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Biomedical subjects

N Katunuma

Publications and source records attributed to N Katunuma.

At least 217 records · Page 12Linked to original sources
PubMed1981

Immunological cross-reactivity of gamma-glutamyltranspeptidases from human and rat kidney, liver, and bile.

Antisera to purified gamma-glutamyltranspeptidase (gamma GTP) from human and rat kidney were prepared, and their reactivities toward purified gamma GTP from kidney, liver, and bile were tested. The following results were obtained: 1. On double immunodiffusion, Triton-solubilized gamma GTP, and papain-solubilized gamma GTP from rat kidney gave single precipitin lines which fused completely against antiserum to the purified enzyme from rat kidney. 2. An antigen-antibody complex of human kidney gamma GTP retained about 50% of the catalytic activity of the antigen. 3. Double immunodiffusion showed that the enzymes from human liver, kidney, and bile were immunologically identical. 4. Antiserum to rat kidney gamma GTP partially cross reacted with human gamma GTP, but antiserum to human gamma GTP reacted only very weakly with rat gamma GTP. It is concluded that gamma GTP of human liver, kidney, and bile are immunologically identical and that rat gamma GTP and human gamma GTP have certain antigenic determinants in common.

Animals↗
PubMed1981

Connectin, an elastic protein of muscle. Effects of proteolytic enzymes in situ.

The effects of various proteolytic enzymes on the high molecular weight protein (connectin) present in a direct sodium dodecyl sulfate extract of myofibrils from chicken breast muscle were studied in detail. To keep the high molecular weight proteins intact, myofibrils had to be prepared in the presence of EGTA. Trypsin, chymotrypsin, papain, and nagarse readily hydrolyzed connectin (doublet band of titin) and the band 3 protein (N2-line protein). Pepsin did not attack connectin, but digested the band 3 protein and myosin. Calcium-activated neutral proteinase hydrolyzed the band 3 protein, leaving connectin intact. On the other hand, serine protease digested connectin but not the band 3 protein.

Animals↗
PubMed1981

Susceptibilities of various myofibrillar proteins to cathepsin B and morphological alteration of isolated myofibrils by this enzyme.

The abilities of cathepsin B purified from liver to degrade purified myofibrillar proteins, myosin, actin, troponin, tropomyosin, and alpha-actinin from rabbit skeletal muscle were studied. The amino acids or peptides liberated from these proteins by cathepsin B were determined quantitatively by fluorometry with o-phthalaldehyde, and qualitatively by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. At a molar ratio of cathepsin B to substrate of 1 : 100, the order of susceptibilities was myosin much greater than troponin greater than tropomyosin much greater than actin. alpha-Actinin was not degraded. Myosin heavy chain was degraded to several fragments with molecular weights of 175,000, 170,000, 160,000, and 145,000, whereas the light chains were scarcely degraded. Cathepsin B degraded troponin-T rapidly, and troponin-I more slowly, but did not degrade troponin-C. Troponin-T and troponin-I were degraded to three fragments with molecular weights of 30,000, 18,000, and 12,800. Tropomyosin was degraded slightly and its product had a molecular weight of 32,000. Actin was also degraded only slowly, and no liberated product could be detected. Morphological changes in myofibrils prepared from glycerinated psoas muscle of rabbit during incubation with cathepsin B were observed. Three notable phenomena were observed: 1) disappearance of the Z-band in the early stage of incubation, 2) disappearance of the M-line following loss of the Z-band, and 3) decrease in the density of the A-band after swelling of the myofibrils.

Actins↗
PubMed1981

Effects of cathepsin B, H, and D in pectoral muscle of dystrophic chickens (line 413) of in vivo administration of E-64-c (N-[N-(L-3-transcarboxyoxirane-2-carbonyl)-L-leucyl]-3-methyl-butylamine).

The total activities of cathepsin B and cathepsin H in pectoral muscle of dystrophic chickens (Line 413) were about two times higher than in control chickens (Line 412), and cathepsin D activity was about 3 times higher in this muscle in the dystrophic chickens. When E-64-c, a synthesized potent thiol inhibitor was injected subcutaneously, in various doses, daily for 80 days into dystrophic chickens (L 413), the activities of cathepsin B and cathepsin H were reduced to the levels in control chickens (Line 412), but cathepsin D activity, which is insensitive to E-64-c in vitro, was not changed.

Animals↗
PubMed1981

Cell-free synthesis of ornithine aminotransferase of rat liver.

Mitochondrial ornithine aminotransferase was synthesized in a rabbit reticulocyte cell-free system using polysomal mRNA from rat liver. Upon analyzing the primary translation product by electrophoresis and fluorography, we found that ornithine aminotransferase is synthesized not as a large precursor but as one with its authentic size. Free ribosomes were found to be the main site of synthesis of ornithine aminotransferase.

Animals↗
PubMed1981

Rat liver thiol proteinases: cathepsin B, cathepsin H and cathepsin L.

Data on following points of lysosomal thiol proteinases (cathepsins B, H and L) from rat liver are described in this paper: Partial amino acid sequence of cathepsin B, substrate specificity of cathepsin L, immunological studies of cathepsin B and H and effectiveness of E-64, specific thiol proteinase inhibitor in vivo.

Amino Acid Sequence↗
PubMed1980

Characterization of human serum gamma-glutamyltranspeptidase.

