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Biomedical subjects

S Fleischer

Publications and source records attributed to S Fleischer.

At least 271 records · Page 15Linked to original sources

Beta-hydroxybutyrate dehydrogenase: lack in ruminant liver mitochondria.

The enizyme D(-)-beta-hydroxybutyrate dehydrogenase has been reported to occur in all mitochondria isolated from mammalian tissues and is especially high in liver. By contrast only very low concentration of the enzyme is detectable in mitachondria from bovine and sheep liver. The amount of the enzyme in mitochondria from other ruminant tissues such as kidney and heart are comparable with those from mammalian sources. The verv low activity of beta-hydroxybutyrate dehydrogenase is not referable to the iniability of substrates to penetrate milochondria or to decreased electron transfer activity but rather to a lack of the enzyne in ruminant liver mitochondria.

Animals↗

Isolation and characterization of Golgi membranes from bovine liver.

Zonal centrifugation has been used to isolate a fraction from bovine liver which appears to be derived from the Golgi apparatus. Morphologically, the fraction consists mainly of sacs and tubular elements. Spherical inclusions, probably lipoproteins, are occasionally seen in negative stains of this material. The preparation is biochemically unique. UDP-galactose:N-acetyl glucosamine, galactosyl transferase activity is concentrated about 40-fold in this fraction compared to the homogenate. Rotenone- or antimycin-insensitive DPNH- or TPNH- cytochrome c reductase activities are 60-80% of the level of activities found in microsomes. Purified organelles from bovine liver such as plasma membranes, rough microsomes, mitochondria and nuclei have negligible levels of galactosyl transferase. Some activity is present in smooth microsomes but at a level compatible with the possible presence of Golgi membranes in this fraction. The Golgi fraction does not contain appreciable amounts of enzymes such as ATPase, 5'-nucleotidase, glycosidase, glucose-6-phosphatase, acid phosphatase, or succinate-cytochrome c reductase. Similar fractions isolated from bovine epididymis also have very high levels of galactosyl transferase. The fraction is heavily osmicated when incubated for long periods of time at elevated temperatures, a characteristic property of Golgi membranes.

Acid Phosphatase↗