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Biomedical subjects

H Ohtake

Publications and source records attributed to H Ohtake.

At least 235 records · Page 13Linked to original sources
PubMed1979

Purification and characterization of zinc-binding protein from the liver of the partially hepatectomized rat.

Zn-binding protein in liver of the partially hepatectomized rat was purified by column chromatography on Sephadex G-75 and DEAE-cellulose. Homogeneity was judged by polyacrylamide-disc-gel electrophoresis. The molecular weight determined by gel-permeation chromatography in 6 M-guanidine hydrochloride was 6700. This value is in good agreement with the molecular weight calculated from the amino acid composition, which was 6073. Zn-binding protein was composed of 61 amino acid residues, and the distinctive features include an extremely high content of cysteine, which accounted for one-third of the total amino acid residues, and an absolute absence of aromatic amino acids as well as of histidine, leucine and arginine. The amino acid composition was similar to that of the metallothioneins previously isolated from rat liver and mouse liver. These observations suggest that the Zn-binding protein can be classified as a type of metallothionein. Zn-binding protein contained 8.2g-atoms of zinc per mol and traces of copper, but no cadmium. The molar ratio of thiol groups to zinc was calculated to be 2.5:1. Possible roles of this Zn-binding protein in the transport and storage of zinc in the liver are discussed.

Amino Acids↗
PubMed1978

Zinc-binding protein in the livers of neonatal, normal and partially hepatectomized rats.

In the livers of rats after partial hepatectomy the zinc concentration began to increase soon after the operation, reached a maximum value at 14h, and decreased to the original value by 25h after the operation. In contrast, the plasma zinc concentration continued to decrease during the first 10h after the operation and remained depressed for at least 28h. The plasma and hepatic zinc concentrations were relatively unaffected by sham-operation. Synchronous with the increase in the hepatic zinc concentration after the partial hepatectomy, there was an appearance of zinc-binding protein (Zn-binding protein) in the liver cytosol. Studies with small doses of actinomycin D and cycloheximide suggest that both RNA and protein syntheses are necessary for the induction of Zn-binding protein after partial hepatectomy. A high content of the Zn-binding protein was found in neonatal rat liver. The Zn-binding protein, however, was undetectable 40 days after birth. The Zn-binding protein was also found in the adult rat liver when stimulated to proliferate after the administration of isoprenaline followed by glucagon. These findings indicate a close linkage between the appearance of Zn-binding protein in the liver cytosol and the regulation of DNA synthesis.

Animals↗
PubMed1976

Respiratory behaviour of sea-urchin spermatozoa. I. Effect of pH and egg water on the respiratory rate.

Effects of pH and egg water on the respiration of sea-urchin spermatozoa were polarographically studied in three sea-urchins and one starfish species. Sea-urchin sperm respiration is extremely sensitive to change in the pH of the suspending medium over a wide range. In normal-sea water, the pH of the sperm suspension decreased from 8.02 to 7.62, after four to five minutes' incubation at 18 degrees C. The Respiratory Dilution Effect could be recognized in the same medium. However, when sea water was buffered with HEPES at pH 8.2, the Effect was no longer observed. The diffusate from egg water (jelly coat solution) brought about a striking increase in the respiration when added to moderately respiring spermatozoa in HEPES-sea water of pH values lower than 7.9. No inccrease in the respiration was observed when the diffusate was added to vigorously respiring spermatozoa in HEPES-sea water of pH values higher than 8.2. Sperm motility was also inhibited by acid pH, and this inhibition was reversed by the addition of the diffusate. It does not seem that there is any species-specificity among three sea-urchins and one starfish used. The role of the diffusate is discussed in relation to the penetration of spermatozoa through the jelly coat to the egg surface.

Animals↗
PubMed1976

Respiratory behaviour of sea-urchin spermatozoa. II. Sperm-activating substance obtained from jelly coat of sea-urchin eggs.

A sperm-activating substance (SAS) was obtained from the jelly coat of sea-urchin ova and its chemical properties were investigated in three sea-urchin species. The SAS was partially purified from the jelly coat of Pseudocentrotus eggs through several steps of purification by procedures consisting of charcoal adsorption, ion-exchange chromatography on DEAE-Sephadex A-25 column, and gel-filtration on Sephadex G-15 columns. The partially purified SAS was found to contain a ninhydrin-positive material and is inactivated by pronase digestion. The molecular weight of SAS was estimated as about 630 by gel-filtration through Sephadex G-25 and the isoelectric-point of SAS is located at about pH 5.3 by isoelectrofocusing method. The SAS is non-volatile, alcohol-soluble, and labile in a diluted alkaline or acid solution. The origin of SAS is discussed.

Animals↗