The contribution of proteolysis to leakage of gamma-glutamyltranspeptidase from the liver into the serum was examined by comparing the properties of human serum gamma-glutamyltranspeptidase with those of partially purified enzyme preparations solubilized from human liver with Triton X-100 and with papain. The Triton-solubilized enzyme was hydrophobic, whereas the papain-solubilized enzyme was hydrophilic. Serum gamma-glutamyltranspeptidase was found to be hydrophilic, since it could be extracted without addition of detergent after acetone treatment to remove bound cholate. The affinity of serum-gamma-glutamyltranspeptidase to concanavalin A-Sepharose was compared with those of the Triton-solubilized and papain-solubilized enzymes. All three enzymes were adsorbed to concanavalin A-Sepharose in 50 mmol/l imidazole buffer, pH 7.2. The serum enzyme and papain-solubilized enzyme were eluted with 100 mmol/l alpha-methylmannoside in 50 mmol/l imidazole buffer containing 1% Triton X-100. The molecular weights of the Triton-solubilized, papain-solubilized and serum-gamma-glutamyltranspeptidases were estimated as 98 000 +/- 2000, 90 000 +/- 2000 and 90 000 +/- 2000, respectively, by electrophoresis. These results show chemical similarities between the serum-gamma-glutamyltranspeptidase and papain-solubilized gamma-glutamyltranspeptidase.

Adult↗
PubMed1980

Purification and characterization of yeast protease B.

Protease B [EC 3.4.22.9] was purified from baker's yeast by plasmolysis of yeast, acid activation, acid precipitation, and column chromatographies on QAE-Sephadex, SP-Sephadex, D-tryptophan methyl ester-Sepharose 4B and Sephadex G-100. The purified enzyme was inhibited by phenylmethylsulfonyl fluoride and sulfhydryl-blocking reagents. Chymostatin and antipain at extremely low concentrations (1 micro M) inhibited the protease B. The effects of the enzyme on various yeast enzymes were examined by measuring their inactivation. The enzyme inactivated 6-phosphogluconate dehydrogenase [EC 1.1.1.44] and uricase [EC 1.7.3.3], but not malate dehydrogenase [EC 1.1.1.37], alcohol dehydrogenase [EC 1.1.1.1], glutamate dehydrogenase [EC 1.4.1.3], glucose-6-phosphate dehydrogenase [EC 1.1.1.49] or hexokinase [EC 2.7.1.1].

Drug Stability↗
PubMed1980

Inhibitions by E-64 derivatives of rat liver cathepsin B and cathepsin L in vitro and in vivo.

The mechanism of inhibition of cathepsin B [EC 3.4.22.1] and cathepsin L [EC 3.4.22.-] by E-64 was investigated. Kinetic studies indicated that E-64 was an irreversible inhibitor of these enzymes. [3H]E-64 is incorporated into cathepsin B in a one/one molar ratio in parallel with inactivation of the enzyme. Titration of one of the 10 SH groups of native cathepsin B with 2,2'-dithiodipyridine resulted in complete loss of enzyme activity. Decrease of titratable SH groups and activity of cathepsin B was proportional to the concentration of E-64 added, indicating that E-64 binds to an equimolar amount of active SH residues of cathepsin B. The effects of E-64 and its derivatives on lysosomal cathepsin B and cathepsin L in rat liver were studied in vitro and in vivo. The D form of E-64 inhibited the cathepsin both in vitro and in vivo, although its inhibitory effects were less than those of E-64-(L). E-64-b(RR), in which the terminal agmatine of E-64 is replaced by leucine, was as active as E-64-(L) in vitro, but was completely inactive in vivo. Among the E-64 derivatives tested, E-64-c(SS), in which the terminal agmatine of E-64 is replaced by isoarylamide, showed strong inhibitory activity in vivo, like E-64-(L).

Agmatine↗
PubMed1980

Studies on the structure of gamma-glutamyltranspeptidase. I. Correlation between sialylation and isozymic forms.

Papain solubilized gamma-glutamyltranspeptidase was purified by DEAE-cellulose column chromatography. Four fractions were obtained as single proteins, each with a single isoelectric point, and fifth and sixth fractions were obtained as mixtures of several components. The molecular seights of the subunits of each form and their amino acid compositions and carboxyl-terminals were determined and found to be identical. The isoelectric points of the four purified enzymes and the main bands of the fifth fraction were pH 8.3, 8.0, 7.5, 6.7, and 6.0, respectively. The sixth fraction gave five bands with isoelectric points of pH 5.6, 5.3, 5.1, 4.6, and 4.4. An asialo-form of the enzyme, obtained by treatment with neuraminidase, had an isoelectric point of pH 8.6. A linear relationship was found between the isoelectric points of the enzymes and their contents of sialic acid, indicating that the heterogeneity of papain-solubilized gamma-glutamyltranspeptidase is mostly due to differences in the extends of sialylation of the enzymes. The distribution of the activity in rat kidney as follows: 29% in a poorly sialylated fraction (isoelectric point (Ip) 8.3 to 6.7), 24% in a moderately sialylated fraction (Ip 6.6 to 6.0), and 45% in a highly sialylated fraction (Ip 5.6 to 4.4).

Amino Acids↗
PubMed1980

Characteristics of proline oxidase in rat tissues.

In adult rats the activity of proline oxidase is high in the liver and kidney and moderate in the brain and heart, but it is not detectable in the lung, skeletal muscle, spleen, or small intestine. The activity in the liver is 1.5 times higher in females than males. Administration of estrogen to male rats increased the activity in liver and decreased that in kidney. Administration of a high protein diet increased the activity in the liver only. Administration of hydrocortisone or dexamethasone did not affect the activity in any tissue.

Animals↗