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Biomedical subjects

H Matsubara

Publications and source records attributed to H Matsubara.

At least 379 records · Page 21Linked to original sources
PubMed1984

Rebound phenomenon in glycerol test.

The glycerol effect for endolymphatic hydrops is well known for an improvement in pure tone threshold three hours after glycerol administration. However, long-term effects of glycerol, i.e., longer than three hours after administration, are unknown. In this study, audiometric tests were administered during 10 hours following glycerol administration in order to determine the long-term effects of glycerol in cases of Meniere's disease, sudden deafness, and normal subjects. The following results were obtained; 1) The long-term effects of glycerol in the pure tone threshold were observed only in cases of Meniere's disease and were classified into the following four types: "descending type", "descending and ascending type", "ascending type" and "unchanged type". 2) The long-term effects, including rebound phenomenon, on hearing ability did not appear in cases of sudden deafness and normal subjects. 3) About 50% of patients with Meniere's disease showed rebound phenomenon on hearing ability and it was considered to be specific for Meniere's disease.

Audiometry↗
PubMed1983

Complete amino acid sequence of an alpha-amylase inhibitor in wheat kernel.

We recently purified a new alpha-amylase inhibitor (called 0.53-inhibitor according to its mobility on polyacrylamide gel electrophoresis, at pH 8.5, relative to Bromophenol blue (taken as 1), under the conditions described by O'Donnell, M.D. and McGeeney, K.F. (1976) Biochim. Biophys. Acta 422, 159-169)) from wheat kernel, which has 500-times greater inhibitory activity towards human salivary amylase than towards human pancreatic amylase (Maeda, K., Takemori, Y. and Oka, O. (1982) Agric. Biol. Chem. 41, 2873-2875). Elucidation of the primary structure and structural comparison with other amylase inhibitors are essential to understand the mechanism of the selective inhibitory behavior of 0.53-inhibitor. The complete amino acid sequence of 0.53-inhibitor has been determined after cleaving the protein with CNBr and trypsin separately. 0.53-Inhibitor is composed of two identical subunits with 124 amino acid residues and contains nine cysteine residues in each subunit. Comparison of the sequence of 0.53- and 0.28-inhibitor, which is a major alpha-amylase inhibitor in wheat, with Mr 12 000, of monomeric form, shows high sequence homologies of nine cysteine regions, but significant differences are evident.

Amino Acid Sequence↗
PubMed1983

Amino acid sequence studies of the light subunit of methylamine dehydrogenase from Pseudomonas AM1: existence of two residues binding the prosthetic group.

The methylamine dehydrogenase from Pseudomonas AM1 is a tetramer composed of two subunits, light(L)- and heavy-subunits. The amino acid sequence of the L-subunit was determined by sequence analyses of trypsin, chymotrypsin, staphylococcal protease, and thermolysin peptides of Cm-protein. The subunit consisted of a single polypeptide chain of 129 amino acid residues, with alanine and serine at the amino(N)- and carboxyl(C)-terminus, respectively. Yellow-colored peptides containing a prosthetic group were composed of two polypeptide chains and the prosthetic group was covalently bound to two residues at positions 55 and 106, which could not be identified yet. The molecular weight of the subunit was 13,500 excluding the binding residues and the prosthetic group. Various structural features are discussed.

Amino Acid Sequence↗
PubMed1983

Structure of the extracellular ferredoxin from Rhodospirillum rubrum: close similarity to clostridial ferredoxins.

The amino acid sequence of an [8Fe-8S] ferredoxin isolated from the culture medium of Rhodospirillum rubrum, a photosynthetic purple non-sulfur bacterium, was determined by a combination of various conventional procedures. The sequence was A-Y-K-I-E-E-T-C-I-S-C-G-A-C-A-A-E-C-P-V-N-A-I-E-Q-G-D-T-I-F-V-V-N-A-D-T-C-I-D-C - G-N-C-A-N-V-C-P-V-G-A-P-V-A-E (55 amino acid residues). It lacked methionine, leucine, histidine, arginine, and tryptophan. The molecular weight was calculated to be 5,568 excluding iron and sulfur atoms. The distribution of 8 cysteine residues was exactly the same as that of clostridial-type ferredoxin, suggesting retention of the duplication of the bacterial ancestral ferredoxin gene. The extracellular ferredoxin of R. rubrum was compared with other ferredoxins observed in closely related photosynthetic bacteria and the evolutionary significance of this ferredoxin is discussed.

