scholarly journals Sialyltransferase activity in regenerating rat liver

1977 ◽  
Vol 166 (3) ◽  
pp. 381-386 ◽  
Author(s):  
Franca Serafini-Cessi
Keyword(s):  
Sialic Acid ◽  
Partial Hepatectomy ◽  
Microsomal Fraction ◽  
Incubation Temperature ◽  
Submaxillary Gland ◽  
Sham Operation ◽  
Regenerating Liver ◽  
Microsomal Preparation ◽  
Sialyltransferase Activity ◽  
Triton X

Liver microsomal fractions catalyse the transfer of sialic acid from CMP-N-acetyl-neuraminic acid to various exogenous acceptors such as desialylated fetuin, desialylated human Tamm–Horsfall glycoprotein and desialylated bovine submaxillary-gland mucin. An increase in the rate of incorporation of sialic acid into desialylated glycoproteins was found after a lag period (7h) in regenerating liver. The increase was maximum 24h after partial hepatectomy for all acceptors tested. At later times after operation the sialyltransferase activity remained high only for desialylated fetuin. No soluble factors from liver or serum of partially hepatectomized animals influenced the activity of the sialyltransferases bound to the microsomal fraction. The sensitivity of sialyltransferases to activation by Triton X-100, added to the incubation medium, was unchanged in the microsomal preparation from animals 24h after sham operation or partial hepatectomy. The full activity of sialyltransferases towards the various desialylated acceptors showed some differences. Human Tamm–Horsfall glycoprotein was a good acceptor of sialic acid only when desialylated by mild acid hydrolysis. After this treatment, but not after enzymic hydrolysis, a decrease in molecular weight of human Tamm–Horsfall glycoprotein was observed. Further, the sialyltransferase activity as a function of incubation temperature gave different curves according to the acceptor used. The relationship between the biosynthesis of glycoproteins by regenerating liver and the sialyltransferase activity of microsomal fraction after partial hepatectomy is discussed.

STUDIES ON THE ENZYMIC FORMATION OF DI-IODOTYROSINE BY A MICROSOMAL PREPARATION OF GOAT SUBMAXILLARY GLAND

1969 ◽  
Vol 44 (2) ◽  
pp. 177-185 ◽  
Author(s):  
RATHA N. HATI ◽  
ASOKE G. DATTA
Keyword(s):  
Hydrogen Peroxide ◽  
Microsomal Fraction ◽  
Submaxillary Gland ◽  
Maximum Activity ◽  
Enzymic Activity ◽  
Subcellular Fractions ◽  
Ferric Ions ◽  
Microsomal Preparation

SUMMARY Subcellular fractions of goat submaxillary gland catalysed the iodination of monoiodotyrosine to form di-iodotyrosine; the microsomal fraction was found to have maximum activity. The enzyme needed copper or hydrogen peroxide for its activity. Thiourea and thiouracil inhibited the enzymic activity. Manganese and ferric ions inhibited the enzymic formation of di-iodotyrosine. The enzyme was solubilized by sodium desoxycholate treatment.

scholarly journals Phosphatidylethanolamine metabolism in rat liver after partial hepatectomy. Control of biosynthesis of phosphatidylethanolamine by the availability of ethanolamine

1992 ◽  
Vol 283 (1) ◽  
pp. 55-61 ◽  
Author(s):  
M Houweling ◽  
L B M Tijburg ◽  
W J Vaartjes ◽  
L M G van Golde
Keyword(s):  
Partial Hepatectomy ◽  
Rat Liver ◽  
Sham Operation ◽  
Regenerating Liver ◽  
Ethanolamine Kinase ◽  
Time Period

