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M Kurono

Publications and source records attributed to M Kurono.

At least 55 records · Page 3Linked to original sources
PubMed1988

Structural analyses of asparagine-linked oligosaccharides of porcine pancreatic kallikrein.

The structures of asparagine-linked oligosaccharides of porcine pancreatic beta-kallikrein are reported. Asparagine-linked neutral oligosaccharides were released by N-oligosaccharide glycopeptidase digestion, and the reducing ends of the oligosaccharides were derivatized with a fluorescent reagent, 2-aminopyridine. The mixture of pyridylamino oligosaccharides was separated by reverse-phase and amide-adsorption high-performance liquid chromatography. The pyridylamino oligosaccharides were separated into more than 50 kinds of oligosaccharides. The structures of 5 kinds of triantennary and 12 kinds of tetraantennary oligosaccharides were determined by the use of high-resolution proton nuclear magnetic resonance spectroscopy and methylation analysis. Furthermore, the structures of five kinds of oligomannose-type oligosaccharides were elucidated by a combination of exoglycosidase digestion and high-performance liquid chromatography. 1H NMR data for 14 out of the 17 kinds of N-acetyllactosamine-type oligosaccharides reported here have not previously been described in the literature. (1) It has been shown that fucose containing tri- and tetraantennary oligosaccharides is predominant in porcine pancreatic beta-kallikrein B. (2) It has also been shown that the heterogeneity of the structure in these types of oligosaccharides is derived from the variety of the positions of galactose residues linked to outer N-acetylglucosamine residues. (3) The distribution of oligosaccharides into two glycosylation sites, asparagine-95 and asparagine-239, of beta-kallikrein B was determined. It has been found that oligomannose-type oligosaccharides are exclusively present at asparagine-239, although N-acetyllactosamine-type oligosaccharides occur at both glycosylation sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Analyses of N-linked oligosaccharides using a two-dimensional mapping technique.

We propose a two-dimensional sugar map method for the simple, reproducible, and sensitive analysis of the structures of N-linked oligosaccharides. The structure of an unknown oligosaccharide can be characterized from its position on the map. The data base for the sugar map is prepared by the use of 113 kinds of standard oligosaccharides, 58 of whose structures have been confirmed by 1H NMR spectroscopy. The present method involves six steps, (i) preparation of oligosaccharides from glycopeptides by N-oligosaccharide glycopeptidase (almond) digestion, (ii) derivatization of the reducing ends of oligosaccharides with a fluorescent reagent, 2-amino-pyridine, by using sodium cyanoborohydride, (iii) separation of oligosaccharide derivatives by high-performance liquid chromatography with an ODS-silica column, (iv) analysis of the size of each separated oligosaccharide on an amide-silica column, (v) plotting of the elution position of a sample on the two-dimensional sugar map obtained for the standard oligosaccharides, and (vi) structural analysis of the oligosaccharides by a combination of sequential exoglycosidase digestion and the steps (iii-v). The present method was applied to the identification of the structures of oligosaccharides in hen ovalbumin. It was found that two unusual oligosaccharides that have not yet been reported exist in ovalbumin.

Animals↗
PubMed1987

Effects of compounds related to beta-hydroxyglutamic acid (BHGA) on identifiable giant neurones of an African giant snail (Achatina fulica Férussac).

The present study aimed to further elucidate the pharmacological features, with respect to sensitivity to L-BHGA agonists, of the receptors sensitive to beta-hydroxy-L-glutamic acid (L-BHGA) in five Achatina giant neurones: PON (periodically oscillating neurone), d-RPLN (dorsal-right parietal large neurone), VIN (visceral intermittently firing neurone), RAPN (right anterior pallial neurone) and v-RCDN (ventral-right cerebral distinct neurone). Of these neurones, d-RPLN and RAPN were depolarized by L-BHGA, while PON, VIN and v-RCDN were inhibited. Threo-beta-hydroxy-DL-aspartic acid markedly depolarized d-RPLN and RAPN (effective potency quotient (EPQ) in relation to the more effective L-BHGA isomer: 1 for d-RPLN and 0.3 for RAPN). This compound produced only slight inhibitory effects on PON, VIN and v-RCDN with EPQs calculated to be less than 0.03, less than 0.03 and 0.03, respectively. On the other hand, erythro-beta-hydroxy-DL-aspartic acid at 10(-3) M was almost ineffective, except on v-RCDN where it elicited some slight inhibitory effects (EPQ: 0.01). L-Aspartic and D-aspartic acid at 10(-3) M, also had almost no effect except for slight effects of D-aspartic acid on d-RPLN (EPQ: 0.1). N-Methyl-L- and N-methyl-D-aspartic acid were slightly effective only on v-RCDN (EPQ: less than 0.01 and 0.01, respectively). The other compounds, including beta-hydroxypyrroglutamic acid (cyclic BHGA) and proline derivatives, were almost ineffective at 10(-3) M; very weak effects were occasionally observed on some neurones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Sequence of an intestinal cDNA encoding human motilin precursor.