Amino Acid Sequence↗
PubMed1983

Partial amino terminal sequence of the precursor of mitochondrial ATPase inhibitor protein synthesized with mRNA partially purified by gel permeation chromatography.

Messenger RNA coding mitochondrial ATPase inhibitor protein, a small peptide comprised of 63 amino acid residues, was separated from a large quantity of mRNAs of larger molecules by high speed gel permeation chromatography. Messenger RNA coding a small stabilizing factor of inactivated F1F0-ATPase complex, which is also comprised of 63 amino acids, was recovered in the same fraction as the ATPase inhibitor, whereas mRNA for a large stabilizing factor with an apparent molecular weight of 15,000 was recovered in a fraction of slightly larger molecules. ATPase inhibitor precursor labeled with various kinds of radioactive amino acids was prepared separately by cell-free translation with the purified mRNA, and the amino terminal sequence of the precursor was examined. It was demonstrated that an extra peptide of 21 amino acid residues, including 5 leucine, 4 serine, 1 glycine, and 1 methionine residues, is located at the amino terminus of the ATPase inhibitor precursor.

Amino Acid Sequence↗
PubMed1983

Main chain fold of a [2Fe-2S]ferredoxin I from Aphanothece sacrum at 2.5 A resolution.

Crystal structure analysis of a [2Fe-2S]ferredoxin I from Aphanothece sacrum, a blue green alga, was carried out at 2.5 A resolution. The phase angle of each reflection was determined by the single isomorphous replacement method coupled with the anomalous dispersion effect for the uranium derivative. The four molecules in an asymmetric unit were clearly seen in a 3.9 A electron density map. The main chains of three molecules were traced at 2.5 A resolution. The structure of the remaining one molecule, however, remains unknown because of the poor electron density of the corresponding region. The three main chain folds exhibit the same topology as that in Spirulina platensis. The structural similarity between A. sacrum and S. platensis ferredoxins, whose amino acid sequences are different from each other by about 30%, strongly suggests that all plant-type ferredoxins have the same main chain fold.

Amino Acid Sequence↗
PubMed1983

A stabilizing factor of yeast mitochondrial F1F0-ATPase-inhibitor complex: common amino acid sequence with yeast ATPase inhibitor and E. coli epsilon and bovine delta subunits.

The amino acid sequence of a stabilizing factor, 9,000 dalton protein, of proton-translocating ATPase (F1F0-ATPase)-inhibitor complex isolated from yeast mitochondria was established. It was highly homologous with that of yeast intrinsic ATPase inhibitor and several structural characteristics were noted. They were compared with those of E. coli epsilon and bovine delta subunits to point out the similarity among them.

Adenosine Triphosphatases↗
PubMed1983

Spirulina ferredoxin-NADP+ reductase. Further characterization with an improved preparation.

The preparation procedure for Spirulina ferredoxin-NADP+ reductase (ferredoxin: NADP+ oxidoreductase, EC 1.18.1.2, FNR) was improved by adding protease inhibitors, phenylmethylsulfonylfluoride (PMSF) and EDTA, through the whole process of preparation and by introducing an affinity chromatography step on Blue Sepharose CL-6B. The addition of the inhibitors largely prevented the formation of the minor component (FNR I), and the affinity gel chromatography simplified the preparation process, shortening the exposure period of FNR to proteolysis. However, complete removal of the heterogeneity of FNR found at the amino (N)-terminal region was not achieved even by applying the new method. The affinity chromatography on the Blue Sepharose gel was also effective in purifying spinach FNR. The affinity of this gel for Spirulina FNR was compared with that for the enzyme derived from spinach leaves. The spinach enzyme had a higher affinity than the Spirulina one. Both enzymes showed the highest affinities to Blue Sepharose at 20--30 mM NaCl concentration. The N-terminal sequence analysis revealed that there was 4 forms, which were probably modifications produced by exopeptidase action during the preparation, or even in the living cells. The longest component gave the N-terminal sequence Ala-Lys-Thr-Asp-Ile-Pro-Val-Asn-Ile-Tyr-. The others lacked amino acids successively one by one from the N-terminus. In contrast, the carboxyl(C)-terminal residues of all 4 FNR forms were tyrosine. The probable C-terminal sequence was predicted to be -Trp-His-Val-Gln-Thr-Tyr based on a study of a cyanogen bromide peptide.