The effect of partial (70%) hepatectomy on phosphatidylethanolamine (PE) synthesis was studied in rat liver during the first 4 post-operative days. Between 4 and 96 h after partial hepatectomy, the mass of PE increased from 30% to 80% of sham-operation values. In line with the increase in PE mass, the rate of PE synthesis in vivo from [14C]ethanolamine was stimulated 1.6- and 1.3-fold at 22 and 48 h after partial hepatectomy respectively. Surprisingly, the activity of CTP:phosphoethanolamine cytidylyltransferase (EC 2.7.7.14) was virtually unchanged after partial hepatectomy. In addition, neither ethanolamine kinase (EC 2.7.1.82) nor ethanolaminephosphotransferase (EC 2.7.8.1) showed any changes in activity over the time period studied. Hepatic levels of ethanolamine and phosphoethanolamine were drastically increased after partial hepatectomy, as compared with sham operation, whereas levels of CDP-ethanolamine and microsomal diacylglycerol were not affected. Interestingly, partial hepatectomy caused the concentration of free ethanolamine in serum to increase from 29 microM to approx. 50 microM during the first day after surgery. In hepatocytes isolated from non-operated animals, incorporation of [3H]ethanolamine into PE was stimulated by increasing the ethanolamine concentration from 10 up to 50 microM, whereas the radioactivity associated with phosphoethanolamine only increased at ethanolamine concentrations higher than 30 microM. Taken together, our results indicate that the observed increase in serum ethanolamine concentration after partial hepatectomy is probably responsible for both the increase in PE biosynthesis and the accumulation of ethanolamine and phosphoethanolamine in regenerating liver.

scholarly journals Macro- and microtranscriptomic evidence of the monocyte recruitment to regenerating liver after partial hepatectomy in mouse model

2021 ◽  
Vol 138 ◽  
pp. 111516
Author(s):  
Andrey Elchaninov ◽  
Maria Nikitina ◽  
Polina Vishnyakova ◽  
Anastasia Lokhonina ◽  
Andrey Makarov ◽  
...  
Keyword(s):  
Mouse Model ◽  
Partial Hepatectomy ◽  
Regenerating Liver ◽  
Monocyte Recruitment

DEOXYCYTIDYLATE DEAMINASE LEVELS IN REGENERATING RAT LIVER

1961 ◽  
Vol 39 (6) ◽  
pp. 1043-1054 ◽  
Author(s):  
D. K. Myers ◽  
C. Anne Hemphill ◽  
Constance M. Townsend
Keyword(s):  
Dna Synthesis ◽  
Liver Regeneration ◽  
Partial Hepatectomy ◽  
Rat Liver ◽  
Deoxyribonucleic Acid ◽  
Regenerating Liver ◽  
Regenerating Rat Liver ◽  
High Level ◽  
Early Regeneration

Deoxycytidylate deaminase activity and net synthesis of deoxyribonucleic acid (DNA) in vivo were found to increase at approximately the same time during the early stages of liver regeneration. However, deaminase activity in the regenerating liver remained at a high level for 1 day after DNA synthesis had slowed down again during the later stages of regeneration. The increase in deaminase activity was restricted as a result of exposure to 600 r X radiation during early regeneration, but this effect only became evident 11–16 hours after the irradiation. Irradiation on the second day after partial hepatectomy, when deaminase levels in control regenerating livers were relatively constant, failed to affect the deaminase activity immediately but did produce a 40–50% decrease in activity 11–16 hours later. Other antimitotic agents, e.g., colchicine, had little effect on deaminase activity.

Effects of 2′-deoxy-5-fluorouridine on regenerating liver following partial hepatectomy in the rat

1988 ◽  
Vol 45 (2) ◽  
pp. 181-186 ◽  
Author(s):  
R.Mark Hoyle ◽  
Albert Banes ◽  
Stephen Bernard ◽  
Colin G. Thomas
Keyword(s):  
Partial Hepatectomy ◽  
Regenerating Liver

scholarly journals REUTILIZATION OF LYMPHOCYTE DNA BY CELLS OF INTESTINAL CRYPTS AND REGENERATING LIVER

1963 ◽  
Vol 18 (3) ◽  
pp. 515-523 ◽  
Author(s):  
B. J. Bryant
Keyword(s):  
Partial Hepatectomy ◽  
De Novo ◽  
Living Cells ◽  
Lymphoid Organs ◽  
Lymphoid Cells ◽  
Intestinal Cells ◽  
Regenerating Liver ◽  
Peyer's Patch ◽  
Intestinal Crypt ◽  
Recipient Liver

