Search PubMed⌕ Search

Biomedical subjects

M Irie

Publications and source records attributed to M Irie.

At least 127 records · Page 7Linked to original sources
PubMed1993

Crystal structure of ribonuclease Ms (as a ribonuclease T1 homologue) complexed with a guanylyl-3',5'-cytidine analogue.

A ribonuclease T1 homologue, ribonuclease Ms (RNase Ms) from Aspergillus saitoi, has been crystallized as a complex with a substrate analogue GfpC where the 2'-hydroxyl (2'-OH) group of guanosine in guanylyl-3',5'-cytidine (GpC) is replaced by the 2'-fluorine (2'-F) atom to prevent transesterification. The crystal structure of the complex was solved at 1.8-A resolution to a final R-factor of 0.204. The role of His92 (RNase T1 numbering) as the general acid catalyst was confirmed. Of the two alternative candidates for a general base to abstract a proton from the 2'-OH group, His40 and Glu58 were found close to the 2'-F atom, making the decision between the two groups difficult. We then superposed the active site of the RNase Ms/GfpC complex with that of pancreatic ribonuclease S (RNase S) complexed with a substrate analogue UpcA, a phosphonate analogue of uridylyl-3',5'-adenosine (UpA), and found that His12 and His119 of RNase A almost exactly coincided with Glu58 and His92, respectively, of RNase Ms. Similar superposition with a prokaryotic microbial ribonuclease, RNase St [Nakamura, K. T., Iwahashi, K., Yamamoto, Y., Iitaka, Y., Yoshida, N., & Mitsui, Y. (1982) Nature 299, 564-566], also indicated Glu58 as a general base. Thus the present comparative geometrical studies consistently favor, albeit indirectly, the traditional as well as the most recent notion [Steyaert, J., Hallenga, K., Wyns, L., & Stanssens, P. (1990) Biochemistry 29, 9064-9072] that Glu58, rather than His40, must be the general base catalyst in the intact enzymes of the RNase T1 family.

Amino Acid Sequence↗
PubMed1993

Amino acid sequence of an intracellular, phosphate-starvation-induced ribonuclease from cultured tomato (Lycopersicon esculentum) cells.

The primary structure of an intracellular ribonuclease (RNase LX) from cultured tomato (Lycopersicon esculentum) cells has been determined. Previous studies have shown that the protein is located inside the tomato cells but outside the vacuoles and that its synthesis is induced after depleting the cells for phosphate [Löffler, A., Abel, S., Jost, W., Beintema, J. J., Glund, K. (1992) Plant Physiol. 98, 1472-1478]. Sequence analysis was carried out by analysis of peptides isolated after enzymatic and chemical cleavage of the protein. RNase LX consists of 213 amino acids and has a molecular mass of 24300 Da and an isoelectric point of 5.33. The enzyme contains 10 half-cystines and there are no potential N-glycosylation sites detectable in the sequence. RNase LX, as compared to an extracellular tomato RNase (RNase LE), which is also phosphate regulated and the amino acid sequence of which was recently established [Jost, W., Bak, H., Glund, K., Terpstra, P. & Beintema, J. J. (1991) Eur. J. Biochem. 198, 1-6] has 60% of all amino acids identical and in identical positions, revealing a high degree of similarity between both proteins. In contrast to RNase LE, RNase LX has a C-terminal extension of nine amino acids. The C-terminal tetrapeptide HDEF may be a retention signal of the protein in the endoplasmic reticulum.

Amino Acid Sequence↗
PubMed1993

Induction of metallothionein in a human astrocytoma cell line by interleukin-1 and heavy metals.

The effects of cytokines and heavy metals on the expression and localization of metallothioneins (MTs) within U373MG astrocytoma cells were analyzed by using indirect immunofluorescence using a monoclonal anti-MT antibody (MT45). IL-1, CdCl2 (50 microM) or ZnCl2 (500 microM) remarkably augmented intracellular MT levels, whereas IL-6 or 10 microM of ZnCl2 showed no inducing activity. From 24 to 48 h after the addition of CdCl2 or IL-1, immunoreactive MTs were found in the cytoplasm and the nucleus. After 72 h, immunoreactive MTs accumulated in a granular form near the cell surfaces in the presence of CdCl2 (50 microM) or IL-1 plus ZnCl2 (10 microM). However, this accumulation was not observed when only IL-1 was added. Thus, Zn2+ facilitated the appearance of the granular form of immunoreactive MTs at a concentration where they do not induce MTs by themselves.

