified by analysis and identification of the reaction products. This is the first demonstration showing PNGase in animal sources, although the presence of PNGases was reported in a variety of plant extracts and bacteria. Thus, the commonality of this type of enzyme is now demonstrated, and the possible physiological role of PNGase in de-N-glycosylation as a basic biologic process is proposed.

Amidohydrolases↗
PubMed1991

Isolation and structural elucidation of a novel type of ganglioside, deaminated neuraminic acid (KDN)-containing glycosphingolipid, from rainbow trout sperm. The first example of the natural occurrence of KDN-ganglioside, (KDN)GM3.

Rainbow trout sperm contained almost exclusively monoanionic ganglioside fraction as a major acidic glycosphingolipid. Two monoacidic gangliosides were isolated and purified in this study and designated as sperm ganglioside 1 and 2 (sg-1 and sg-2). The two gangliosides, sg-1 and sg-2, contained the same neutral sugars, galactose and glucose in molar ratio of 1:1 and no GalNAc except for the presence of N-acetyl-neuraminic acid (NeuAc) in sg-1 and deaminated neuraminic acid (KDN; 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid) in sg-2. The complete structures of these gangliosides were determined by a combination of methylation analysis, fast atom bombardment mass spectrometry, 400-MHz one- and two-dimensional 1H nuclear magnetic resonance spectroscopy, fatty acid analysis, and endoglycoceramidase digestion NeuAc alpha 2----3Gal beta 1----4Glc beta 1----Cer sg-1 [(NeuAc)GM3] KDN alpha 2----3Gal beta 1----4Glc beta 1----Cer sg-2 [(KDN)GM3] where, for both sg-1 and sg-2, the ceramide moieties (Cer) were found to be made up of 4-sphingenine and mainly C16:0 fatty acid (palmitate; 95%) with a minor amount of C24:1 fatty acyl chain (nervonate, 5%). The structure of sg-2 is novel and represents the first example of a new class of gangliosides, i.e. KDN-gangliosides.

Animals↗
PubMed1991

Identification of free glycan chain liberated by de-N-glycosylation of the cortical alveolar glycopolyprotein (hyosophorin) during early embryogenesis of the Medaka fish, Oryzias latipes.

In Medaka embryos (at the stages of blastulation to organogenesis), we found the presence of free glycan of which structure is identical with the multiantennary N-linked sugar chain of L-hyosophorin molecules which were originally present in the cortical alveoli of the unfertilized eggs in their precursor high molecular form. The free glycan-enriched fraction was separated from L-hyosophorin by chromatography on DEAE-Sephadex A-25 and Sephadex G-50 after removal of the sialic acid residues with exo-sialidase. Composition analysis, 400-MHz 1H NMR spectroscopy, and pyridylamination-hydrazinolysis-nitrous acid deamination of the free glycan showed the presence of di-N-acetylchitobiosyl structure at the reducing end, suggesting that the free glycan chain was derived from L-hyosophorin by the action of a specific peptide:N-glycosidase (PNGase). When we combine the previous finding of the hyosophorin-derived unique pentaantennary free glycan chain in the flounder embryos [A. Seko et al. (1989) J. Biol. Chem. 264, 15922-15929], it is anticipated that PNGase-catalyzed de-N-glycosylation of L-hyosophorin would be required at a certain stage of embryogenesis for L-hyosophorin to play a yet undefined functional role during early development.

Amino Acid Sequence↗
PubMed1991

Purification and cDNA cloning of rat 6-pyruvoyl-tetrahydropterin synthase.

6-Pyruvoyl-tetrahydropterin synthase, which catalyzes the second step in the biosynthesis of tetrahydrobiopterin, was purified approximately 18,000-fold to apparent homogeneity from rat liver. The molecular mass of the native enzyme was estimated to be 83 kDa by gel filtration. The enzyme showed a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis corresponding to a molecular mass of 17 kDa. Up to 24 residues of the NH2-terminal sequence were determined by Edman degradation, which released a single amino acid at each step. These results indicate that the enzyme consists of identical subunits. The purified enzyme was digested with lysyl endopeptidase or V8 protease, and 11 peptide fragments were isolated. On the basis of the sequences of these peptides, oligonucleotides were synthesized and used to screen a rat liver cDNA library, and one cDNA clone was isolated. The complete nucleotide sequence of the 1176-base pair cDNA was then determined. The deduced amino acid sequence contained 144 amino acid residues, but a NH2-terminal four-amino acid sequence was not found in the purified protein. Therefore, the mature protein consists of 140 amino acids. A single mRNA band of 1.3 kilobases was obtained by RNA blot analysis of rat liver. The predicted amino acid sequence of 6-pyruvoyl-tetrahydropterin synthase was compared with the Protein Sequence Database of the National Biomedical Research Foundation, revealing significant local similarity to large T antigens from the polyomavirus family.