A cDNA clone encoding the human motilin precursor was isolated from an intestinal library using synthetic oligonucleotide probes. The predicted amino acid sequence indicates that the motilin precursor consists of 115 amino acids and includes a 25-residue N-terminal signal peptide followed by the 22-amino-acid motilin sequence and a long, 68-residue C-terminal peptide. The amino acid sequence of human motilin predicted from the cDNA sequence is identical to its porcine counterpart, which has been determined by protein sequencing. Proteolytic processing of promotilin to motilin occurs at the sequence, Lys-Lys, this being the first reported instance of processing occurring at a pair of Lys residues. In other precursors it occurs at Lys-Arg, Arg-Arg, Arg, or very rarely Lys.

Amino Acid Sequence↗
PubMed1987

Interaction of dimers of inactive enkephalin fragments with mu opiate receptors.

Dimeric analogues of the inactive enkephalin fragment Tyr-D-Ala-Gly were synthesized by cross-linking with alkanediamine at the C-terminus. Biological evaluation of these dimers (H-Tyr-D-Ala-Gly-NH)2.(-CH2-)n (DTREn), where n = 0-6, revealed that the fragment inactive for mu receptors was activated by its dimerization, with the maximum activation found with DTRE2, and that the dimer was highly mu-selective. So-called "handicapped" dimers, which lack one of the essential groupings required for enkephalin activity, were found to be far less active, indicating that the dimer interacts bivalently with mu receptors. It seems, therefore, that mu opiate receptors contain at least two equivalent binding sites which are extremely close to each other.

Animals↗
PubMed1987

Structural analysis of N-linked oligosaccharides by a combination of glycopeptidase, exoglycosidases, and high-performance liquid chromatography.

A simple, sensitive, and rapid method for the analysis of structures of N-linked carbohydrates is reported. The method involves four steps: preparation of carbohydrate chains from glycopeptides by N-oligosaccharide glycopeptidase digestion; derivatization of the reducing ends of carbohydrate chains with a fluorescent reagent, 2-aminopyridine, by using sodium cyanoborohydride; separation of oligosaccharide derivatives by reverse-phase high-performance liquid chromatography; and structural analysis of oligosaccharides by sequential exoglycosidase digestion. The elution positions of 50 standard oligosaccharide derivatives were determined by HPLC. The structure of an unknown oligosaccharide can be characterized by comparison of its elution position with those of the standard compounds. The method was applied to elucidate the structures of oligosaccharides in the myeloma IgG protein, Yot.

Amidohydrolases↗
PubMed1987

Sequence of an intestinal cDNA encoding human gastric inhibitory polypeptide precursor.

Gastric inhibitory polypeptide (GIP) is a 42-amino acid hormone that stimulates insulin secretion in the presence of glucose. Complementary DNA clones encoding human GIP were isolated from a library prepared with RNA from duodenum. The predicted amino acid sequence indicates that GIP is derived by proteolytic processing of a 153-residue precursor, preproGIP. The GIP moiety is flanked by polypeptide segments of 51 and 60 amino acids at its NH2 and COOH termini, respectively. The former includes a signal peptide of about 21 residues and an NH2-terminal propeptide of 30 amino acids. GIP is released from the precursor by processing at single arginine residues. There is a region of nine amino acids in the COOH-terminal propeptide of the GIP precursor that has partial homology with a portion of chromogranin A as well as pancreastatin.

Amino Acid Sequence↗
PubMed1986

Presence of endogenous calcium ion and its functional and structural regulation in horseradish peroxidase.

The endogenous calcium ion (Ca2+) in horseradish peroxidase (HRP) was removed to cause substantial changes in the proton NMR spectra of the enzyme in various oxidation/spin states. The spectral changes were interpreted as arising from the substantial alterations in the heme environments, most likely the heme proximal and distal sides. The comparative kinetic and redox studies revealed that these conformational changes affect the reduction process of compound II, resulting in the decrease of the enzymatic activity of HRP. It is also revealed from the ESR spectrum and the temperature dependences of the NMR and optical absorption spectra of the Ca2+-free enzyme that the heme iron atom of the Ca2+-free enzyme is in a thermal spin mixing between ferric high and low spin states, in contrast to that of the native enzyme. These results show that Ca2+ functions in maintaining the protein structure in the heme environments as well as the spin state of the heme iron, in favor of the enzymatic activity of HRP.

Calcium↗
PubMed1986

Presence of endogenous calcium ion in horseradish peroxidase. Elucidation of metal-binding site by substitutions of divalent and lanthanide ions for calcium and use of metal-induced NMR (1H and 113Cd) resonances.