Astrocytoma↗
PubMed1993

Rapid degradation of cucumber cotyledon lipoxygenase.

The lipoxygenase activity from cucumber cotyledons grown with their embryonic axis was separated into two fractions having M(r)s of 90,000 and 96,000, respectively, by hydrophobic chromatography. However, from de-embryonated cucumber cotyledons, only one form of lipoxygenase having a M(r) of 90,000 was purified. The three lipoxygenases could not be distinguished from each other either immunologically or by their enzymatic properties. Furthermore, peptide maps of the 90,000 and 96,000-lipoxygenases were identical. In a crude homogenate of cucumber cotyledons, the 96,000-lipoxygenase was rapidly degraded to the 90,000-form. Thus, it was inferred that the 90,000-lipoxygenase was probably the 96,000-form which had lost a peptide fragment of 6,000. It is suggested that there is a specific proteolytic activity for the degradation of 96,000-lipoxygenase. Estimation of changes in the proteolytic activity during seedling growth suggests that the activity at least partly contributes to the rapid in vivo degradation of cucumber cotyledon lipoxygenase.

Amino Acid Sequence↗
PubMed1993

Isolation and characterization of a major allergenic component (gp55) of Aspergillus fumigatus.

IgE class antibodies specific for antigens in a water-soluble extract of Aspergillus fumigatus (strain NHL-5759) were analyzed by immunoblotting with sera from patients with allergic bronchopulmonary aspergillosis. All the sera tested were reactive with a major 50 to 60 kd protein in the extract. This allergen, designated gp55, was purified by gel filtration and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The antigen was found to be present in the water-soluble extract in the form of a complex composed of approximately eight molecules of gp55. The carbohydrate and phosphate content of the purified antigen were 23.1% and 0.46%, respectively. The molar ratio of mannose to galactose residues was 2.76:1, and the protein was glycosylated predominantly with N-linked oligosaccharides. The serologic activity of the gp55 antigen was abolished by treatment with nonspecific protease (Pronase) but not by treatment with sodium metaperiodate or endoglycosidases. Thus the major antigenic site of the glycoprotein is located within its peptide moiety. The antigen itself displayed no chymotryptic or tryptic activity. The amino acid sequence of the 20 N-terminal residues of the antigen (ATPHEPVFFSWDAGAVTSFP) is different from that of any other protein previously reported.

Amino Acid Sequence↗
PubMed1993

Role of Asp51 and Glu105 in the enzymatic activity of a ribonuclease from Rhizopus niveus.

The active site of a base non-specific RNase from Rhizopus niveus (RNase Rh), consists of three histidine residues and one carboxyl group [Ohgi, K. et al. (1992) J. Biochem. 111, 132-138]. In order to identify this acidic amino acid residue, we chose Asp51 and Glu105 as candidates based on a comparison of the primary structures of four fungal RNases and self-incompatibility factors of Nicotiana alata which belong to the RNase T2 family. We substituted these amino acid residues with other amino acids by site-directed mutagenesis, and determined the enzymatic properties of the mutated enzymes. The enzymatic activities of E105Q, E105D, and E105A mutant enzymes were decreased markedly, but those of D51N, D51E, and D51A were decreased only slightly when RNA was used as a substrate. Therefore we concluded that Glu105 is related to the catalytic function. Kinetic constants for the enzymatic activity of E105Q and E105D toward ApU suggest that the proper size and negative charge of side chain groups are important for the catalysis of RNase Rh. However, the enzymatic activity of D51N toward ApU, but not toward UpU, decreased markedly. Therefore, we suggest that Asp51 is one of the amino acid residues forming the base recognition site. The substitution of Asp51 by Asn causes the enzyme to be more guanine nucleotide-preferential.

Amino Acid Sequence↗
PubMed1993

Purification, some properties, and primary structure of base non-specific ribonucleases from Physarum polycephalum.