Amino Acid Sequence↗
PubMed1983

Disulfide bridges in an alpha-amylase inhibitor from wheat kernel.

An alpha-amylase inhibitor (0.53-inhibitor) was digested with pepsin and the cystine-containing peptides were isolated by SP-Sephadex C-25 column chromatography and high voltage paper electrophoresis. Amino acid compositions and partial sequences of these peptides and amino acid compositions of the peptides separated after performic acid oxidation revealed the presence of 4 disulfide bonds in the inhibitor. They were formed between residues 6 and 115, 20 and either 41 or 42, 99 and either 41 or 42, and 28 and 83. The disulfide bond partners of residues 20 and 99 were not conclusively determined because of the difficulty of cleavage of the Cys-Cys bond at residues 41 and 42. Among 9 cysteines in this inhibitor Cys-54 must be in a free form, since no evidence was obtained for its contribution to disulfide bond formation.

Amino Acid Sequence↗
PubMed1983

Classification of iron-sulfur cores in ferredoxins by 1H nuclear magnetic resonance spectroscopy.

A 1H nuclear magnetic resonance (NMR) study was carried out on various ferredoxins which possess one of three types of iron-sulfur clusters, (2Fe-2S), (3Fe-3S), or (4Fe-4S). In the isolated form, (2Fe-2S) ferredoxins from spinach (Spinacea oleracia), pokeweed (Phytolacca americana), a blue-green alga (Spirulina platensis), and a halobacterium (Halobacterium halobium) exhibited two broad resonances common in chemical shift at the region downfield of 10 ppm. In their reduced forms, seven contact-shifted resonances appeared spread over 30 ppm. Although the positions of the contact-shifted resonances in the reduced state differed among the four, a common trend in the temperature dependence of their resonance positions was recognized. Two (4Fe-4S) ferredoxins from Bacillus stearothermophilus and Bacillus thermoproteolyticus exhibited almost indistinguishable spectral patterns in both the oxidized and reduced forms. The ferricyanide-treated ferredoxins of B. stearothermophilus and B. thermoproteolyticus showed characteristic contact-shifted resonances distinct from the spectra of the original (4Fe-4S) ferredoxins. This corresponds to the recent finding of the interconversion of (4Fe-4S) and (3Fe-3S) clusters with ferricyanide in the ferredoxin. Based on our data together with reported NMR data on other ferredoxins, contact-shift resonances of three types of clusters were tabulated. The reliability of NMR classification increases when we compare the NMR spectra of a ferredoxin with the classification standards at the two redox states. Moreover, not only the absolute values of the chemical shifts of contact-shifted resonances but also their temperature dependence give distinctive information applicable to iron core identification.

Azotobacter↗
PubMed1983

Ribosome-binding activities and antimicrobial activities of tylosin and its related compounds.

Structure-activity relationships of tylosin and related compounds were evaluated in terms of their antimicrobial and ribosome-binding activities. Demycarosyl derivatives, demycarosyltylosin and 20-deoxydemycarosylrelomycin, were slightly weaker than tylosin and 20-deoxyrelomycin, respectively, both in antimicrobial activity and in affinity to ribosomes. The corresponding demycarosyl-demycinosyl derivatives had weaker antimicrobial activities despite their relatively high affinities to ribosomes. A 23-deoxy-demycarosyl-demycinosyl derivative, 20-oxo-5-O-mycaminosylprotylonolide, had a higher affinity to ribosomes than that of tylosin and was equivalent to tylosin in antimicrobial activity against Gram-positive bacteria. These results suggest that the mycinose moiety increases the ability of the molecule to enter bacterial cells. Among the derivatives tested, a 23-iodo derivative, 20-deoxy-23-iodo-5-O-mycarosyltylonolide, had the highest affinity for ribosomes as well as the highest antimicrobial activity.

Anti-Bacterial Agents↗