Some divalent (Cd2+, Sr2+, Ba2+) and lanthanide (Ln3+) ions can be substituted for endogenous Ca2+ of horseradish peroxidase (HRP, Ca2+-bound hemoenzyme) and maintain the protein structure in the heme vicinity as well as the enzymatic activity of HRP, as does Ca2+. However, due to lower affinity than Ca2+, the bound Ln3+ was readily replaced by Ca2+ to yield native HRP, in sharp contrast to other typical Ca2+-binding proteins, of which the affinity to Ln3+ is higher than to Ca2+. Addition of paramagnetic Ln3+ to Ca2+-free HRP induced a series of paramagnetically shifted 1H NMR resonances of protein at the first metal binding site in HRP. The pH-dependent spectral changes of the Ln3+-shifted resonances suggest that tyrosyl hydroxyl and glutamate and aspartate carboxyl groups are involved in the binding site of the Ca2+, other divalent ions, or Ln3+. The 113Cd NMR spectra of 113Cd2+-bound HRP also indicated the presence of one metal strongly bound to the oxygen ligands and another site with low affinity for the metal ions, which is consistent with the results from the Ln3+-induced proton NMR. All these results suggest that the binding of one metal ion to HRP is essential for its structural and functional properties.

Amino Acids↗
PubMed1986

Opiate receptor binding characteristics of dimeric analogues of mu-selective DAGO-enkephalin.

DAGO-enkephalin ([ D-Ala2, MePhe4, Gly-ol5]enkephalin), a highly selective ligand for mu opiate receptors, was dimerized with a series of alpha,omega-alkanedioic acids (n = 2-12) at the OH-terminus. In the radioligand receptor binding assays with rat brain, most of the DAGO-enkephalin dimers with cross-linking methylene chain n (DEDn) were more potent than DAGO monomer. For delta receptors, affinity of DEDn was maximized with n = 8, which might be related to an optimal distance between two binding sites. For mu receptors, an increase in chain length resulted in a progressive loss of potency. Although all of DEDn are considerably mu-selective, with a mu/delta ratio of 15-50, DEDn exhibited fairly flat binding curves with 15-50% smaller sloped than that of DAGO, suggesting that the dimers interact more strongly with one of the possible two mu binding sites.

Animals↗
PubMed1985

Modification of acyl-plasmin-streptokinase complex with polyethylene glycol. Reduction of sensitivity to neutralizing antibody.

Acyl-plasmin-streptokinase complex has advantages as a 'site' directed fibrinolytic agent with the active site protected from the plasma protease inhibitors. But, in clinical use, the fibrinolytic potential of this acyl-enzyme complex is modified or abolished by the presence of streptokinase antibodies in the patients. Therefore, better therapeutic agents are required. In this work, chemical modification of the acyl-plasmin-streptokinase complex with polyethylene glycol was found to result in marked resistance to neutralization with streptokinase antibodies.

Antibodies↗
PubMed1985

Effects of four stereoisomers of beta-hydroxyglutamic acid on identifiable giant neurons of an African giant snail (Achatina fulica Férussac).

The effects of four stereoisomers of beta-hydroxyglutamic acid (erythro-L-BHGA, threo-L-BHGA, erythro-D-BHGA and threo-D-BHGA) and glutamic acid (L-Glu and D-Glu) were compared on six identifiable giant neurons of Achatina fulica Férussac, namely, PON (periodically oscillating neuron), VIN (visceral intermittently firing neuron), d-RPLN (dorsal-right parietal large neuron), RAPN (right anterior pallial neuron), FAN (frequently autoactive neuron) and v-RCDN (ventral-right cerebral distinct neuron). On PON and VIN, erythro-L-BHGA was the most inhibitory (effective potency quotient (EPQ) of the substance: 1.0). Its minimum effective concentration (MEC) for both neurons was the same at 3 X 10(-5) M. The effect of threo-L-BHGA was weaker (EPQ in relation to the most effective substance: 0.3-0.1). Erythro- and threo-D-BHGAs were almost ineffective on PON (EPQ: less than 0.03) though they had some effects on VIN (EPQ: 0.1-0.03 for erythro-D-BHGA and 0.3-0.1 for threo-D-BHGA). On d-RPLN, erythro-L-BHGA was the most excitatory (MEC: 10(-4)M). Threo-L-BHGA and threo-D-BHGA also had some effects (EPQ: 0.1 and 0.3 respectively), while erythro-D-BHGA was ineffective. On RAPN, erythro- and threo-L-BHGAs were the most excitatory (MEC: 10(-4) M). Threo-D-BHGA was also excitatory (EPQ: 0.3), while erythro-D-BHGA was ineffective. Threo-L-BHGA was the most inhibitory on FAN and v-RCDN (MEC: 10(-4) M in FAN and 10(-5) M in v-RCDN).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1984

Application of high-performance liquid chromatography with synchronized accumulating radioisotope detector to analysis of glyceryl trinitrate and its metabolites in rat plasma.

A new, sensitive, and specific high-performance liquid chromatographic method for the quantitative analysis of [14C]glyceryl trinitrate and its four metabolites in plasma is described. The drugs are extracted from 0.05 ml of plasma with methanol and analyzed by high-performance liquid chromatography using a synchronized accumulating radioisotope detector. The limit of detection is 0.2 ng per injection. The within-day coefficient of variation is 5.9% at a concentration of 27.0 ng per ml of plasma. The method was applied to single-dose pharmacokinetics of glyceryl trinitrate in rat.

Animals↗