Alcohol Oxidoreductases↗
PubMed1991

ELISA using monoclonal antibody to human serum arylesterase.

ELISA for determining arylesterase content in human serum has been developed by the one-step sandwich method using 2 monoclonal antibodies. While the content of arylesterase in healthy adults was 81 +/- 25 mg/l, a decrease was observed in patients with liver cirrhosis, where the mean +/- SD was 37 +/- 7 mg/l. ELISA of human serum arylesterase correlated with the activity determined by a specific substrate assay we devised recently.

Adult↗
PubMed1991

The intracortical position of pyramidal tract neurons in the motor cortex of the reeler changes from postnatal day 10 to adulthood.

To determine whether or not the intracortical distribution pattern of pyramidal tract (PT) neurons in the motor cortex (hindlimb area) of normal and reeler mutant mice changes during early postnatal development of the cortex, we injected HRP into the pyramidal decussation of postnatal day (P) 8 and adult animals of the normal and reeler strains, and killed the animals 2 days later. In the normal P10 and adult mice, such an injection resulted in a band of labelled neurons confined to the layer of large pyramids (LP), suggesting that the intracortical localization of PT neurons does not change from P10 to adulthood in the normal strain. In the P10 and adult reeler mice, labelled PT neurons were scattered radially from the deepest zone to the superficial zone of the motor cortex. However, while the HRP-labelled PT neurons are located bilaminarly in both the deepest zone and the superficial zone of the motor cortex of the P10 reeler mouse, the majority of PT neurons were found in the upper third of the motor cortex of the adult reeler mouse. Thus, the intracortical distribution pattern of PT neurons of the reeler mouse changes during the postnatal period.

Animals↗
PubMed1991

Identities of four low-molecular-mass subunits of the photosystem I complex from Anabaena variabilis ATCC 29413. Evidence for the presence of the psaI gene product in a cyanobacterial complex.

Photosystem I (PSI) complex of Anabaena variabilis ATCC 29413 consists of at least 11 subunits, 9 of which are resolved by high resolution gel electrophoresis. N-terminal amino acid sequences of the four subunits with molecular masses of 6.8, 5.2, 4.8 and 3.5 kDa were determined. Based on the sequence homology, the 3.5 kDa subunit was revealed to correspond to PSI-I (the gene product of psaI), which had so far been detected only in higher plant PSI complexes. The 6.8 kDa protein and 4.8 kDa protein were identified as gene products of psaK and psaJ, respectively. The 5.2 kDa protein was homologous to a 4.8 kDa subunit of PSI of the thermophilic cyanobacterium Synechococcus vulcanus, suggesting that this protein is a component of PSI in cyanobacteria.

Amino Acid Sequence↗
PubMed1991

Structural and functional modifications of the manganese cluster in Ca(2+)-depleted S1 and S2 states: electron paramagnetic resonance and X-ray absorption spectroscopy studies.

The effect of extraction of weakly bound Ca2+ by low-pH treatment on the O2-evolving apparatus was studied by use of low-temperature electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy. In low-pH-treated PSII membranes, an S2 EPR multiline signal with modified line shape was induced by illumination at 0 degrees C, but its signal amplitude decreased upon lowering the excitation temperature with concomitant oxidation of cytochrome (cyt) b-559 in place of Mn. The half-inhibition temperature for formation of the modified multiline signal was found at -33 degrees C, which was much higher than that for formation of the normal S2 state in untreated control membranes. Signal IIf was normally induced down to -30 degrees C, but its dependence on excitation temperature was different from that for modified S2. This was interpreted as indicating that the low-temperature blockage of modified S2 formation is due to the incapability of electron abstraction from the Mn cluster. The Mn K-edge of X-ray absorption near-edge structure (XANES) spectrum shifted to lower energy by 0.8 eV after low-pH treatment, but the shift was reversed by addition of Ca2+. Upon illumination at 0 degrees C of treated membranes, the K-edge energy was up-shifted by 0.8 eV, but was not upon illumination at 210 K. These results were interpreted as indicating that extraction of weakly bound Ca2+ by low-pH treatment gives rise to structural and functional modulations of the Mn cluster.

