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Biomedical subjects

K Shimura

Publications and source records attributed to K Shimura.

At least 145 records · Page 8Linked to original sources
PubMed1983

IMP dehydrogenase. II. Purification and properties of the enzyme from Yoshida sarcoma ascites tumor cells.

The preceding paper showed that IMP dehydrogenase [IMP:NAD+ oxidoreductase, EC 1.2.1.14] tended to form a precipitable complex(es) through ionic and hydrophobic interactions. On the basis of these observations, a method was developed for purification of IMP dehydrogenase from Yoshida sarcoma ascites cells. On SDS-polyacrylamide gel electrophoresis, the purified preparation (1.19 U/mg protein) appeared homogeneous and its minimum molecular weight was estimated to be 68K daltons. Amino acid analyses indicated a subunit molecular weight of 68,042. Molecular sieve chromatography in the presence of 10% (NH4)2SO4 showed that the molecular weight of the native enzyme was 127K daltons. These values indicate that the native enzyme is composed of two identical subunits. However, the purified enzyme gave 4 protein bands on polyacrylamide gel electrophoresis under non-denaturing conditions, and appeared as a single fraction in the vicinity of the void volume on Ultrogel AcA 34 column chromatography at low salt concentration, indicating that its molecular weight exceeded 200K daltons. These findings indicate that the enzyme tends to aggregate owing to its own physicochemical characteristics. The Km values for IMP and NAD were calculated to be 12 and 25 microM, respectively, and the Ki values for XMP, GMP, and AMP to be 109, 130, and 854 microM, respectively. The purified enzyme showed full activity in the presence of K+, and K+ could be partially replaced by Na+. PCMB inactivated the enzyme, but the activity was completely restored by the addition of DTT. Cl-IMP also inactivated the enzyme and IMP prevented this inactivation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

Affinophoresis of trypsins.

We devised a new separation technique for the protein, "affinophoresis," which is based on its specific affinity and utilizes electrophoresis. This technique requires a carrier macromolecule, "affinophore," which contains both an affinity ligand for a certain protein and many charges, either positive or negative, in order to migrate rapidly in an electric field. When a mixture of proteins is electrophoresed in the presence of the affinophore, the protein having an affinity with the ligand will form a complex with the affinophore. This results in a change in the apparent electrophoretic mobility. If the protein is sufficiently accelerated, we can separate it from other materials. A cationic affinophore for trypsin was prepared. Soluble dextran MW approximately 10,000) was coupled with a DEAE-group and m-aminobenzamidine, a competitive inhibitor of trypsins. Electrophoresis of trypsins from several origins on agarose gel plates in the presence of the affinophore showed that affinophoresis actually occurred. The electrophoretic mobilities of trypsins increased towards the cathode, the same direction as the affinophore movement. The presence of leupeptin and treatment of the trypsins with TLCK suppressed the effect of the affinophore. Streptomyces griseus trypsin, contained in Pronase, was easily separated and detected. This procedure is distinct from affinity chromatography and so-called affinity electrophoresis in that the support of the affinity ligand moves, and has advantages especially for analytical purposes: for example, the detection of specific molecules regardless of their isoelectric points.

Affinity Labels↗
PubMed1981

Initiation of fibroin biosynthesis. I. Isolation of nascent fibroin peptides from the posterior silk gland of Bombyx mori.

1. Peptidyl-tRNA was prepared from the posterior silk gland ribosomes of Bombyx mori on the fourth to fifth days of the fifth instar to explore the initiation process in fibroin biosynthesis. 2. The peptidyl-tRNA was hydrolyzed at an alkaline pH and the resulting nascent peptides were fractionated on Sephadex G-75 and Sephadex G-200 columns into twelve fractions. Each fraction was analyzed for amino acid composition. 3. The nascent peptides of smaller molecular size were rather rich in glutamic and aspartic acids. However, the amino acid composition of the nascent peptides gradually approached that of fibroin as their molecular size increased. 4. A comparison between the nascent peptides of smaller molecular size and the small subunit of fibroin was made in respect to amino acid composition and tryptic peptide map. Considerable similarity between these two proteins was observed. The implications of these results in relation to the initiation process in fibroin biosynthesis are discussed.

Amino Acid Sequence↗
PubMed1981

Analgesic effect of fentiazac after tooth extraction or minor oral surgery.

