Activity and characterization of sialyltransferase from serum of normal rats, of rats bearing Zajdela ascitic hepatoma, in normal host liver and in Zajdela hepatoma cells.

Comparative studies on the content of sialic acid and on the sialyltransferase activity in normal serum and in serum of rats with Zajdela ascitic hepatoma in different phases of tumor development have been conducted. Unlike the serum from animals with tumors, in which the sialic acid quantity increases in dependence of the stage of tumor development, the activity of serum sialyltransferase statistically augmented only in serum of rats at the final stage of tumor progression. The sialyltransferase activity towards asialofetuin as an acceptor in normal liver and in Zajdela hepatoma cells, was measured and a decrease in this activity in tumor cells as well as in host liver was found.

Comparative studies on the uridine-5'-diphosphate-galactose: glycoprotein galactosyltransferase activity in rat liver and Zajdela ascitic hepatoma.

We report here data on the galactosyltransferase activity in serum, liver and Zajdela ascitic hempatoma cells and about the rate of galactose attachment to appropriate acceptors by beta(1-4, beta(1-3) and alpha(1-3) linkages in liver and hepatoma cell homogenates. It was established that in serum of Zajdela bearing rats, in host liver and in Zajdela ascitic cells, galactosyltransferase activity towards ovomucoid was elevated in comparison with control serum and liver. The activity towards low molecular acceptor (N-acetylglucosamine) in liver and hepatoma was nearly the same.

gamma-Glutamyltranspeptidase and dipeptidyl peptidase IV activity in the serum of normal and hepatoma-bearing chickens and in the plasma membranes from liver and hepatoma Mc-29.

Investigations on the activity of gamma-glutamyltranspeptidase (GGT) and dipeptidyl peptidase IV (DPP IV) in the serum of healthy chickens and those bearing hepatoma Mc-29, and in liver and hepatoma plasma membranes were carried out. There was no difference in the serum enzyme activities of control and tumor-bearing chickens but the activity of GGT was twice higher and that of DPP IV 20 times lower in hepatoma plasma membranes than in chicken liver plasma membranes. Using thin-layer analytical isoelectric focusing in agarose gels it was established that the pI range of GGT from host serum and hepatoma plasma membranes was shifted to more acidic values.

Pattern of sialoglycoproteins obtained by chromatofocusing of chicken liver and hepatoma Mc-29 microsomal preparations labelled in vivo with 3H-leucine and N-acetyl-14C-mannosamine.

Chromatofocusing has been used for separation of chicken liver and virus-induced hepatoma Mc-29 microsomal glycoproteins double labelled in vivo with 3H-leucine and N-acetyl-14C-mannosamine. The sialoglycoprotein profile was obtained by plotting the pH-values, as well as the values of the calculated specific activity (SA-cpm/mg protein) in each fraction, in the graphs. Different patterns for liver and hepatoma sialoglycoproteins were detected.

Partial characterization of microsomal sialyltransferase from chicken liver and hepatoma Mc-29: II. Measurement of enzyme activities utilizing microsomal glycoproteins as exogenous acceptors.

Microsomal sialyltransferase was assayed in chicken liver and hepatoma Mc-29 utilizing liver and hepatoma microsomal glycoprotein fractions, treated with Triton X-100, as exogenous acceptors. In a homologous assay system containing enzyme and acceptor from one and the same tissue no quantitative dependence of enzyme activity was revealed with increasing amount of the acceptor. In mixed experiments in which liver enzyme activity was tested towards hepatoma acceptor glycoproteins, a gradual drop in sialyltransferase activity occurred with increasing quantities of the acceptor.

Partial characterization of microsomal sialyltransferase from chicken liver and hepatoma Mc-29: I. Effect of nucleotides and metal ions.

CMP-N-acetylneuraminic acid: glycoprotein sialyltransferase activities were assayed in microsomal fractions from chicken liver and hepatoma, induced by the leukosis virus strain Mc-29, using asialofetuin as the substrate acceptor of N-acetylneuraminic acid. The effect of some nucleotides and metal ions on the enzyme activity was investigated. Kinetic studies revealed that the Km values toward asialofetuin at a saturation concentrations of CMP-N-acetylneuraminic acid for both liver and hepatoma enzymes are very closed, while V value was lower for the tumor enzyme.

A comparison of galactosyltransferase activity in mouse ascites lymphoma cells (Ly/Ya), in cultured lymphoma cells, in ascitic fluid and culture medium.