Two ribonucleases (RNase Phya and RNase Phyb) were purified to homogeneity on SDS-PAGE from the culture filtrate of the fungus Physarum polycephalum. The apparent molecular weights of RNases Phya and Phyb were about 20,000. The pH optima of these two RNases were around 4.5-4.75. The RNases released mononucleotides from RNA in the order of 3'-GMP, 3'-AMP, and 3'-pyrimidine nucleotides. RNase Phya and RNase Phyb have the N-terminal amino acid sequences STSFD--- and KSTSF--, respectively. This finding and the similar amino acid compositions of both RNases indicated that they might share the same protein moiety except for the N-terminus Lys. The complete primary structure of RNase Phyb was determined, mostly by analysis of the peptides generated by trypsin, V8 protease, and lysylendopeptidase digestions. The molecular weight of the protein moiety was 19,704. The locations of four half cystine residues were almost superimposable on those in five known fungal RNase T2 family RNases, but two others were not. The sequence homology between RNase Phyb and five known fungal RNases amounted to 53-59 residues, which are concentrated around the three histidine residues, supposed to form the active site in enzymes of the RNase T2 family. However, the amino acid sequence of RNase Phyb more closely resembles those of plant RNases such as RNases from Nicotiana alata [McClure, B.A. et al. (1989) Nature 342, 955-957], tomato [RNase Le, Yost et al. (1991) Eur. J. Biochem. 198, 1-6], and Momoridica charantia [RNase MC1, Ide et al. (1991) FEBS Lett. 284, 161-164].

Amino Acid Sequence↗
PubMed1993

Characterization of poly C preferential ribonuclease from chicken liver.

Poly C preferential RNase previously reported by Levy and Karpetsky [J. Biol. Chem. 255, 2153-2159 (1980)] and Miura et al. [Chem. Pharm. Bull. 32, 4053-4060 (1984)] was extensively purified from chicken liver to homogeneity as determined by SDS-PAGE (RNase CL2). The poly C preference over poly U was slightly higher than that of bovine pancreatic RNase A. However, the kinetic constants for 8 dinucleoside phosphates, CpY and UpY (Y = one of A, G, U, and C) as substrates showed that RNase CL2 was preferential for cytidylic acid, but less so than RNase A, and the influence of Y base on the rate of hydrolysis of CpY or UpY was less marked than in the case of RNase A. The primary structure of RNase CL2 was determined. The molecular weight calculated from the sequence was 13,420. Comparison of the amino acid sequence of RNase CL2 with those of other vertebrate RNases showed that RNase CL2 is a member of the RNase A family, but is not a non-secretory RNase. It retains 3 disulfide bridges of RNase A, but Cys65-Cys72 of RNase A is missing. As for the active site, the amino acid residues of the P0 and P1 sites of RNase A are completely conserved. Among the B1 site components, Thr45 (RNase A numbering) is conserved, but Phe120 and Ser123 are substituted by Leu and Thr, respectively. Among the B2 site residues, Gln69, Asn71, and Glu111 are substituted by other amino acids.

Amino Acid Sequence↗
PubMed1993

Purification, some properties, and primary structure of a base non-specific ribonuclease from oyster (Crussdstrea grigus).

A ribonuclease (RNase Oy) was purified to homogeneity on SDS-PAGE from the homogenate of oyster (Crussdstrea grigus). The apparent molecular weight estimated from SDS-PAGE was ca. 28 kDa. The pH optimum of the RNase was 5.0. The RNase released mononucleotides from RNA in the order of 3'-GMP, 3'-AMP, and 3'-UMP. The complete amino acid sequence of RNase Oy was determined, mostly by analyzing the peptides generated by BrCN cleavage or digestion by lysylendopeptidase, staphylococcal V8 protease, and alpha-chymotrypsin. The molecular weight of the protein moiety of RNase Oy deduced from the sequence was 24,359. The sequence of RNase Oy contained two typical histidine residues in segments common to the active site of RNase T2 family enzymes. The locations of six half cystine residues among eight were almost superimposable on those of four known plant RNases of RNase T2 family. The sequence homology between RNase Oy and five fungal and four plant RNases amount, to 43-56 amino acid residues. The amino acid sequence of the N-terminal part of RNase Oy is more similar to those of plant RNases than to those of fungal RNases. This RNase is the first RNase T2 family RNase from mollusc whose primary structure has been elucidated.