Calcium↗
PubMed1991

A possible role of redox-active histidine in the photoligation of manganese into a photosynthetic O2-evolving enzyme.

Our previous experiments with a histidine modifier suggest that in Mn-depleted photosystem (PS) II a histidine residue is photooxidized and charge recombination between the oxidized histidine and QA-emits the thermoluminescence AT-band [Ono, T., & Inoue, Y. (1991) FEBS Lett. 278, 183-186]. By use of the AT-band as an index for histidine oxidation, and EPR signals IIf and IIs as indexes for tyrosine oxidation, we studied the role of this putative redox-active histidine in the photoactivation of the O2-evolving enzyme in NH2OH-treated PSII. The following results have been obtained. (i) Strong-light photoinhibition of NH2OH-treated PSII quickly impaired both capabilities of photoactivation and AT-band emission with almost the same half-inhibition time of 1-2 s, while signal IIf was well retained and signal IIs was not affected at all after complete loss of photoactivation capability. (ii) The capability of exogenous Mn2+ photooxidation was relatively sensitive to strong-light photoinhibition, but DPC was relatively sensitive to strong-light photoinhibition, but DPC photooxidation was highly resistant. (iii) Weak-light photoinhibition simultaneously impaired the capabilities of photoactivation, AT-band emission, and signal IIf with the same half-inhibition time of 1 min, leaving signal IIs unaffected. (iv) It was inferred that the putative redox-active histidine is essential for the photooxidation of coordinated Mn2+, the probable initial step of photoactivation, and its photodamage results in the loss of the capabilities of photoactivation and AT-band emission. Based on these, a scheme of electron transfer on the donor side of PSII involving histidine oxidation via Z+ is proposed.

2,6-Dichloroindophenol↗
PubMed1991

Cloning of the psbK gene from Synechocystis sp. PCC 6803 and characterization of photosystem II in mutants lacking PSII-K.

We cloned and sequenced the psbK gene, coding for a small photosystem II component (PSII-K), from the transformable cyanobacterium, Synechocystis sp. PCC 6803, and determined the N-terminal sequence of mature PSII-K. The psbK gene product is processed by cleaving off eight amino acid residues from the N terminus. A mutant lacking psbK was constructed; this mutant grew photoautotrophically, but its growth rate was reduced. The number of photosystem II reaction centers on a chlorophyll basis was decreased by less than a factor of 2 in the psbK-deletion mutant. In Synechocystis sp. PCC 6803, the psbK gene is transcribed as a single gene and is not part of an operon. Single-site mutations were introduced into psbK leading to early termination or deletion of the presequence. The phenotype of these mutants strongly resembles that of the psbK deletion mutant, indicating that indeed the change in phenotype in the deletion mutant is directly correlated with PSII-K. PSII-K is not essential for photosystem II assembly or activity but is needed for optimal photosystem II function.

Amino Acid Sequence↗
PubMed1991

Enhancement by chloride ions of photoactivation of oxygen evolution in manganese-depleted photosystem II membranes.

The Mn cluster that catalyzes photosynthetic oxygen evolution was removed from the photosystem II (PSII) complex by treating PSII membranes with 1.0 mM NH2OH with concomitant inactivation of oxygen evolution. The cluster was reconstituted by incubating the treated membranes with 1.0 mM Mn2+, 20 mM Ca2+, 10 microM 2,6-dichlorophenolindophenol, and Cl- under illumination with continuous or flashing light to restore the oxygen-evolving capacity. This light-dependent activation (photoactivation) of oxygen evolution did not occur to a significant extent at 3 mM Cl-, but markedly accelerated at higher Cl- concentrations without showing a saturation phenomenon even at 1 M Cl-. At 10 mM Cl- only about 10% of the oxygen-evolving activity before NH2OH treatment was restored by 5-min illumination with continuous light, whereas at 600 mM Cl- about 60% of the original activity was recovered. This acceleration resulted from at least two different actions of Cl-: (1) stabilization of the intermediate state involved in the photoactivation process and (2) increase in the quantum yield of photoactivation. The stabilization of the intermediate was saturated at about 150 mM Cl-, whereas the increase in yield did not show saturation. The Cl(-)-induced increase in quantum yield did not involve any changes in the affinity of either Mn2+ binding or Ca2+ binding for photoactivation, but was rather ascribed to a protective effect of Cl- against inhibition of photoactivation by high concentrations of Mn2+. We also found that removal of the extrinsic 33-kDa protein from the PSII complex increased the Cl- requirement for photoactivation.