A new nonsteroidal anti-inflammatory agent, fentiazac, was used for analgesia after tooth extractions and minor oral surgery in two Japanese dental hospitals. The drug was administered as a single oral dose of either 50 mg or 100 mg. The 50-mg dose provided rapid analgesic effect, but its effect lasted only two to three hours in a number of patients. At a dose of 100 mg, fentiazac proved effective for 85% of 53 patients, usually providing marked reduction of disappearance of pain within one hour or less. Among patients in whom pain reappeared, the mean time for recurrence was four hours, indicating a satisfactory duration of analgesic effect. One side effect--loss of appetite--was reported by one patient in the entire series of 71 subjects. It is concluded that fentiazac is a highly effective analgesic agent with a wide margin of safety for use after dental procedures that produce pain.

Acetates↗
PubMed1980

Purification and properties of adenylosuccinate synthetase from Yoshida sarcoma ascites tumor cells.

Adenylosuccinate synthetase (IMP:L-aspartate ligase (GDP-forming), EC 6.3.4.4) was purified about 750-fold to a homogeneous state from Yoshida sarcoma ascites tumor cells. A yield of 38% purified enzyme was achieved by a procedure including affinity chromatography on hadacidin-Sepharose 4B. Ultracentrifugal analyses showed that the molecular weight of the native enzyme was 102 000 with an s20,w value of 4.5 and that the molecular weight in 6 M guanidine-HCl was 47 000. These values indicate that the native enzyme is composed of two subunits. The isoelectric point was determined to be 5.9 by isoelectric focusing. The optimum pH for activity was 6.8-7.0. The Km values for IMP, aspartate and GTP were calculated to be 4.1, 9.8 and 0.7 . 10(-4) M, respectively. The antibiotic, hadacidin was strongly inhibitory, causing competitive inhibition with respect to aspartate with a Ki value of 2.5 . 10(-6) M. Nucleoside mono- and diphosphate also inhibited the enzyme activity, but their inhibitions were not apparently specific. The purified enzyme showed full activity in the presence of Mg2+, and Mg2+ could be partially replaced by Mn2+, Co2+, Ca2+ or Cu2+. Divalent metal ions, such as Cd2+, Pb2+, Zn2+, Cu2+ and Mn2+, interfered with the activity by antagonizing Mg2+. Hg2+ or PCMB inactivated the enzyme, suggesting that an SH-group may be important for activity.

Adenylosuccinate Synthase↗
PubMed1980

Sequential grouping of nonhistone chromosomal protein from pig thymus.

1. To establish a practical method to prepare nonhistone chromosomal proteins (NHP's) in substantial quantity, a sequential group fractionation procedure for NHP's from pig thymus chromatin has been developed by a combination of methods based on the intrinsic properties, such as binding force in chromatin, molecular weight, and acidity and/or basicity of the protein components. 2. The loosely bound NHP's in chromatin have been grouped into 11 subfractions, and tightly bound ones into 6 subfractions, 2 of which were histones. The loosely bound NHP's were chiefly acidic to neutral in contrast with the tightly bound components, which were basic. In addition, the NHP's of high molecular weight were in general acidic to neutral, while the lower molecular weight components were mainly basic. 3. The present method is applicable to the preparation of representative fractions of NHP on the scale of 50--400 mg from 1 kg of pig thymus.

Amino Acids↗
PubMed1979

Technetium 99m bone imaging in the evaluation of cancer of the maxillofacial region.

Technetium 99m bone images were obtained from five patients with mandibular gingival carcinoma and six patients with maxillary sinus carcinoma. Ten to 15 mCi of 99mTc-polyphosphate was administered intravenously, and imaging was performed three hours after injection. The anterior and lateral views of the maxillofacial skeleton were obtained with a gamma camera. Resultant gamma camera images were compared with the radiographic skeletal survey. 99mTc bone survey is a safe and simple diagnostic technique that can demonstrate abnormality of the bone with greater sensitivity than routine radiographs.

Adult↗
PubMed1978

Differentiation of amylase isozyme in amniotic fluid with fetal age.

Composition of the amylase isozymes in the amniotic fluid and their transition with fetal age were studied by means of thin-layer acrylamide gel electrophoresis. The results indicate that amylase isozymes in the amniotic fluid were composed of a pancreatic type faint major isozyme and several salivary type isozymes consisting of an intense major and a few less intense minor bands. Characteristic changes in the pattern of these isozymes with fetal age consisted of a marked increase of the salivary type isozymes rather than of the pancreatic type isozyme. A densitometric analysis of the isozyme patterns proved that the ratio of the pancreatic type isozyme to the salivary type major isozyme was highly correlated with fetal age regardless of levels of amylase activity.

Amniotic Fluid↗