Comparative studies were carried out on the galactosyltransferase activity in ascites lymphoma cells isolated from mouse with ascitic lymphoma Ly/Ya, in these cells grown in vitro (24 hrs culture), in ascitic fluid and culture medium. The effect of varying amounts of UDP-galactose on transfer rate of galactose to ovomucoid by the cell enzyme (ascitic and cultured lymphoma cells) and by the soluble enzyme (ascitic fluid and culture medium) was studied. The activity of the enzyme in the cell culture medium was 2.

Effect of hydrocortisone on sialyltransferase activity in the rat small intestine during maturation. Changes along the villus-crypt axis and in fetal organ culture.

Sialyltransferase activity was assayed in rat intestinal cells isolated as fractions reflecting the villus-crypt axis of differentiation. In 13-day-old rats both endo- and exogenous sialyltransferase activity reached their maximum in undifferentiated crypt cells and their peaks overlapped. In contrast, sialyltransferase of the adult intestine was 4-fold lower than that of sucklings in the crypts, with slight tendency to be transferred to the villus cells.

Effect of fluororotic acid on the sialylation of the chicken liver, hepatoma MC-29 and serum glycoconjugates.

Fluororotic acid, an orotic acid analogue which interferes with the nucleotide and RNA biosynthesis, was tested to determine its effect on: a) 14C-glucosamine and 14C-N-acetylmannosamine incorporation into acid-soluble nucleotide-sugars and into b) glycoconjugates from chicken liver and hepatoma induced by the avian leukosis strain Mc-29. In vivo metabolism studies indicated that this agent alters the nucleotide biosynthesis in both tissues investigated and causes a decrease in the sialylation rate of liver, hepatoma and serum glycolipids and glycoproteins.

Isolation and characterization of chicken liver and hepatoma Mc-29 endoplasmic reticulum and Golgi apparatus membranes and biosynthesis of their glycoconjugates.

Rough and smooth endoplasmic reticulum (ER) membranes and trans-Golgi apparatus (GA) fraction, intermediate GA fraction, and cis-GA fraction from White Leghorn chicken liver and hepatoma Mc-29 were isolated. Their purity was checked by electron microscopy and by determination of the activity of the marker enzymes. Rough and smooth membranes were also identified by calculation of the ratio between the content of RNA and the total phospholipids.

Galactosyltransferase: multiple forms in serum of normal and hepatoma Mc-29 bearing chickens and from liver and hepatoma microsomal and plasma membrane preparations.

The multiple forms of galactosyltransferase in chicken serum and in microsomal and plasma membrane preparations from liver and viral induced hepatoma Mc-29 have been studied by isoelectric focussing. An elevation of the hepatoma plasma membrane enzyme activity was described and in the pattern of the multiple forms of the enzyme two forms were found (pI-5.34 and 8.

Characterization of sialyltransferases from serum of normal and hepatoma Mc-29 bearing chickens.

Sialyltransferase was measured in serum of normal and hepatoma Mc-29 bearing chickens. By preparative isoelectric focusing the multiple forms of sialyltransferase from both kind of serums was studied as well. By using influenza virus neuraminidase an attempt was made for partial structural characterization of the sialylation sites in asialofetuin applied as exogenous acceptor for sialyltransferase determination.

Studies on N-acetylneuraminic acid biosynthesis in chicken liver and hepatoma Mc-29 by using [14C]N-acetylmannosamine and [14C]glucosamine.

The biosynthesis of free N-acetylneuraminic (sialic) acid (N-acetylneuraminic + CMP-N-acetylneuraminic acid) in chicken liver and hepatoma Mc-29 by using [14C]N-acetylmannosamine and [14C]glucosamine was studied in vivo. The specific activity (SA) of hepatoma N-acetylneuraminic acid labelled with [14C]glucosamine is lower than that of liver, showing that the rate of conversion of UDP-N-acetylglucosamine to N-acetylneuraminic acid is reduced in tumor cells. The biosynthesis rate of sialic acid in hepatoma cells is higher when [14C]N-acetylmannosamine was applied.

Glycosidases in normal and regenerating chicken liver, hepatoma Mc-29, Rous sarcoma, in turkey poult liver and hemocytoblastomes, provoked by the leukosis virus strain Mc-31.

Four glycosidases (beta-galactosidase, alpha-mannosidase, alpha-fucosidase and beta-N-acetylglucosaminidase) were studied in chicken normal and regenerating liver, in turkey poult liver and in virus induced avian tumors--chicken hepatoma (strain Mc-29), Rous sarcoma (strain Schmidt-Ruppin) and turkey poult hemocytoblastoma nodules (strain Mc-31). The multiple forms of beta-N-acetylglucosaminidase were assayed as well. A particular enzyme pattern was found in the tumor lines under investigation.