Lymphoid cells from mice injected 54 hours and 30 hours earlier with 3H-thymidine were washed and transfused into isogenic recipients at 29 to 30 hours after partial hepatectomy. The recipients were killed 28 to 30 hours later, and liver, intestine, Peyer's patch, spleen, and the transfused cells were examined in autoradiographs exposed 6 months. Approximately 80 per cent of the labeled transfused cells were classed as lymphocytes. The labeled DNA contained in the transfused cells was partitioned to about 14 times as many recipient liver and intestinal cells, appearing in 72 to 78 per cent of hepatocyte nuclei, in 30 to 35 per cent of liver reticuloendothelial nuclei, and in 90 to 95 per cent of intestinal crypt nuclei. The label was not comparably widespread in the lymphoid organs, but was limited to a few intensely labeled lymphocytes and a somewhat larger number of very weakly labeled cells. When heat-killed cells rather than living cells were transfused, intensely labeled lymphocytes were absent from the lymphoid organs, but the labeling of cells in the recipients was otherwise identical. The results suggest that (a) reutilized DNA is derived from dead cells, (b) reutilized DNA is mainly degraded to nucleosides and nucleotides, the usual immediate de novo DNA precursors, before reincorporation into DNA, and (c) DNA reutilization may occur in the lymphoid organs, but on a less active scale than in intestine or regenerating liver.

Purification par séparation de phase et caractérisation du plasmalemme de l'épicotyle de pois

1986 ◽  
Vol 64 (5) ◽  
pp. 448-455 ◽  
Author(s):  
Jacques Rembur ◽  
Pierre Landré ◽  
Arlette Nougarède
Keyword(s):  
Atpase Activity ◽  
Plasma Membranes ◽  
Microsomal Fraction ◽  
Alkaline Ph ◽  
Phase Partition ◽  
Pea Epicotyl ◽  
Glucan Synthetase ◽  
Triton X ◽  
Two Sides ◽  
Slight Contamination

The validity of phase partition to obtain a substantial proportion of vesicles of plasmalemma origin from the microsomal fraction of pea epicotyl has been demonstrated. In the fractions enriched with plasma membranes, N-naphthyl phtalamic acid binding and β-glucan synthetase II activity, showed a yield of about 60% and an enrichment of 2.3 and 2.2, respectively, in comparison with the microsomal fraction. When such plasmalemmic vesicles are permabilized by Triton X-100, an intense Mg2+-ATPase activity is obtained in presence of K+ at acid as well as alkaline pH. Inhibition of Mg2+-ATPase by vanadate in presence of K+ and its variations in relation to pH were shown. Dicyclohexylcarbodiimide and diethylstilbestrol inhibit 40–55% of this enzymatic activity, both at acid and neutral pH. The data show a slight contamination of the plasmalemmic fraction by endomembranes and suggest an asymmetry of the two sides of the plasmalemma.

scholarly journals Increased activity of a specific sialyltransferase in chronic myelogenous leukemia

Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1068-1071 ◽  
Author(s):  
MA Baker ◽  
RN Taub ◽  
A Kanani ◽  
I Brockhausen ◽  
A Hindenburg
Keyword(s):  
Enzyme Activity ◽  
Sialic Acid ◽  
Chronic Myelogenous Leukemia ◽  
Lectin Binding ◽  
Myelogenous Leukemia ◽  
Membrane Properties ◽  
Enzyme Specificity ◽  
Membrane Glycoproteins ◽  
Sialyltransferase Activity ◽  
Acceptor Group

Granulocytes from patients with chronic myelogenous leukemia (CML) are morphologically identical to their normal counterparts but show marked differences in circulation patterns and in some membrane properties. We have previously shown that there is abnormal lectin binding to CML granulocytes, and aberrant sialylation of membrane glycoproteins. To examine the changes in sialylation of CML granulocytes further, we have studied membrane preparations from CML and normal granulocytes for specific sialyltransferase activity. Because sialyltransferase enzymes are specific for the configuration of the acceptor group, enzyme activity was assayed by measuring transfer of sialic acid from CMP-14C- sialic acid to substrates of defined structure. As compared with those of normal counterparts, CML extracts catalyzed a 50% higher overall rate of sialylation of asialofetuin, a substrate possessing both N- and O-linked acceptors. Studies of enzyme specificity utilizing porcine and ovine submaxillary mucins, antifreeze glycoprotein and alpha-1 acid glycoprotein as acceptors showed that the increased sialylation by CML extracts was due primarily to substrates with the O-linked Gal beta 1--- -3GaINAc acceptor group. These data suggest that sialyltransferase activity is increased in CML granulocytes compared to normal granulocytes and that the increased enzyme activity is specific for O- linked Gal beta 1----3GaINAc. This enzyme activity may be directly responsible for the abnormal membrane sialylation and pathophysiological behavior of these cells.

scholarly journals 3-Hydroxy-3-methylglutaryl-coenzyme A reductase. A comparison of the modulation in vitro by phosphorylation and dephosphorylation to modulation of enzyme activity by feeding cholesterol- or cholestyramine-supplemented diets