Amino Acid Sequence↗
PubMed1993

Maturational changes of urinary growth hormone excretion in the premature infant.

High plasma GH concentrations are observed in the newborn infant. To characterize the maturational change of GH secretion in premature infants, we serially measured 24-h urinary GH excretion in 30 premature infants. The gestational age ranged from 25-37 weeks and birth weight from 468-2415 g. Urinary GH excretion at 1 week of age was negatively correlated with gestational age, birth weight, and length of infants with adequate intrauterine growth. In the infants with 27 weeks of mean gestation (range, 25-28 weeks) mean urinary GH excretion was highest (6.1 micrograms/day) at the first week, decreased to 1.2 micrograms/day by the fourth week, and remained between 0.05 and 0.18 micrograms/day thereafter. When compared to the corresponding conceptional age, there was no postnatal difference in the pattern of GH excretion between infants with 27 and 31 (range, 29-32) weeks of mean gestational age. Persistent hyperexcretion of GH was observed in 4 of the 5 infants with intrauterine or postnatal growth retardation. Our results suggest that the postnatal change of 24-h urinary GH excretion is similar to ontogenic changes of plasma GH in fetus, and GH may have some effects on postnatal growth in premature infants.

Aging↗
PubMed1993

The detection of a mutation of CD18 gene in bovine leukocyte adhesion deficiency (BLAD).

Two calves (5 and 9 months old) affected with pneumonia and gingivitis were also diagnosed as having bovine leukocyte adhesion deficiency (BLAD). The gene of leukocyte adhesion molecule CD18 in these BLAD calves and their dams (carrier) were examined by means of polymerase chain reaction (PCR) and digestion of restriction endonuclease. The splicing in mRNA coded CD18 reported in human LAD was not recognized in BLAD on the basis of the results of PCR amplification. The region including the portion of point mutation, which corresponded to the region reported in the human patient, was amplified by PCR, and the PCR product was then digested with Taql. An obvious difference was recognized in the pattern of digestion among healthy calves, BLAD calves and their dams. In BLAD, therefore, the point mutation reported in human patients was strongly suggested. Moreover it may be a method able to be used in detecting the carrier.

Animals↗
PubMed1993

[A case of hereditary motor and sensory neuropathy (HMSN type 2) with bilateral recurrent nerve palsy].

An atypical case of hereditary motor and sensory neuropathy (HMSN) type 2 with cerebellar ataxia, hand tremor and bilateral recurrent nerve palsy was described. The patient was a 57-year-old man who complained of dyspnea, stridor , hoarseness during exercise and snored heavily during sleep since he was 20 years old. These symptoms and signs were slowly progressive. He had difficulty in breathing even at resting state when he was 54 years old and since then, he noticed muscle wasting of his hands and feet. Neurological examinations on admission revealed pes cavus, scoliosis, distal muscular atrophy in his four extremities, especially severe in bilateral lower limbs. Deep tendon reflexes were diffusely depressed. The fiberscopic examination demonstrated the limitation of bilateral vocal cord abduction and his tongue was slightly atrophic. Fine postural tremor was found in bilateral hands. Mild limb and truncal ataxias were also noted. Blood pCO2 level was elevated to 66% although FEV1.0% and vital capacity were within normal limits. Peripheral nerve conduction velocities were almost normal, though distal terminal latencies were slightly prolonged and amplitudes of evoked potentials were markedly decreased. The sural nerve biopsy studies revealed the chronic axonal or neuronal degeneration of both large and small myelinated fibers. From the clinical, electrophysiologic and histopathologic findings, the diagnosis of HMSN type 2 with bilateral recurrent nerve palsy and other atypical neurological findings was made. It is practically important to evaluate the presence or absence of vocal cord paralysis in the patients with HMSN from clinical viewpoints.

Biopsy↗
PubMed1992

Crystal and molecular structure of RNase Rh, a new class of microbial ribonuclease from Rhizopus niveus.