Binding Sites↗
PubMed1991

Two new components of 9 and 14 kDa from spinach photosystem I complex.

Two formerly-uncharacterized subunits of 9 kDa and 14 kDa were found in spinach PSI complex. The 9 kDa subunit was released upon removal of antenna chlorophyll complex, whereas the 14 kDa subunit was tightly bound to the core complex. We determined the N-terminal amino acid sequence of the 9 kDa, and an internal sequence of the 14 kDa subunit after protease treatment, since the N-terminus of the latter protein was blocked. These partial sequences suggested that both subunits are new PSI components.

Amino Acid Sequence↗
PubMed1991

Biochemical evidence for histidine oxidation in photosystem II depleted of the Mn-cluster for O2-evolution.

Flash excitation of Tris-treated photosystem II (PSII) membranes generated a thermoluminescence band peaking at -20 degrees C, indicating that a positively charged oxidizing equivalent is stably accumulated on donor side of PSII even in the absence of the Mn-cluster. This oxidizing equivalent was sensitive to low concentrations of exogenous Mn2+, and its stable accumulation was reversibly inhibited by diethylpyrocarbonate treatment that modifies histidine residues with high specificity. It was inferred that there is a photooxidizable histidine residue(s) on donor side of PSII and it provides a redox-active ligand for Mn.

Diethyl Pyrocarbonate↗
PubMed1991

Cloning and sequencing of cDNA encoding rat GTP cyclohydrolase I. The first enzyme of the tetrahydrobiopterin biosynthetic pathway.

A full-length cDNA clone for GTP cyclohydrolase I, the first enzyme of the tetrahydrobiopterin biosynthetic pathway, was isolated and characterized. Synthetic oligonucleotides, constructed according to selected amino acid sequences of purified GTP cyclohydrolase I, were used to screen a rat liver cDNA library. Four clones were isolated, and the length of the longest cDNA insert was 1024 base pairs. The identity of the cDNA was confirmed by amino acid sequence data for eight fragments obtained by lysyl endopeptidase digestion of the purified protein. The coding region encoded a protein of 241 amino acid residues, but the NH2 terminus of the protein contained 11 additional amino acid residues not present in the purified protein. RNA blot analysis showed a single mRNA species of 1.2 kilobases in rat liver. A characteristic feature of the deduced amino acid sequence of GTP cyclohydrolase I was the presence of sequences similar to those proposed for the phosphorylation sites for casein kinase II and growth-associated histone H1 kinase. Furthermore, significant similarity was found to the highly conserved sequences of dihydrofolate reductases, which are known to be involved in the binding of the pterin group of dihydrofolate to the reductases. This region in GTP cyclohydrolase I may be assigned to the binding site of tetrahydrobiopterin, one of the inhibitors of this enzyme.

Amino Acid Sequence↗
PubMed1991

Abnormal fatty acid metabolism in patients in hopantenate therapy during clinical episodes.

Calcium 4-(2,4-dihydroxy-3,3-dimethylbutyramido)butyrate hemihydrate (hopantenate), a cerebral metabolic enhancer used in Japan since 1978, is a homologue of pantothenic acid. Using mass spectrometry, we found urinary excretion of 4-hydroxydodecanedioic acid, 4-hydroxytetradecanedioic acid and a series of 2-hydroxydicarboxylic acids (C8-C14), in addition to a series of odd- and even-numbered dicarboxylic acids (C5-C12) and 3-hydroxydicarboxylic acids (C8-C14) in patients receiving hopantenate during episodes of Reye's-like syndrome. Our findings suggest that an acute intoxication associated with hopantenate occurs owing to pantothenic acid deficiency or the inhibition of CoA-requiring reactions during stress, i.e. infection, prolonged fasting, or malnutrition.

Acids↗