1980 ◽  
Vol 185 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Konstantinos A. Mitropoulos ◽  
Brian L. Knight ◽  
Bernard E. A. Reeves
Keyword(s):  
Microsomal Fraction ◽  
Coenzyme A ◽  
Maximal Activity ◽  
Kinetic Properties ◽  
Standard Diet ◽  
Microsomal Preparation ◽  
Phosphoprotein Phosphatase ◽  
Coa Reductase ◽  
Hydroxymethylglutaryl Coa Reductase ◽  
Coenzyme A Reductase

The activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (hydroxymethylglutaryl-CoA reductase) was considerably inhibited during incubation with ATP+Mg2+. The inactivated enzyme was reactivated on further incubation with partially purified cytosolic phosphoprotein phosphatase. The inactivation was associated with a decrease in the apparent Km of the reductase for hydroxymethylglutaryl-CoA, and this was reversed on reactivation. The slight increase in activity observed during incubation of microsomal fraction without ATP was not associated with a change in apparent Km and, unlike the effect of the phosphatase, was not inhibited by NaF. Liver microsomal fraction from rats given cholesterol exhibited a low activity of hydroxymethylglutaryl-CoA reductase with a low apparent Km for hydroxymethylglutaryl-CoA. Mícrosomal fraction from rats fed cholestyramine exhibited a high activity with a high Km. To discover whether these changes had resulted from phosphorylation and dephosphorylation of the reductase, microsomal fraction from rats fed the supplemented diets and the standard diet were inactivated with ATP and reactivated with phosphoprotein phosphatase. Inactivation reduced the maximal activity of the reductase in each microsomal preparation and also reduced the apparent Km for hydroxymethylglutaryl-CoA. There was no difference between the preparations in the degree of inactivation produced by ATP. Treatment with phosphatase restored both the maximal activity and the apparent Km of each preparation, but never significantly increased the activity above that observed with untreated microsomal fraction. It is concluded that hydroxymethylglutaryl-CoA reductase in microsomal fraction prepared by standard procedures is almost entirely in the dephosphorylated form, and that the difference in kinetic properties in untreated microsomal fraction from rats fed the three diets cannot be explained by differences in the degree of phosphorylation of the enzyme.

Cholinephosphotransferase activities in microsomes and neuronal nuclei isolated from immature rabbit cerebral cortex: the use of endogenously generated diacylglycerols as substrate

1982 ◽  
Vol 60 (7) ◽  
pp. 724-733 ◽  
Author(s):  
R. Roy Baker ◽  
Huu-Yi Chang
Keyword(s):  
Phospholipase C ◽  
Microsomal Fraction ◽  
Neuronal Development ◽  
Nuclear Fraction ◽  
Neuronal Nuclei ◽  
Nuclear Membranes ◽  
Choline Phosphotransferase ◽  
Rabbit Cerebral Cortex ◽  
Low Levels ◽  
Triton X

A neuronal nuclear fraction (N1) and a microsomal fraction (P3) were isolated from homogenates of cerebral cortices of 15-day-old rabbits. A nuclear envelope fraction (E) was prepared from N1. To assay cholinephosphotransferase, diacylglycerols were first generated in the membranes of these subfractions using a phospholipase C (Bacillus cereus) preincubation. With levels of endogenous diacylglycerols producing maximal specific cholinephosphotransferase activities, an activity ratio of 1:1:5 was found for N1, P3, and E, respectively. An independent neuronal nuclear cholinephosphotransferase, concentrated in nuclear membranes, is indicated. With regard to changes in pH and concentrations of MgCl2 and CDP-choline, N1 and P3 activities responded in a similar manner. However, in contrast to P3, N1 activities were much more profoundly inhibited at low levels of Triton X-100 (0.01–0.02 w/v%) and N1 showed quite significant levels of cholinephosphotransferase activity in the absence of a phospholipase C preincubation. Choline phosphotransferase in N1 and P3 showed Km values for CDP-choline (0.028 and 0.031 mM, respectively) which were much lower than corresponding literature values determined using exogenous diacylglycerols as substrates for this enzyme. The presence of cholinephosphotransferase in neuronal nuclear membranes reflects a rather exceptional nuclear autonomy. This may be related to a need to maintain nuclear phospholipid in the absence of a well-developed endoplasmic reticulum at early stages of neuronal development or to synthesize phospholipid in response to functions unique to the nucleus.

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