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Biomedical subjects

S Oshiro

Publications and source records attributed to S Oshiro.

6 recordsLinked to original sources
PubMed1992

Catabolism of hemoglobin-haptoglobin complex in microsome subfractions.

After internalization of hemoglobin-haptoglobin complex (Hb-Hp) via receptor-mediated endocytosis (RME) into liver parenchymal cells, organelles containing the complex distribute in the microsome fraction (Ms). Prior to the catabolism, Hb-Hp dissociates symmetrically into two 82,000-dalton (82 kDa) subunits. In the present investigation, the first event of Hb-Hp metabolism in Ms were further examined after [3H-heme, 14C-glogin]Hb-Ho or [125I-Hb]Hp injection to rats. Shortly after the internalization of Hb-Hp, this complex in Ms was intact. At 60 min after injection, radioactive materials of Ms extracted by freezing and thawing (F&T) with yield of 15% were composed of Hb-Hp, 82 kilodaltons (kDa) subunits and Hb metabolites with a ratio of 1:6:13. The heme metabolites were identified as [3H]bilirubin by high performance liquid chromatography (HPLC). The ratio of Hb-Hp/82 kDa subunits/Hb metabolites in microsome residue of the F&T was 40:8:1. The radioactivity in Ms at 60 min localized microsomes subfraction except Golgi light fraction. In electron microscope radioautography of microsome subfraction using [125I]Hb-Hp, silver grains were observed over or within morphologically heterogenous vesicles, e.g. vesicles containing very low density lipoprotein (VLDL) particles with appendage like multi-vesicular body (MVB) or compartment of uncoupling of receptor and ligand (CURL) in Goligi light and intermediate fractions. These studies suggest that Hb-Hp internalized by RME is dissociated symmetrically into two 82 kDa subunits in organelles of Ms, and that organelles with MVB or CURL-like structures are associated with Hb-Hp metabolism.

Animals↗
PubMed1979

Chemical modification of epsilon-amino groups in glutamine synthetase from Bacillus stearothermophilus with ethyl acetimidate.

The activity of glutamine synthetase [EC 6.3.2.1] from Bacillus stearothermophilus decreased slightly on modification with ethyl acetimidate. Acetamidination of 25--26 of the 2 epsilon-amino groups/subunit of the enzyme affected the maximum velocity, but not the Michaelis constant. The thermostability of the enzyme was considerably increased on acetamidination. Acetamidination of the enzyme did not affect the circular dichroism, the tryptophan fluorescence or the quenching effects of KI and acrylamide on the tryptophan emission. The fluorescence spectrum of p-toluidinylnaphthalene sulfonate bound to the enzyme changed on acetamidination.

Geobacillus stearothermophilus↗
PubMed1979

Cross-linking with diimidates of glutamine synthetase from Bacillus stearothermophilus.

Glutamine synthetase [EC 6.3.2.1] from Bacillus stearothermophilus was modified with diethyl malonimidate (DEM), dimethyl adipimidate (DMA), and dimethyl suberimidate (DMS). DMA modified most epsilon-amino groups. On modification with DMA, formation of 3 to 4 cross-links/subunit resulted in a large increase in thermostability. The activity, allosteric properties and fluorescence spectrum of the enzyme were not changed on cross-linking. The SDS-polyacrylamide gel electrophoretic profiles of DEM-, DMA-, and DMS-modified enzymes suggested that the interaction berween six subunits in each of the two hexagonal rings of the protein are heterologous and are different from those between the piled subunits on different rings.

Allosteric Regulation↗
PubMed1977

Potassium levels in the aqueous and vitreous humor after death.

It appears possible to utilize the potassium in the aqueous humor as well as the potassium in the vitreous humor for the estimation of the postmortem interval, especially if the factors relating to the body temperature are taken into consideration.

Animals↗