The crystal structure of RNase Rh, a new class of microbial ribonuclease from Rhizopus niveus, has been determined at 2.5 A resolution by the multiple isomorphous replacement method. The crystal structure was refined by simulated annealing with molecular dynamics. The current crystallographic R-factor is 0.200 in the 10-2.5 A resolution range. The molecular structure which is completely different from the known structures of RNase A and RNase T1 consists of six alpha-helices and seven beta-strands, belonging to the alpha+beta type structure. Two histidine and one glutamic acid residues which were predicted as the most probably functional residues by chemical modification studies are found to be clustered. The steric nature of the active site taken together with the relevant site-directed mutagenesis experiments (Irie et al.) indicates that: (i) the two histidine residues are the general acid and base; and (ii) an aspartic acid residue plays a role of recognizing adenine moiety of the substrate.

Amino Acid Sequence↗
PubMed1992

[Long-term treatment of acromegaly and gigantism with octreotide (SMS 201-995)].

Twenty-one patients with active acromegaly and two patients with pituitary gigantism were treated with the long-acting somatostatin analogue octreotide (100-600 micrograms/day, sc, two or three times daily or 300-1500 micrograms daily by intermittent sc infusion) for 9-63 months. There was rapid clinical improvement. The fasting plasma GH levels were significantly suppressed (less than 50% of the values before treatment) in 17 patients and were normalized (less than 5 ng/ml) in 6 patients (27.3%). Plasma IGF-I levels were lowered by 50% and were normalized in 7 out of 18 cases. The effect of octreotide on pituitary tumor size was evaluated in 13 patients. In 4 cases, the shrinkage of the pituitary tumor was detected by computed tomographic scans and/or magnetic resonance imaging studies. The drug was generally well tolerated. However, there were probably newly formed gallstones in two patients during the therapy. Our study suggests that octreotide is an effective and relatively safe new approach for treating active acromegaly and gigantism.

Acromegaly↗
PubMed1992

Histochemical and fine structural study of bone of ipriflavone-treated rats.

Bone labeling, histochemical, and fine structural studies were performed in order to clarify the effects of ipriflavone (IP) on rat bone tissue in vivo and in vitro. Labeling experiments showed a slight increase in bone formation during 3 days' administration. It was also noted that many osteoclasts detached from the bone surface at 1, 2, and 6 hours after administration in vivo. In addition, irregular localization of tartrate-resistant acid phosphatase (TRACPase) activity was observed in osteoclasts. Fine structurally, IP-treated osteoclasts exhibited irregularity in their ruffled borders, as reported in calcitonin administration, and many enlarged rough endoplasmic reticuli and vacuoles were observed. However, osteoclasts at 12 hours after administration, as well as the control, indicated recovery features from the effect of IP. Osteoblast proliferation and differentiation led to increasing alkaline phosphatase activity (ALPase) with time as well as the development of rough endoplasmic reticuli and Golgi apparatus with well-developed fine structure. These findings imply active synthesis of bone matrix. In our in vitro experiment, osteoclasts and osteoblasts displayed histochemical and fine structural characteristics similar to those observed in our in vivo experiment. Moreover, fewer TRACP-positive mononuclear cells were observed after 24-hour culture with IP than with the control. These results suggest that IP inhibits directly and/or indirectly differentiation and activity of osteoclasts and also promotes differentiation of osteoblast-lineage cells and their bone-forming activity.

Acid Phosphatase↗
PubMed1992

Identification of metallothionein in cultured cells by immunoblotting and immunofluorescence using a new monoclonal antibody.

A hybridoma clone (MT45-5-3) producing an IgG-class monoclonal antibody specific for metallothioneins (MTs) was established. The monoclonal antibody (MT45) cross-reacted with mouse, rat and rabbit Cd(2+)-induced MTs 1 and 2 and Zn(2+)-induced MT 2 as assessed by enzyme-linked immunosorbent assay. When the antibody was used to detect the MTs transferred to nylon membranes after SDS-polyacrylamide gel electrophoresis, the antibody reacted with cultured human cell MTs as well as rat, mouse and rabbit MTs 1 and 2 even after carboxymethylation. The antibody could be used for the indirect immunofluorescence test for Cd(2+)-induced MTs in cultured human and mouse cells.

Animals↗