Comparative study on fucosylation of chicken liver and virus-induced hepatoma Mc-29.

Comparative studies on fucoprotein metabolism of chicken liver and hepatoma Mc-29 have been carried out and the following parameters were determined: the incorporation rate of [14C]fucose into hepatoma and liver total tissue homogenate, acid-soluble and acid-insoluble fractions, acid-soluble nucleotide fraction and into plasma-membrane acid-precipitable fraction; the activity of microsomal and plasma-membrane fucosyltransferase; the electrophoretic pattern of hepatoma and liver plasma-membrane proteins and the incorporation of [14C]fucose into the glycoprotein fractions in both plasma-membrane preparations. It was found that the labelling of hepatoma tissue homogenate and plasma membranes was higher than that of the same liver preparations 3 hr after the [14C]fucose injection. This finding was supported by a considerably elevated hepatoma fucosyltransferase activity.

Multiple forms of chicken liver and hepatoma Mc-29 microsomal and plasma-membrane sialyl and fucosyltransferases.

Multiple forms of microsomal and plasma membrane sialyl and fucosyltransferases from chicken liver and transplantable hepatoma Mc-29 have been separated by means of isoelectric focusing. A net different pattern was distinguished between liver and hepatoma microsomal and plasma-membrane associated transferases. Microsomal sialyltransferase from hepatoma Mc-29 has typical forms with pI = 5.

Effect of silymarin (Carsil) on the microsomal glycoprotein and protein biosynthesis in liver of rats with experimental galactosamine hepatitis.

The effect of the hepatoprotective drug silymarin (Carsil) on the incorporation rate of 14C-leucine into total proteins and on the biosynthesis of UDP-N-acetylhexosamine and microsomal glycoproteins using 14C-glucose of rat liver with D-galactosamine hepatitis was studied. It was found that i.p.

Effect of D-glucosamine on the content and synthesis of UDP-sugars and plasma membrane associated carbohydrates in chicken liver and hepatoma Mc-29.

1. Comparative studies on the effect of D-glucosamine on the synthesis of UDP-sugars and on the incorporation rate of [14C]glucose into neutral sugars, sialic acid and glucosamine isolated from chicken liver and hepatoma Mc-29 plasma membranes have been carried out. 2.

Phospholipid composition of subcellular fractions and phospholipid-exchange activity in chicken liver and MC-29 hepatoma.

The phospholipid composition of mitochondria, microsomes and plasma membranes from liver and MC-29 hepatoma from White Leghorn chickens has been investigated. It was established that all mitochondria and microsome phospholipid fractions obtained from MC-29 hepatoma are increased strongly compared to those from liver. The sphingomyelin augmentation was particularly great.

Adenylate cyclase activity in plasma membranes of chicken liver and of Mc-29 virus induced hepatoma.

1. Adenylate cyclase activity in homogenate and plasma membrane preparations from chicken liver and from Mc-29 virus induced transplantable hepatoma has been investigated. The basal enzyme activity from both liver and hepatoma homogenates and plasma membranes was similar.

Hepatoprotective effect of silymarin (carsil) on liver of D-galactosamine treated rats. Biochemical and morphological investigations.

The hepatoprotective effect of carsil (generic name silymarin) on a model of liver intoxication with D-galactosamine in rats is studied. The changes in the activity of the serum enzymes GOT, GPT, MDH, SDH, ICDH, AP. AhE and the total protein as well as the UDP-sugars content in the liver is investigated.

Isolation and partial characterization of plasma membranes from chicken liver and from Mc-29 virus induced transplantable hepatoma.

Plasma membranes have been isolated from chicken liver and from Mc-29 virus induced transplantable hepatoma. The purity of membrane preparations has been checked by electron microscopy and by determination of the activity of some enzymes: 5'-nucleotidase, Na+, K+-ATP-ase, Mg2+-ATP-ase, alkaline beta-glycerophosphatase and glucose-6-phosphatase. In hepatoma membranes the activity of 5'-nucleotidase, Na+, K+-ATP-ase and Mg2+-ATP-ase was lower, that of alkaline phosphatase higher, than in liver membrane preparation.

Galactosamine is an inducer of Gal genes in Saccharomyces cerevisiae.

In yeast cells galactosamine in concentrations of 0.1 1M partially inhibits the synthesis of RNA but has little effect on the protein synthesis. In vivo and in vitro studies show that galactosamine is metabolized in yeast to UDP-N-acetylhexosamines but at a reduced rate, compared to the metabolism of galactose.